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* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-07 14:33 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-07 14:33 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:6ece6fd6462be2477b1b0b5ee118db08fe78d5bd
commit 6ece6fd6462be2477b1b0b5ee118db08fe78d5bd
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 14:42 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 14:42 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:c8cdf710b589b2a23b6d8dcc25f23b8d74aff671
commit c8cdf710b589b2a23b6d8dcc25f23b8d74aff671
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 14:35 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 14:35 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:4bb80578ed9ffdb14f7405cf8f643817d9258e7d
commit 4bb80578ed9ffdb14f7405cf8f643817d9258e7d
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 14:34 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 14:34 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:8db6f222307dca684c30fae027ac65f039d9587e
commit 8db6f222307dca684c30fae027ac65f039d9587e
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 12:06 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 12:06 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:5702742889876f7dd18f2d9efd86c0961ce123b9
commit 5702742889876f7dd18f2d9efd86c0961ce123b9
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 11:38 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 11:38 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:d3c07a89f6f721343c88e18e824d4a5ac7db8e0b
commit d3c07a89f6f721343c88e18e824d4a5ac7db8e0b
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-08 10:21 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-08 10:21 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:9a25258baa2aae4ca9fce392f5f844d037599677
commit 9a25258baa2aae4ca9fce392f5f844d037599677
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-07 14:19 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-07 14:19 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:5568a418bd961188131c83f3f8292c0b022cdfe8
commit 5568a418bd961188131c83f3f8292c0b022cdfe8
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-07 14:06 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-07 14:06 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:738d52c4fc89414dc1d2143710cf924d4bdab88d
commit 738d52c4fc89414dc1d2143710cf924d4bdab88d
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-07 13:01 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-07 13:01 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a9c5d5aa92d3d081b8ebf0e913f699e8b59597d0
commit a9c5d5aa92d3d081b8ebf0e913f699e8b59597d0
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
* [gcc(refs/users/marxin/heads/sphinx-final)] sphinx: add tm.rst.in
@ 2022-11-07 12:38 Martin Liska
0 siblings, 0 replies; 11+ messages in thread
From: Martin Liska @ 2022-11-07 12:38 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:e6ad9959871bb7633d738879dc27e24684fd2fa8
commit e6ad9959871bb7633d738879dc27e24684fd2fa8
Author: Martin Liska <mliska@suse.cz>
Date: Mon Nov 7 13:21:38 2022 +0100
sphinx: add tm.rst.in
gcc/ChangeLog:
* doc/gccint/target-macros/tm.rst.in: New file.
Diff:
---
gcc/doc/gccint/target-macros/tm.rst.in | 6903 ++++++++++++++++++++++++++++++++
1 file changed, 6903 insertions(+)
diff --git a/gcc/doc/gccint/target-macros/tm.rst.in b/gcc/doc/gccint/target-macros/tm.rst.in
new file mode 100644
index 00000000000..17fc9e1b0aa
--- /dev/null
+++ b/gcc/doc/gccint/target-macros/tm.rst.in
@@ -0,0 +1,6903 @@
+[TARGET_ASM_OPEN_PAREN]
+.. c:var:: const char * TARGET_ASM_OPEN_PAREN
+
+ These target hooks are C string constants, describing the syntax in the
+ assembler for grouping arithmetic expressions. If not overridden, they
+ default to normal parentheses, which is correct for most assemblers.
+
+[TARGET_ASM_OPEN_PAREN]
+
+[TARGET_ASM_BYTE_OP]
+.. c:var:: const char * TARGET_ASM_BYTE_OP
+
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
+ byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ ``NULL``, indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+[TARGET_ASM_BYTE_OP]
+
+[TARGET_ASM_INTEGER]
+.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
+
+ The ``assemble_integer`` function uses this hook to output an
+ integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
+ in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
+ function should return ``true`` if it was able to output the
+ object. If it returns false, ``assemble_integer`` will try to
+ split the object into smaller parts.
+
+ The default implementation of this hook will use the
+ ``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
+ when the relevant string is ``NULL``.
+
+[TARGET_ASM_INTEGER]
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
+
+ This target hook is used to emit assembly strings required by the target
+ after the .cfi_startproc directive. The first argument is the file stream to
+ write the strings to and the second argument is the function's declaration. The
+ expected use is to add more .cfi_\* directives.
+
+ The default is to not output any assembly strings.
+
+[TARGET_ASM_POST_CFI_STARTPROC]
+
+[TARGET_ASM_DECL_END]
+.. function:: void TARGET_ASM_DECL_END (void)
+
+ Define this hook if the target assembler requires a special marker to
+ terminate an initialized variable declaration.
+
+[TARGET_ASM_DECL_END]
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the label :samp:`{name}` global;
+ that is, available for reference from other files.
+
+ The default implementation relies on a proper definition of
+ ``GLOBAL_ASM_OP``.
+
+[TARGET_ASM_GLOBALIZE_LABEL]
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
+ global; that is, available for reference from other files.
+
+ The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
+
+[TARGET_ASM_GLOBALIZE_DECL_NAME]
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
+
+ This target hook is a function to output to the stdio stream
+ :samp:`{stream}` some commands that will declare the name associated with
+ :samp:`{decl}` which is not defined in the current translation unit. Most
+ assemblers do not require anything to be output in this case.
+
+[TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
+
+ This target hook emits a label at the beginning of each FDE. It
+ should be defined on targets where FDEs need special labels, and it
+ should write the appropriate label, for the FDE associated with the
+ function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
+ The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
+ exception table. The fourth argument, :samp:`{empty}`, is a boolean:
+ true if this is a placeholder label for an omitted FDE.
+
+ The default is that FDEs are not given nonlocal labels.
+
+[TARGET_ASM_EMIT_UNWIND_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
+
+ This target hook emits a label at the beginning of the exception table.
+ It should be defined on targets where it is desirable for the table
+ to be broken up according to function.
+
+ The default is that no label is emitted.
+
+[TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
+
+ If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
+ used to emit a directive to install a personality hook into the unwind
+ info. This hook should not be used if dwarf2 unwind info is used.
+
+[TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
+
+ If necessary, modify personality and LSDA references to handle indirection.
+ The original symbol is in ``origsymbol`` and if ``pubvis`` is true
+ the symbol is visible outside the TU.
+
+[TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
+
+[TARGET_ASM_UNWIND_EMIT]
+.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
+
+ This target hook emits assembly directives required to unwind the
+ given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
+ returns ``UI_TARGET``.
+
+[TARGET_ASM_UNWIND_EMIT]
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
+
+ True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
+ the assembly for :samp:`{insn}` has been emitted, false if the hook should
+ be called afterward.
+
+[TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
+
+ For DWARF-based unwind frames, two CFI instructions provide for save and
+ restore of register state. GCC maintains the current frame address (CFA)
+ separately from the register bank but the unwinder in libgcc preserves this
+ state along with the registers (and this is expected by the code that writes
+ the unwind frames). This hook allows the target to specify that the CFA data
+ is not saved/restored along with the registers by the target unwinder so that
+ suitable additional instructions should be emitted to restore it.
+
+[TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
+
+[TARGET_ASM_INTERNAL_LABEL]
+.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
+
+ A function to output to the stdio stream :samp:`{stream}` a label whose
+ name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
+
+ It is absolutely essential that these labels be distinct from the labels
+ used for user-level functions and variables. Otherwise, certain programs
+ will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table of the
+ object file. Most assemblers have a naming convention for labels that
+ should be excluded; on many systems, the letter :samp:`L` at the
+ beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
+
+[TARGET_ASM_INTERNAL_LABEL]
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
+
+ A target hook to output to the stdio stream :samp:`{file}` any text necessary
+ for declaring the name :samp:`{name}` of a constant which is being defined. This
+ target hook is responsible for outputting the label definition (perhaps using
+ ``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
+ and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
+ will be an internal label.
+
+ The default version of this target hook, define the :samp:`{name}` in the
+ usual manner as a label (by means of ``assemble_label``).
+
+ You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
+
+[TARGET_ASM_DECLARE_CONSTANT_NAME]
+
+[TARGET_ASM_TTYPE]
+.. function:: bool TARGET_ASM_TTYPE (rtx sym)
+
+ This hook is used to output a reference from a frame unwinding table to
+ the type_info object identified by :samp:`{sym}`. It should return ``true``
+ if the reference was output. Returning ``false`` will cause the
+ reference to be output using the normal Dwarf2 routines.
+
+[TARGET_ASM_TTYPE]
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` some
+ commands that will make the symbol(s) associated with :samp:`{decl}` have
+ hidden, protected or internal visibility as specified by :samp:`{visibility}`.
+
+[TARGET_ASM_ASSEMBLE_VISIBILITY]
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
+
+ Generate a patchable area at the function start, consisting of
+ :samp:`{patch_area_size}` NOP instructions. If the target supports named
+ sections and if :samp:`{record_p}` is true, insert a pointer to the current
+ location in the table of patchable functions. The default implementation
+ of the hook places the table of pointers in the special section named
+ ``__patchable_function_entries``.
+
+[TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for entry to a
+ function. The prologue is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving registers that must be
+ saved, and allocating :samp:`{size}` additional bytes of storage for the
+ local variables. :samp:`{file}` is a stdio stream to which the assembler
+ code should be output.
+
+ The label for the beginning of the function need not be output by this
+ macro. That has already been done when the macro is run.
+
+ .. index:: regs_ever_live
+
+ To determine which registers to save, the macro can refer to the array
+ ``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
+ :samp:`{r}` is used anywhere within the function. This implies the function
+ prologue should save register :samp:`{r}`, provided it is not one of the
+ call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
+ ``regs_ever_live``.)
+
+ On machines that have 'register windows', the function entry code does
+ not save on the stack the registers that are in the windows, even if
+ they are supposed to be preserved by function calls; instead it takes
+ appropriate steps to 'push' the register stack, if any non-call-used
+ registers are used in the function.
+
+ .. index:: frame_pointer_needed
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether a
+ frame pointer is in wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. See :ref:`elimination`.
+
+ The function entry code is responsible for allocating any stack space
+ required for the function. This stack space consists of the regions
+ listed below. In most cases, these regions are allocated in the
+ order listed, with the last listed region closest to the top of the
+ stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
+ the highest address if it is not defined). You can use a different order
+ for a machine if doing so is more convenient or required for
+ compatibility reasons. Except in cases where required by standard
+ or by a debugger, there is no reason why the stack layout used by GCC
+ need agree with that used by other compilers for a machine.
+
+[TARGET_ASM_FUNCTION_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`prologue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_END_PROLOGUE]
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs assembler code at the start of an
+ epilogue. This should be used when the function epilogue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. See :ref:`epilogue-instruction-pattern`.
+
+[TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
+
+ If defined, a function that outputs the assembler code for exit from a
+ function. The epilogue is responsible for restoring the saved
+ registers and stack pointer to their values when the function was
+ called, and returning control to the caller. This macro takes the
+ same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
+ registers to restore are determined from ``regs_ever_live`` and
+ ``CALL_USED_REGISTERS`` in the same way.
+
+ On some machines, there is a single instruction that does all the work
+ of returning from the function. On these machines, give that
+ instruction the name :samp:`return` and do not define the macro
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
+
+ Do not define a pattern named :samp:`return` if you want the
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
+ switches to control whether return instructions or epilogues are used,
+ define a :samp:`return` pattern with a validity condition that tests the
+ target switches appropriately. If the :samp:`return` pattern's validity
+ condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for these
+ two cases is completely different. To determine whether a frame pointer
+ is wanted, the macro can refer to the variable
+ ``frame_pointer_needed``. The variable's value will be 1 when compiling
+ a function that needs a frame pointer.
+
+ Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
+ ``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
+ The C variable ``current_function_is_leaf`` is nonzero for such a
+ function. See :ref:`leaf-functions`.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020 when
+ given :option:`-mrtd` pops arguments in functions that take a fixed
+ number of arguments.
+
+ .. index:: pops_args, crtl->args.pops_args
+
+ Your definition of the macro ``RETURN_POPS_ARGS`` decides which
+ functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
+ needs to know what was decided. The number of bytes of the current
+ function's arguments that this function should pop is available in
+ ``crtl->args.pops_args``. See :ref:`scalar-return`.
+
+[TARGET_ASM_FUNCTION_EPILOGUE]
+
+[TARGET_ASM_INIT_SECTIONS]
+.. function:: void TARGET_ASM_INIT_SECTIONS (void)
+
+ Define this hook if you need to do something special to set up the
+ :samp:`varasm.cc` sections, or if your target has some special sections
+ of its own that you need to create.
+
+ GCC calls this hook after processing the command line, but before writing
+ any assembly code, and before calling any of the section-returning hooks
+ described below.
+
+[TARGET_ASM_INIT_SECTIONS]
+
+[TARGET_ASM_NAMED_SECTION]
+.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
+
+ Output assembly directives to switch to section :samp:`{name}`. The section
+ should have attributes as specified by :samp:`{flags}`, which is a bit mask
+ of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
+ is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
+ this section is associated.
+
+[TARGET_ASM_NAMED_SECTION]
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
+
+ This hook can be used to encode ELF section flags for which no letter
+ code has been defined in the assembler. It is called by
+ ``default_asm_named_section`` whenever the section flags need to be
+ emitted in the assembler output. If the hook returns true, then the
+ numerical value for ELF section flags should be calculated from
+ :samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
+ normal sequence of letter codes. If the hook is not defined, or if it
+ returns false, then :samp:`{num}` is ignored and the traditional letter sequence
+ is emitted.
+
+[TARGET_ASM_ELF_FLAGS_NUMERIC]
+
+[TARGET_ASM_FUNCTION_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
+
+ Return preferred text (sub)section for function :samp:`{decl}`.
+ Main purpose of this function is to separate cold, normal and hot
+ functions. :samp:`{startup}` is true when function is known to be used only
+ at startup (from static constructors or it is ``main()``).
+ :samp:`{exit}` is true when function is known to be used only at exit
+ (from static destructors).
+ Return NULL if function should go to default text section.
+
+[TARGET_ASM_FUNCTION_SECTION]
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
+
+ Used by the target to emit any assembler directives or additional
+ labels needed when a function is partitioned between different
+ sections. Output should be written to :samp:`{file}`. The function
+ decl is available as :samp:`{decl}` and the new section is 'cold' if
+ :samp:`{new_is_cold}` is ``true``.
+
+[TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
+
+[TARGET_ASM_RELOC_RW_MASK]
+.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
+
+ Return a mask describing how relocations should be treated when
+ selecting sections. Bit 1 should be set if global relocations
+ should be placed in a read-write section; bit 0 should be set if
+ local relocations should be placed in a read-write section.
+
+ The default version of this function returns 3 when :option:`-fpic`
+ is in effect, and 0 otherwise. The hook is typically redefined
+ when the target cannot support (some kinds of) dynamic relocations
+ in read-only sections even in executables.
+
+[TARGET_ASM_RELOC_RW_MASK]
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
+
+ Return true to generate ADDR_DIF_VEC table
+ or false to generate ADDR_VEC table for jumps in case of -fPIC.
+
+ The default version of this function returns true if flag_pic
+ equals true and false otherwise
+
+[TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
+
+[TARGET_ASM_SELECT_SECTION]
+.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
+
+ Return the section into which :samp:`{exp}` should be placed. You can
+ assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
+ some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
+ requires link-time relocations. Bit 0 is set when variable contains
+ local relocations only, while bit 1 is set for global relocations.
+ :samp:`{align}` is the constant alignment in bits.
+
+ The default version of this function takes care of putting read-only
+ variables in ``readonly_data_section``.
+
+ See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
+
+[TARGET_ASM_SELECT_SECTION]
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
+
+ Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
+ should be placed. You can assume that :samp:`{x}` is some kind of
+ constant in RTL. The argument :samp:`{mode}` is redundant except in the
+ case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
+ in bits.
+
+ The default version of this function takes care of putting symbolic
+ constants in ``flag_pic`` mode in ``data_section`` and everything
+ else in ``readonly_data_section``.
+
+[TARGET_ASM_SELECT_RTX_SECTION]
+
+[TARGET_ASM_UNIQUE_SECTION]
+.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
+
+ Build up a unique section name, expressed as a ``STRING_CST`` node,
+ and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
+ As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
+ the initial value of :samp:`{exp}` requires link-time relocations.
+
+ The default version of this function appends the symbol name to the
+ ELF section name that would normally be used for the symbol. For
+ example, the function ``foo`` would be placed in ``.text.foo``.
+ Whatever the actual target object format, this is often good enough.
+
+[TARGET_ASM_UNIQUE_SECTION]
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
+
+ Return the readonly data or reloc readonly data section associated with
+ :samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
+ over the former.
+ The default version of this function selects ``.gnu.linkonce.r.name`` if
+ the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
+ or ``.data.rel.ro.name`` if function is in ``.text.name``, and
+ the normal readonly-data or reloc readonly data section otherwise.
+
+[TARGET_ASM_FUNCTION_RODATA_SECTION]
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
+
+ Usually, the compiler uses the prefix ``".rodata"`` to construct
+ section names for mergeable constant data. Define this macro to override
+ the string if a different section name should be used.
+
+[TARGET_ASM_MERGEABLE_RODATA_PREFIX]
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
+
+ Return the section that should be used for transactional memory clone
+ tables.
+
+[TARGET_ASM_TM_CLONE_TABLE_SECTION]
+
+[TARGET_ASM_CONSTRUCTOR]
+.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
+
+ If defined, a function that outputs assembler code to arrange to call
+ the function referenced by :samp:`{symbol}` at initialization time.
+
+ Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
+ no arguments and with no return value. If the target supports initialization
+ priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
+ otherwise it must be ``DEFAULT_INIT_PRIORITY``.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2) the
+ target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
+ is not defined.
+
+[TARGET_ASM_CONSTRUCTOR]
+
+[TARGET_ASM_DESTRUCTOR]
+.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
+
+ This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
+ functions rather than initialization functions.
+
+[TARGET_ASM_DESTRUCTOR]
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
+
+ A function that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with multiple
+ inheritance. The thunk acts as a wrapper around a virtual function,
+ adjusting the implicit object parameter before handing control off to
+ the real function.
+
+ First, emit code to add the integer :samp:`{delta}` to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the ``this`` pointer
+ in C++. This is the incoming argument *before* the function prologue,
+ e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
+ all other incoming arguments.
+
+ Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
+ made after adding ``delta``. In particular, if :samp:`{p}` is the
+ adjusted pointer, the following adjustment should be made:
+
+ .. code-block:: c++
+
+ p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
+
+ After the additions, emit code to jump to :samp:`{function}`, which is a
+ ``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from :samp:`{FUNCTION}` will
+ return to whoever called the current :samp:`thunk`.
+
+ The effect must be as if :samp:`{function}` had been called directly with
+ the adjusted first argument. This macro is responsible for emitting all
+ of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
+ and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
+
+ The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
+ have already been extracted from it.) It might possibly be useful on
+ some targets, but probably not.
+
+ If you do not define this macro, the target-independent code in the C++
+ front end will generate a less efficient heavyweight thunk that calls
+ :samp:`{function}` instead of jumping to it. The generic approach does
+ not support varargs.
+
+[TARGET_ASM_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
+
+ A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
+ to output the assembler code for the thunk function specified by the
+ arguments it is passed, and false otherwise. In the latter case, the
+ generic approach will be used by the C++ front end, with the limitations
+ previously exposed.
+
+[TARGET_ASM_CAN_OUTPUT_MI_THUNK]
+
+[TARGET_ASM_FILE_START]
+.. function:: void TARGET_ASM_FILE_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects to
+ find at the beginning of a file. The default behavior is controlled
+ by two flags, documented below. Unless your target's assembler is
+ quite unusual, if you override the default, you should call
+ ``default_file_start`` at some point in your target hook. This
+ lets other target files rely on these variables.
+
+[TARGET_ASM_FILE_START]
+
+[TARGET_ASM_FILE_END]
+.. function:: void TARGET_ASM_FILE_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of a file. The default is to output nothing.
+
+[TARGET_ASM_FILE_END]
+
+[TARGET_ASM_LTO_START]
+.. function:: void TARGET_ASM_LTO_START (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the start of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_START]
+
+[TARGET_ASM_LTO_END]
+.. function:: void TARGET_ASM_LTO_END (void)
+
+ Output to ``asm_out_file`` any text which the assembler expects
+ to find at the end of an LTO section. The default is to output
+ nothing.
+
+[TARGET_ASM_LTO_END]
+
+[TARGET_ASM_CODE_END]
+.. function:: void TARGET_ASM_CODE_END (void)
+
+ Output to ``asm_out_file`` any text which is needed before emitting
+ unwind info and debug info at the end of a file. Some targets emit
+ here PIC setup thunks that cannot be emitted at the end of file,
+ because they couldn't have unwind info then. The default is to output
+ nothing.
+
+[TARGET_ASM_CODE_END]
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ pseudo-op to declare a library function name external. The name of the
+ library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
+
+[TARGET_ASM_EXTERNAL_LIBCALL]
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
+
+ This target hook is a function to output to :samp:`{asm_out_file}` an assembler
+ directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
+ .no_dead_code_strip directive.
+
+[TARGET_ASM_MARK_DECL_PRESERVED]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
+
+ Provides the target with the ability to record the gcc command line
+ switches provided as argument.
+
+ By default this hook is set to NULL, but an example implementation is
+ provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
+ it records the switches as ASCII text inside a new, string mergeable
+ section in the assembler output file. The name of the new section is
+ provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES]
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
+
+ This is the name of the section that will be created by the example
+ ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
+ hook.
+
+[TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
+
+ Write the assembly code to define section anchor :samp:`{x}`, which is a
+ ``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
+ The hook is called with the assembly output position set to the beginning
+ of ``SYMBOL_REF_BLOCK (x)``.
+
+ If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
+ it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
+ If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
+ is ``NULL``, which disables the use of section anchors altogether.
+
+[TARGET_ASM_OUTPUT_ANCHOR]
+
+[TARGET_ASM_OUTPUT_IDENT]
+.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
+
+ Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
+ directive, or the equivalent directive or pragma in non-C-family languages.
+ If this hook is not defined, nothing is output for the :samp:`#ident`
+ directive.
+
+[TARGET_ASM_OUTPUT_IDENT]
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
+
+ If defined, this target hook is a function which outputs a DTP-relative
+ reference to the given TLS symbol of the specified size.
+
+[TARGET_ASM_OUTPUT_DWARF_DTPREL]
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
+
+ If defined, this target hook is a function which is executed just after the
+ output of assembler code for :samp:`{insn}`, to change the mode of the assembler
+ if necessary.
+
+ Here the argument :samp:`{opvec}` is the vector containing the operands
+ extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
+ elements of the vector which contain meaningful data for this insn.
+ The contents of this vector are what was used to convert the insn
+ template into assembler code, so you can change the assembler mode
+ by checking the contents of the vector.
+
+[TARGET_ASM_FINAL_POSTSCAN_INSN]
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
+
+ This hook is called by ``assemble_trampoline_template`` to output,
+ on the stream :samp:`{f}`, assembler code for a block of data that contains
+ the constant parts of a trampoline. This code should not include a
+ label---the label is taken care of automatically.
+
+ If you do not define this hook, it means no template is needed
+ for the target. Do not define this hook on systems where the block move
+ code to copy the trampoline into place would be larger than the code
+ to generate it on the spot.
+
+[TARGET_ASM_TRAMPOLINE_TEMPLATE]
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
+
+ Output DWARF debugging information which indicates that filename
+ :samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
+
+ This target hook need not be defined if the standard form of output
+ for the file format in use is appropriate.
+
+[TARGET_ASM_OUTPUT_SOURCE_FILENAME]
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
+
+ A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
+ can't deal with, and output assembly code to :samp:`{file}` corresponding to
+ the pattern :samp:`{x}`. This may be used to allow machine-dependent
+ ``UNSPEC`` s to appear within constants.
+
+ If target hook fails to recognize a pattern, it must return ``false``,
+ so that a standard error message is printed. If it prints an error message
+ itself, by calling, for example, ``output_operand_lossage``, it may just
+ return ``true``.
+
+[TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
+
+ Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
+ ``assemble_name``, but in memory rather than to a file stream, returning
+ result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
+ default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
+ then prepends the ``USER_LABEL_PREFIX``, if any.
+
+[TARGET_MANGLE_ASSEMBLER_NAME]
+
+[TARGET_SCHED_ADJUST_COST]
+.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
+
+ This function corrects the value of :samp:`{cost}` based on the
+ relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
+ dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
+ value. The default is to make no adjustment to :samp:`{cost}`. This can be
+ used for example to specify to the scheduler using the traditional pipeline
+ description that an output- or anti-dependence does not incur the same cost
+ as a data-dependence. If the scheduler using the automaton based pipeline
+ description, the cost of anti-dependence is zero and the cost of
+ output-dependence is maximum of one and the difference of latency
+ times of the first and the second insns. If these values are not
+ acceptable, you could use the hook to modify them too. See also
+ see :ref:`processor-pipeline-description`.
+
+[TARGET_SCHED_ADJUST_COST]
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
+
+ This hook adjusts the integer scheduling priority :samp:`{priority}` of
+ :samp:`{insn}`. It should return the new priority. Increase the priority to
+ execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
+ later. Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+[TARGET_SCHED_ADJUST_PRIORITY]
+
+[TARGET_SCHED_ISSUE_RATE]
+.. function:: int TARGET_SCHED_ISSUE_RATE (void)
+
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ Although the insn scheduler can define itself the possibility of issue
+ an insn on the same cycle, the value can serve as an additional
+ constraint to issue insns on the same simulated processor cycle (see
+ hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
+ This value must be constant over the entire compilation. If you need
+ it to vary depending on what the instructions are, you must use
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`.
+
+[TARGET_SCHED_ISSUE_RATE]
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
+
+ This hook is executed by the scheduler after it has scheduled an insn
+ from the ready list. It should return the number of insns which can
+ still be issued in the current cycle. The default is
+ :samp:`{more} - 1` for insns other than ``CLOBBER`` and
+ ``USE``, which normally are not counted against the issue rate.
+ You should define this hook if some insns take more machine resources
+ than others, so that fewer insns can follow them in the same cycle.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
+ was scheduled.
+
+[TARGET_SCHED_VARIABLE_ISSUE]
+
+[TARGET_SCHED_INIT]
+.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
+
+ This hook is executed by the scheduler at the beginning of each block of
+ instructions that are to be scheduled. :samp:`{file}` is either a null
+ pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
+ is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{max_ready}` is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to allocate
+ scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
+
+[TARGET_SCHED_INIT]
+
+[TARGET_SCHED_FINISH]
+.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
+
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
+ is either a null pointer, or a stdio stream to write any debug output
+ to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH]
+
+[TARGET_SCHED_INIT_GLOBAL]
+.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
+
+ This hook is executed by the scheduler after function level initializations.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+ :samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
+
+[TARGET_SCHED_INIT_GLOBAL]
+
+[TARGET_SCHED_FINISH_GLOBAL]
+.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
+
+ This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
+ :samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
+
+[TARGET_SCHED_FINISH_GLOBAL]
+
+[TARGET_SCHED_REORDER]
+.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ This hook is executed by the scheduler after it has scheduled the ready
+ list, to allow the machine description to reorder it (for example to
+ combine two small instructions together on :samp:`VLIW` machines).
+ :samp:`{file}` is either a null pointer, or a stdio stream to write any
+ debug output to. :samp:`{verbose}` is the verbose level provided by
+ :option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
+ list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
+ a pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ :samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
+ is the timer tick of the scheduler. You may modify the ready list and
+ the number of ready insns. The return value is the number of insns that
+ can issue this cycle; normally this is just ``issue_rate``. See also
+ :samp:`TARGET_SCHED_REORDER2`.
+
+[TARGET_SCHED_REORDER]
+
+[TARGET_SCHED_REORDER2]
+.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
+
+ Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
+ function is called whenever the scheduler starts a new cycle. This one
+ is called once per iteration over a cycle, immediately after
+ :samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
+ return the number of insns to be scheduled in the same cycle. Defining
+ this hook can be useful if there are frequent situations where
+ scheduling one insn causes other insns to become ready in the same
+ cycle. These other insns can then be taken into account properly.
+
+[TARGET_SCHED_REORDER2]
+
+[TARGET_SCHED_MACRO_FUSION_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
+
+ This hook is used to check whether target platform supports macro fusion.
+
+[TARGET_SCHED_MACRO_FUSION_P]
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
+
+ This hook is used to check whether two insns should be macro fused for
+ a target microarchitecture. If this hook returns true for the given insn pair
+ (:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
+ group, and they will not be scheduled apart. The two insns will be either
+ two SET insns or a compare and a conditional jump and this hook should
+ validate any dependencies needed to fuse the two insns together.
+
+[TARGET_SCHED_MACRO_FUSION_PAIR_P]
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
+
+ This hook is called after evaluation forward dependencies of insns in
+ chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
+ correspondingly) but before insns scheduling of the insn chain. For
+ example, it can be used for better insn classification if it requires
+ analysis of dependencies. This hook can use backward and forward
+ dependencies of the insn scheduler because they are already
+ calculated.
+
+[TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
+
+ The hook can be used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
+
+ The hook returns an RTL insn. The automaton state used in the
+ pipeline hazard recognizer is changed as if the insn were scheduled
+ when the new simulated processor cycle starts. Usage of the hook may
+ simplify the automaton pipeline description for some VLIW
+ processors. If the hook is defined, it is used only for the automaton
+ based pipeline description. The default is not to change the state
+ when the new simulated processor cycle starts.
+
+[TARGET_SCHED_DFA_PRE_CYCLE_INSN]
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
+ used to initialize data used by the previous hook.
+
+[TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
+
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to changed the state as if the insn were scheduled when the new
+ simulated processor cycle finishes.
+
+[TARGET_SCHED_DFA_POST_CYCLE_INSN]
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
+
+ The hook to notify target that the current simulated cycle is about to finish.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
+
+ The hook to notify target that new simulated cycle has just started.
+ The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
+ to change the state in more complicated situations - e.g., when advancing
+ state on a single insn is not enough.
+
+[TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
+
+ This hook controls better choosing an insn from the ready insn queue
+ for the DFA-based insn scheduler. Usually the scheduler
+ chooses the first insn from the queue. If the hook returns a positive
+ value, an additional scheduler code tries all permutations of
+ :samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
+ subsequent ready insns to choose an insn whose issue will result in
+ maximal number of issued insns on the same cycle. For the
+ VLIW processor, the code could actually solve the problem of
+ packing simple insns into the VLIW insn. Of course, if the
+ rules of VLIW packing are described in the automaton.
+
+ This code also could be used for superscalar RISC
+ processors. Let us consider a superscalar RISC processor
+ with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
+ :samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
+ :samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
+ processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
+ :samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
+ until the next cycle. If the scheduler issues the 3rd insn the first,
+ the processor could issue all 3 insns per cycle.
+
+ Actually this code demonstrates advantages of the automaton based
+ pipeline hazard recognizer. We try quickly and easy many insn
+ schedules to choose the best one.
+
+ The default is no multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
+
+ This hook controls what insns from the ready insn queue will be
+ considered for the multipass insn scheduling. If the hook returns
+ zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
+ Positive return values will remove :samp:`{insn}` from consideration on
+ the current round of multipass scheduling.
+ Negative return values will remove :samp:`{insn}` from consideration for given
+ number of cycles.
+ Backends should be careful about returning non-zero for highest priority
+ instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
+ to allow backends make correct judgements.
+
+ The default is that any ready insns can be chosen to be issued.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
+
+ This hook prepares the target backend for a new round of multipass
+ scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
+
+ This hook is called when multipass scheduling evaluates instruction INSN.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
+
+ This is called when multipass scheduling backtracks from evaluation of
+ an instruction.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
+
+ This hook notifies the target about the result of the concluded current
+ round of multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
+
+ This hook initializes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
+
+ This hook finalizes target-specific data used in multipass scheduling.
+
+[TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
+
+ This hook is called by the insn scheduler before issuing :samp:`{insn}`
+ on cycle :samp:`{clock}`. If the hook returns nonzero,
+ :samp:`{insn}` is not issued on this processor cycle. Instead,
+ the processor cycle is advanced. If \* :samp:`{sort_p}`
+ is zero, the insn ready queue is not sorted on the new cycle
+ start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
+ verbosity level to use for debugging output.
+ :samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
+ processor cycle on which the previous insn has been issued,
+ and the current processor cycle.
+
+[TARGET_SCHED_DFA_NEW_CYCLE]
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
+
+ This hook is used to define which dependences are considered costly by
+ the target, so costly that it is not advisable to schedule the insns that
+ are involved in the dependence too close to one another. The parameters
+ to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
+ being evaluated. The second parameter :samp:`{cost}` is the cost of the
+ dependence as estimated by the scheduler, and the third
+ parameter :samp:`{distance}` is the distance in cycles between the two insns.
+ The hook returns ``true`` if considering the distance between the two
+ insns the dependence between them is considered costly by the target,
+ and ``false`` otherwise.
+
+ Defining this hook can be useful in multiple-issue out-of-order machines,
+ where (a) it's practically hopeless to predict the actual data/resource
+ delays, however: (b) there's a better chance to predict the actual grouping
+ that will be formed, and (c) correctly emulating the grouping can be very
+ important. In such targets one may want to allow issuing dependent insns
+ closer to one another---i.e., closer than the dependence distance; however,
+ not in cases of 'costly dependences', which this hooks allows to define.
+
+[TARGET_SCHED_IS_COSTLY_DEPENDENCE]
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
+
+ This hook is called by the insn scheduler after emitting a new instruction to
+ the instruction stream. The hook notifies a target backend to extend its
+ per instruction data structures.
+
+[TARGET_SCHED_H_I_D_EXTENDED]
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
+
+ Return a pointer to a store large enough to hold target scheduling context.
+
+[TARGET_SCHED_ALLOC_SCHED_CONTEXT]
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
+
+ Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
+ It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
+ beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
+
+[TARGET_SCHED_INIT_SCHED_CONTEXT]
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
+
+ Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
+
+[TARGET_SCHED_SET_SCHED_CONTEXT]
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
+
+ Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_CLEAR_SCHED_CONTEXT]
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
+
+ Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
+
+[TARGET_SCHED_FREE_SCHED_CONTEXT]
+
+[TARGET_SCHED_SPECULATE_INSN]
+.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
+
+ This hook is called by the insn scheduler when :samp:`{insn}` has only
+ speculative dependencies and therefore can be scheduled speculatively.
+ The hook is used to check if the pattern of :samp:`{insn}` has a speculative
+ version and, in case of successful check, to generate that speculative
+ pattern. The hook should return 1, if the instruction has a speculative form,
+ or -1, if it doesn't. :samp:`{request}` describes the type of requested
+ speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
+ the generated speculative pattern.
+
+[TARGET_SCHED_SPECULATE_INSN]
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
+
+ This hook is called by the insn scheduler during generation of recovery code
+ for :samp:`{insn}`. It should return ``true``, if the corresponding check
+ instruction should branch to recovery code, or ``false`` otherwise.
+
+[TARGET_SCHED_NEEDS_BLOCK_P]
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
+
+ This hook is called by the insn scheduler to generate a pattern for recovery
+ check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
+ speculative instruction for which the check should be generated.
+ :samp:`{label}` is either a label of a basic block, where recovery code should
+ be emitted, or a null pointer, when requested check doesn't branch to
+ recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
+ a pattern for a branchy check corresponding to a simple check denoted by
+ :samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
+
+[TARGET_SCHED_GEN_SPEC_CHECK]
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
+
+ This hook is used by the insn scheduler to find out what features should be
+ enabled/used.
+ The structure \* :samp:`{spec_info}` should be filled in by the target.
+ The structure describes speculation types that can be used in the scheduler.
+
+[TARGET_SCHED_SET_SCHED_FLAGS]
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
+
+ Some instructions should never be speculated by the schedulers, usually
+ because the instruction is too expensive to get this wrong. Often such
+ instructions have long latency, and often they are not fully modeled in the
+ pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
+ should not be speculated.
+
+[TARGET_SCHED_CAN_SPECULATE_INSN]
+
+[TARGET_SCHED_SMS_RES_MII]
+.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
+
+ This hook is called by the swing modulo scheduler to calculate a
+ resource-based lower bound which is based on the resources available in
+ the machine and the resources required by each instruction. The target
+ backend can use :samp:`{g}` to calculate such bound. A very simple lower
+ bound will be used in case this hook is not implemented: the total number
+ of instructions divided by the issue rate.
+
+[TARGET_SCHED_SMS_RES_MII]
+
+[TARGET_SCHED_DISPATCH_DO]
+.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It performs the operation specified
+ in its second parameter.
+
+[TARGET_SCHED_DISPATCH_DO]
+
+[TARGET_SCHED_DISPATCH]
+.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
+
+ This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
+ is supported in hardware and the condition specified in the parameter is true.
+
+[TARGET_SCHED_DISPATCH]
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
+
+ True if the processor has an exposed pipeline, which means that not just
+ the order of instructions is important for correctness when scheduling, but
+ also the latencies of operations.
+
+[TARGET_SCHED_EXPOSED_PIPELINE]
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
+
+ This hook is called by tree reassociator to determine a level of
+ parallelism required in output calculations chain.
+
+[TARGET_SCHED_REASSOCIATION_WIDTH]
+
+[TARGET_SCHED_FUSION_PRIORITY]
+.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
+
+ This hook is called by scheduling fusion pass. It calculates fusion
+ priorities for each instruction passed in by parameter. The priorities
+ are returned via pointer parameters.
+
+ :samp:`{insn}` is the instruction whose priorities need to be calculated.
+ :samp:`{max_pri}` is the maximum priority can be returned in any cases.
+ :samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
+ fusion priority should be calculated and returned.
+ :samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
+ should be calculated and returned.
+
+ Same :samp:`{fusion_pri}` should be returned for instructions which should
+ be scheduled together. Different :samp:`{pri}` should be returned for
+ instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
+ sort key, :samp:`{pri}` is the minor sort key. All instructions will be
+ scheduled according to the two priorities. All priorities calculated
+ should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
+ false dependencies, :samp:`{fusion_pri}` of instructions which need to be
+ scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
+ instructions.
+
+ Given below example:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4]
+ add r4, r4, r10
+ ldr r15, [r2, 8]
+ sub r5, r5, r15
+ ldr r11, [r1, 0]
+ add r4, r4, r11
+ ldr r16, [r2, 12]
+ sub r5, r5, r16
+
+ On targets like ARM/AArch64, the two pairs of consecutive loads should be
+ merged. Since peephole2 pass can't help in this case unless consecutive
+ loads are actually next to each other in instruction flow. That's where
+ this scheduling fusion pass works. This hook calculates priority for each
+ instruction based on its fustion type, like:
+
+ .. code-block:: c++
+
+ ldr r10, [r1, 4] ; fusion_pri=99, pri=96
+ add r4, r4, r10 ; fusion_pri=100, pri=100
+ ldr r15, [r2, 8] ; fusion_pri=98, pri=92
+ sub r5, r5, r15 ; fusion_pri=100, pri=100
+ ldr r11, [r1, 0] ; fusion_pri=99, pri=100
+ add r4, r4, r11 ; fusion_pri=100, pri=100
+ ldr r16, [r2, 12] ; fusion_pri=98, pri=88
+ sub r5, r5, r16 ; fusion_pri=100, pri=100
+
+ Scheduling fusion pass then sorts all ready to issue instructions according
+ to the priorities. As a result, instructions of same fusion type will be
+ pushed together in instruction flow, like:
+
+ .. code-block:: c++
+
+ ldr r11, [r1, 0]
+ ldr r10, [r1, 4]
+ ldr r15, [r2, 8]
+ ldr r16, [r2, 12]
+ add r4, r4, r10
+ sub r5, r5, r15
+ add r4, r4, r11
+ sub r5, r5, r16
+
+ Now peephole2 pass can simply merge the two pairs of loads.
+
+ Since scheduling fusion pass relies on peephole2 to do real fusion
+ work, it is only enabled by default when peephole2 is in effect.
+
+ This is firstly introduced on ARM/AArch64 targets, please refer to
+ the hook implementation for how different fusion types are supported.
+
+[TARGET_SCHED_FUSION_PRIORITY]
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
+
+ This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
+ fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
+ :samp:`{simdlen}` field if it was previously 0.
+ :samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
+ :samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
+ not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
+ The hook should return 0 if SIMD clones shouldn't be emitted,
+ or number of :samp:`{vecsize_mangle}` variants that should be emitted.
+
+[TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
+
+[TARGET_SIMD_CLONE_ADJUST]
+.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
+
+ This hook should add implicit ``attribute(target("..."))`` attribute
+ to SIMD clone :samp:`{node}` if needed.
+
+[TARGET_SIMD_CLONE_ADJUST]
+
+[TARGET_SIMD_CLONE_USABLE]
+.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
+
+ This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
+ in vectorized loops in current function, or non-negative number if it is
+ usable. In that case, the smaller the number is, the more desirable it is
+ to use it.
+
+[TARGET_SIMD_CLONE_USABLE]
+
+[TARGET_SIMT_VF]
+.. function:: int TARGET_SIMT_VF (void)
+
+ Return number of threads in SIMT thread group on the target.
+
+[TARGET_SIMT_VF]
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
+
+ Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
+ device trait set, return 0 if not present in any OpenMP context in the
+ whole translation unit, or -1 if not present in the current OpenMP context
+ but might be present in another OpenMP context in the same TU.
+
+[TARGET_OMP_DEVICE_KIND_ARCH_ISA]
+
+[TARGET_GOACC_VALIDATE_DIMS]
+.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
+
+ This hook should check the launch dimensions provided for an OpenACC
+ compute region, or routine. Defaulted values are represented as -1
+ and non-constant values as 0. The :samp:`{fn_level}` is negative for the
+ function corresponding to the compute region. For a routine it is the
+ outermost level at which partitioned execution may be spawned. The hook
+ should verify non-default values. If DECL is NULL, global defaults
+ are being validated and unspecified defaults should be filled in.
+ Diagnostics should be issued as appropriate. Return
+ true, if changes have been made. You must override this hook to
+ provide dimensions larger than 1.
+
+[TARGET_GOACC_VALIDATE_DIMS]
+
+[TARGET_GOACC_DIM_LIMIT]
+.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
+
+ This hook should return the maximum size of a particular dimension,
+ or zero if unbounded.
+
+[TARGET_GOACC_DIM_LIMIT]
+
+[TARGET_GOACC_FORK_JOIN]
+.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
+
+ This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
+ function calls to target-specific gimple, or indicate whether they
+ should be retained. It is executed during the oacc_device_lower pass.
+ It should return true, if the call should be retained. It should
+ return false, if it is to be deleted (either because target-specific
+ gimple has been inserted before it, or there is no need for it).
+ The default hook returns false, if there are no RTL expanders for them.
+
+[TARGET_GOACC_FORK_JOIN]
+
+[TARGET_GOACC_REDUCTION]
+.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
+
+ This hook is used by the oacc_transform pass to expand calls to the
+ :samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
+ instructions. :samp:`{call}` is gimple statement containing the call to
+ the function. This hook removes statement :samp:`{call}` after the
+ expanded sequence has been inserted. This hook is also responsible
+ for allocating any storage for reductions when necessary.
+
+[TARGET_GOACC_REDUCTION]
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
+
+ This hook, if defined, is used by accelerator target back-ends to adjust
+ OpenACC variable declarations that should be made private to the given
+ parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
+ ``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
+ declarations at the ``gang`` level to reside in GPU shared memory.
+ :samp:`{loc}` may be used for diagnostic purposes.
+
+ You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
+ adjusted variable declaration needs to be expanded to RTL in a non-standard
+ way.
+
+[TARGET_GOACC_ADJUST_PRIVATE_DECL]
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
+
+ This hook, if defined, is used by accelerator target back-ends to expand
+ specially handled kinds of ``VAR_DECL`` expressions. A particular use is
+ to place variables with specific attributes inside special accelarator
+ memories. A return value of ``NULL`` indicates that the target does not
+ handle this ``VAR_DECL``, and normal RTL expanding is resumed.
+
+ Only define this hook if your accelerator target needs to expand certain
+ ``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
+ private variables at OpenACC device-lowering time using the
+ ``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
+
+[TARGET_GOACC_EXPAND_VAR_DECL]
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
+
+ Create a record used to propagate local-variable state from an active
+ worker to other workers. A possible implementation might adjust the type
+ of REC to place the new variable in shared GPU memory.
+
+ Presence of this target hook indicates that middle end neutering/broadcasting
+ be used.
+
+[TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
+
+ Lay out a fixed shared-memory region on the target. The LO and HI
+ arguments should be set to a range of addresses that can be used for worker
+ broadcasting. The dimensions, reduction size and gang-private size
+ arguments are for the current offload region.
+
+[TARGET_GOACC_SHARED_MEM_LAYOUT]
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
+
+ This hook should return the DECL of a function :samp:`{f}` that given an
+ address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
+ used to extract from two vectors the relevant data that resides in
+ :samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
+
+ The autovectorizer, when vectorizing a load operation from an address
+ :samp:`{addr}` that may be unaligned, will generate two vector loads from
+ the two aligned addresses around :samp:`{addr}`. It then generates a
+ ``REALIGN_LOAD`` operation to extract the relevant data from the
+ two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
+ :samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
+ the third argument, :samp:`{OFF}`, defines how the data will be extracted
+ from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
+ :samp:`{v2}` ; otherwise, the returned vector is composed from the last
+ :samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
+ :samp:`{OFF}` elements of :samp:`{v2}`.
+
+ If this hook is defined, the autovectorizer will generate a call
+ to :samp:`{f}` (using the DECL tree that this hook returns) and will
+ use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
+ ``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
+ should comply with the semantics expected by ``REALIGN_LOAD``
+ described above.
+ If this hook is not defined, then :samp:`{addr}` will be used as
+ the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
+ log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
+
+[TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of the function with the ``combined_fn`` code
+ :samp:`{code}` or ``NULL_TREE`` if such a function is not available.
+ The return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
+
+ This hook should return the decl of a function that implements the
+ vectorized variant of target built-in function ``fndecl``. The
+ return type of the vectorized function shall be of vector type
+ :samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
+
+[TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
+
+ Returns cost of different scalar or vector statements for vectorization cost model.
+ For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
+ misalignment value (:samp:`{misalign}`).
+
+[TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook returns the preferred alignment in bits for accesses to
+ vectors of type :samp:`{type}` in vectorized code. This might be less than
+ or greater than the ABI-defined value returned by
+ ``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
+ a single element, in which case the vectorizer will not try to optimize
+ for alignment.
+
+ The default hook returns ``TYPE_ALIGN (type)``, which is
+ correct for most targets.
+
+[TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
+
+ Return true if vector alignment is reachable (by peeling N iterations)
+ for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
+ access using :samp:`{type}` is known to be naturally aligned.
+
+[TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
+
+ This hook is used to test whether the target can permute up to two
+ vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
+ producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
+ a permutation.
+
+ When the hook is being used to test whether the target supports a permutation,
+ :samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
+ to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
+ :samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
+ :samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
+ vector instead of two.
+
+ Return true if the operation is possible, emitting instructions for it
+ if rtxes are provided.
+
+ .. index:: vec_permm instruction pattern
+
+ If the hook returns false for a mode with multibyte elements, GCC will
+ try the equivalent byte operation. If that also fails, it will try forcing
+ the selector into a register and using the :samp:`{vec_perm {mode} }`
+ instruction pattern. There is no need for the hook to handle these two
+ implementation approaches itself.
+
+[TARGET_VECTORIZE_VEC_PERM_CONST]
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
+
+ This hook should return true if the target supports misaligned vector
+ store/load of a specific factor denoted in the :samp:`{misalignment}`
+ parameter. The vector store/load should be of machine mode :samp:`{mode}` and
+ the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
+ parameter is true if the memory access is defined in a packed struct.
+
+[TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
+
+ This hook should return the preferred mode for vectorizing scalar
+ mode :samp:`{mode}`. The default is
+ equal to ``word_mode``, because the vectorizer can do some
+ transformations even in absence of specialized SIMD hardware.
+
+[TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
+
+ This hook should return the preferred mode to split the final reduction
+ step on :samp:`{mode}` to. The reduction is then carried out reducing upper
+ against lower halves of vectors recursively until the specified mode is
+ reached. The default is :samp:`{mode}` which means no splitting.
+
+[TARGET_VECTORIZE_SPLIT_REDUCTION]
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
+
+ If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
+ is not the only approach worth considering, this hook should add one mode to
+ :samp:`{modes}` for each useful alternative approach. These modes are then
+ passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
+ for a given element mode.
+
+ The modes returned in :samp:`{modes}` should use the smallest element mode
+ possible for the vectorization approach that they represent, preferring
+ integer modes over floating-poing modes in the event of a tie. The first
+ mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
+ element mode.
+
+ If :samp:`{all}` is true, add suitable vector modes even when they are generally
+ not expected to be worthwhile.
+
+ The hook returns a bitmask of flags that control how the modes in
+ :samp:`{modes}` are used. The flags are:
+
+ .. envvar:: VECT_COMPARE_COSTS
+
+ Tells the loop vectorizer to try all the provided modes and pick the one
+ with the lowest cost. By default the vectorizer will choose the first
+ mode that works.
+
+ The hook does not need to do anything if the vector returned by
+ ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
+ for autovectorization. The default implementation adds no modes and
+ returns 0.
+
+[TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
+
+[TARGET_VECTORIZE_RELATED_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
+
+ If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
+ to operate on elements of mode :samp:`{element_mode}`, return the vector mode
+ it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
+ the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
+ size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
+ ``opt_machine_mode`` if there is no supported vector mode with the
+ required properties.
+
+ There is no prescribed way of handling the case in which :samp:`{nunits}`
+ is zero. One common choice is to pick a vector mode with the same size
+ as :samp:`{vector_mode}` ; this is the natural choice if the target has a
+ fixed vector size. Another option is to choose a vector mode with the
+ same number of elements as :samp:`{vector_mode}` ; this is the natural choice
+ if the target has a fixed number of elements. Alternatively, the hook
+ might choose a middle ground, such as trying to keep the number of
+ elements as similar as possible while applying maximum and minimum
+ vector sizes.
+
+ The default implementation uses ``mode_for_vector`` to find the
+ requested mode, returning a mode with the same size as :samp:`{vector_mode}`
+ when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
+
+[TARGET_VECTORIZE_RELATED_MODE]
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
+
+ Return the mode to use for a vector mask that holds one boolean
+ result for each element of vector mode :samp:`{mode}`. The returned mask mode
+ can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
+ booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
+ ``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
+ mask mode exists.
+
+ The default implementation returns a ``MODE_VECTOR_INT`` with the
+ same size and number of elements as :samp:`{mode}`, if such a mode exists.
+
+[TARGET_VECTORIZE_GET_MASK_MODE]
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
+
+ This hook returns true if masked internal function :samp:`{ifn}` (really of
+ type ``internal_fn``) should be considered expensive when the mask is
+ all zeros. GCC can then try to branch around the instruction instead.
+
+[TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
+ is the vector type of the load and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize gather
+ loads.
+
+[TARGET_VECTORIZE_BUILTIN_GATHER]
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
+
+ Target builtin that implements vector scatter operation. :samp:`{vectype}`
+ is the vector type of the store and :samp:`{index_type}` is scalar type of
+ the index, scaled by :samp:`{scale}`.
+ The default is ``NULL_TREE`` which means to not vectorize scatter
+ stores.
+
+[TARGET_VECTORIZE_BUILTIN_SCATTER]
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
+
+ This hook should initialize target-specific data structures in preparation
+ for modeling the costs of vectorizing a loop or basic block. The default
+ allocates three unsigned integers for accumulating costs for the prologue,
+ body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
+ non-NULL, it identifies the loop being vectorized; otherwise a single block
+ is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
+ current cost model is for the scalar version of a loop or block; otherwise
+ it is for the vector version.
+
+[TARGET_VECTORIZE_CREATE_COSTS]
+
+[TARGET_PREFERRED_ELSE_VALUE]
+.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
+
+ This hook returns the target's preferred final argument for a call
+ to conditional internal function :samp:`{ifn}` (really of type
+ ``internal_fn``). :samp:`{type}` specifies the return type of the
+ function and :samp:`{ops}` are the operands to the conditional operation,
+ of which there are :samp:`{nops}`.
+
+ For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
+ a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
+ and :samp:`{ops}[1]` are conditionally added together.
+
+ This hook is only relevant if the target supports conditional patterns
+ like ``cond_addm``. The default implementation returns a zero
+ constant of type :samp:`{type}`.
+
+[TARGET_PREFERRED_ELSE_VALUE]
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+.. function:: void TARGET_RECORD_OFFLOAD_SYMBOL (tree)
+
+ Used when offloaded functions are seen in the compilation unit and no named
+ sections are available. It is called once for each symbol that must be
+ recorded in the offload function and variable table.
+
+[TARGET_RECORD_OFFLOAD_SYMBOL]
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
+
+ If defined, this target hook specifies the absolute biggest alignment
+ that a type or variable can have on this machine, otherwise,
+ ``BIGGEST_ALIGNMENT`` is used.
+
+[TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
+
+ This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
+ but is called when the optimize level is changed via an attribute or
+ pragma or when it is reset at the end of the code affected by the
+ attribute or pragma. It is not called at the beginning of compilation
+ when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
+ actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
+
+[TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
+
+[TARGET_OFFLOAD_OPTIONS]
+.. function:: char * TARGET_OFFLOAD_OPTIONS (void)
+
+ Used when writing out the list of options into an LTO file. It should
+ translate any relevant target-specific options (such as the ABI in use)
+ into one of the :option:`-foffload` options that exist as a common interface
+ to express such options. It should return a string containing these options,
+ separated by spaces, which the caller will free.
+
+[TARGET_OFFLOAD_OPTIONS]
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
+
+ This target hook should return the mode to be used for the return value
+ of compare instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_CMP_RETURN_MODE]
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
+
+ This target hook should return the mode to be used for the shift count operand
+ of shift instructions expanded to libgcc calls. If not defined
+ ``word_mode`` is returned which is the right choice for a majority of
+ targets.
+
+[TARGET_LIBGCC_SHIFT_COUNT_MODE]
+
+[TARGET_UNWIND_WORD_MODE]
+.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
+
+ Return machine mode to be used for ``_Unwind_Word`` type.
+ The default is to use ``word_mode``.
+
+[TARGET_UNWIND_WORD_MODE]
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
+
+ Define this target hook if the merging of decl attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
+ :samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
+ when this is needed are when one attribute overrides another, or when an
+ attribute is nullified by a subsequent definition. This function may
+ call ``merge_attributes`` to handle machine-independent merging.
+
+ .. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
+
+ If the only target-specific handling you require is :samp:`dllimport`
+ for Microsoft Windows targets, you should define the macro
+ ``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
+ will then define a function called
+ ``merge_dllimport_decl_attributes`` which can then be defined as
+ the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
+ add ``handle_dll_attribute`` in the attribute table for your port
+ to perform initial processing of the :samp:`dllimport` and
+ :samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
+ :samp:`i386/i386.cc`, for example.
+
+[TARGET_MERGE_DECL_ATTRIBUTES]
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
+
+ Define this target hook if the merging of type attributes needs special
+ handling. If defined, the result is a list of the combined
+ ``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
+ that ``comptypes`` has already been called and returned 1. This
+ function may call ``merge_attributes`` to handle machine-independent
+ merging.
+
+[TARGET_MERGE_TYPE_ATTRIBUTES]
+
+[TARGET_ATTRIBUTE_TABLE]
+.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+
+ If defined, this target hook points to an array of :samp:`struct
+ attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
+ specific attributes for this target and some of the restrictions on the
+ entities to which these attributes are applied and the arguments they
+ take.
+
+[TARGET_ATTRIBUTE_TABLE]
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
+
+ If defined, this target hook is a function which returns true if the
+ machine-specific attribute named :samp:`{name}` expects an identifier
+ given as its first argument to be passed on as a plain identifier, not
+ subjected to name lookup. If this is not defined, the default is
+ false for all machine-specific attributes.
+
+[TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
+
+ If defined, this target hook is a function which returns zero if the attributes on
+ :samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
+ and two if they are nearly compatible (which causes a warning to be
+ generated). If this is not defined, machine-specific attributes are
+ supposed always to be compatible.
+
+[TARGET_COMP_TYPE_ATTRIBUTES]
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
+
+ If defined, this target hook is a function which assigns default attributes to
+ the newly defined :samp:`{type}`.
+
+[TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
+
+[TARGET_INSERT_ATTRIBUTES]
+.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
+
+ Define this target hook if you want to be able to add attributes to a decl
+ when it is being created. This is normally useful for back ends which
+ wish to implement a pragma by using the attributes which correspond to
+ the pragma's effect. The :samp:`{node}` argument is the decl which is being
+ created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
+ for this decl. The list itself should not be modified, since it may be
+ shared with other decls, but attributes may be chained on the head of
+ the list and ``*attr_ptr`` modified to point to the new
+ attributes, or a copy of the list may be made if further changes are
+ needed.
+
+[TARGET_INSERT_ATTRIBUTES]
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
+
+ Define this target hook if you want to be able to perform additional
+ target-specific processing of an attribute which is handled generically
+ by a front end. The arguments are the same as those which are passed to
+ attribute handlers. So far this only affects the :samp:`{noinit}` and
+ :samp:`{section}` attribute.
+
+[TARGET_HANDLE_GENERIC_ATTRIBUTE]
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
+
+ .. index:: inlining
+
+ This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
+ into the current function, despite its having target-specific
+ attributes, ``false`` otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
+
+[TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
+
+ This target hook returns ``true`` if bit-fields in the given
+ :samp:`{record_type}` are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of nonzero size. If this hook returns ``true``,
+ other macros that control bit-field layout are ignored.
+
+ When a bit-field is inserted into a packed record, the whole size
+ of the underlying type is used by one or more same-size adjacent
+ bit-fields (that is, if its long:3, 32 bits is used in the record,
+ and any additional adjacent long bit-fields are packed into the same
+ chunk of 32 bits. However, if the size changes, a new field of that
+ size is allocated). In an unpacked record, this is the same as using
+ alignment, but not equivalent when packing.
+
+ If both MS bit-fields and :samp:`__attribute__((packed))` are used,
+ the latter will take precedence. If :samp:`__attribute__((packed))` is
+ used on a single field when MS bit-fields are in use, it will take
+ precedence for that field, but the alignment of the rest of the structure
+ may affect its placement.
+
+[TARGET_MS_BITFIELD_LAYOUT_P]
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
+
+ Returns true if the target supports IEEE 754 floating-point exceptions
+ and rounding modes, false otherwise. This is intended to relate to the
+ ``float`` and ``double`` types, but not necessarily ``long double``.
+ By default, returns true if the ``adddf3`` instruction pattern is
+ available and false otherwise, on the assumption that hardware floating
+ point supports exceptions and rounding modes but software floating point
+ does not.
+
+[TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
+
+ Returns true if the target supports decimal floating point.
+
+[TARGET_DECIMAL_FLOAT_SUPPORTED_P]
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
+
+ Returns true if the target supports fixed-point arithmetic.
+
+[TARGET_FIXED_POINT_SUPPORTED_P]
+
+[TARGET_ALIGN_ANON_BITFIELD]
+.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
+
+ When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
+ whether unnamed bitfields affect the alignment of the containing
+ structure. The hook should return true if the structure should inherit
+ the alignment requirements of an unnamed bitfield's type.
+
+[TARGET_ALIGN_ANON_BITFIELD]
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
+
+ This target hook should return ``true`` if accesses to volatile bitfields
+ should use the narrowest mode possible. It should return ``false`` if
+ these accesses should use the bitfield container type.
+
+ The default is ``false``.
+
+[TARGET_NARROW_VOLATILE_BITFIELD]
+
+[TARGET_INIT_BUILTINS]
+.. function:: void TARGET_INIT_BUILTINS (void)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that performs the
+ necessary setup.
+
+ Machine specific built-in functions can be useful to expand special machine
+ instructions that would otherwise not normally be generated because
+ they have no equivalent in the source language (for example, SIMD vector
+ instructions or prefetch instructions).
+
+ To create a built-in function, call the function
+ ``lang_hooks.builtin_function``
+ which is defined by the language front end. You can use any type nodes set
+ up by ``build_common_tree_nodes`` ;
+ only language front ends that use those two functions will call
+ :samp:`TARGET_INIT_BUILTINS`.
+
+[TARGET_INIT_BUILTINS]
+
+[TARGET_BUILTIN_DECL]
+.. function:: tree TARGET_BUILTIN_DECL (unsigned code, bool initialize_p)
+
+ Define this hook if you have any machine-specific built-in functions
+ that need to be defined. It should be a function that returns the
+ builtin function declaration for the builtin function code :samp:`{code}`.
+ If there is no such builtin and it cannot be initialized at this time
+ if :samp:`{initialize_p}` is true the function should return ``NULL_TREE``.
+ If :samp:`{code}` is out of range the function should return
+ ``error_mark_node``.
+
+[TARGET_BUILTIN_DECL]
+
+[TARGET_EXPAND_BUILTIN]
+.. function:: rtx TARGET_EXPAND_BUILTIN (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore)
+
+ Expand a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{exp}` is the expression for the
+ function call; the result should go to :samp:`{target}` if that is
+ convenient, and have mode :samp:`{mode}` if that is convenient.
+ :samp:`{subtarget}` may be used as the target for computing one of
+ :samp:`{exp}` 's operands. :samp:`{ignore}` is nonzero if the value is to be
+ ignored. This function should return the result of the call to the
+ built-in function.
+
+[TARGET_EXPAND_BUILTIN]
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+.. function:: tree TARGET_RESOLVE_OVERLOADED_BUILTIN (unsigned int loc, tree fndecl, void *arglist)
+
+ Select a replacement for a machine specific built-in function that
+ was set up by :samp:`TARGET_INIT_BUILTINS`. This is done
+ *before* regular type checking, and so allows the target to
+ implement a crude form of function overloading. :samp:`{fndecl}` is the
+ declaration of the built-in function. :samp:`{arglist}` is the list of
+ arguments passed to the built-in function. The result is a
+ complete expression that implements the operation, usually
+ another ``CALL_EXPR``.
+ :samp:`{arglist}` really has type :samp:`VEC(tree,gc)*`
+
+[TARGET_RESOLVE_OVERLOADED_BUILTIN]
+
+[TARGET_CHECK_BUILTIN_CALL]
+.. function:: bool TARGET_CHECK_BUILTIN_CALL (location_t loc, vec<location_t> arg_loc, tree fndecl, tree orig_fndecl, unsigned int nargs, tree *args)
+
+ Perform semantic checking on a call to a machine-specific built-in
+ function after its arguments have been constrained to the function
+ signature. Return true if the call is valid, otherwise report an error
+ and return false.
+
+ This hook is called after ``TARGET_RESOLVE_OVERLOADED_BUILTIN``.
+ The call was originally to built-in function :samp:`{orig_fndecl}`,
+ but after the optional ``TARGET_RESOLVE_OVERLOADED_BUILTIN``
+ step is now to built-in function :samp:`{fndecl}`. :samp:`{loc}` is the
+ location of the call and :samp:`{args}` is an array of function arguments,
+ of which there are :samp:`{nargs}`. :samp:`{arg_loc}` specifies the location
+ of each argument.
+
+[TARGET_CHECK_BUILTIN_CALL]
+
+[TARGET_FOLD_BUILTIN]
+.. function:: tree TARGET_FOLD_BUILTIN (tree fndecl, int n_args, tree *argp, bool ignore)
+
+ Fold a call to a machine specific built-in function that was set up by
+ :samp:`TARGET_INIT_BUILTINS`. :samp:`{fndecl}` is the declaration of the
+ built-in function. :samp:`{n_args}` is the number of arguments passed to
+ the function; the arguments themselves are pointed to by :samp:`{argp}`.
+ The result is another tree, valid for both GIMPLE and GENERIC,
+ containing a simplified expression for the call's result. If
+ :samp:`{ignore}` is true the value will be ignored.
+
+[TARGET_FOLD_BUILTIN]
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+.. function:: bool TARGET_GIMPLE_FOLD_BUILTIN (gimple_stmt_iterator *gsi)
+
+ Fold a call to a machine specific built-in function that was set up
+ by :samp:`TARGET_INIT_BUILTINS`. :samp:`{gsi}` points to the gimple
+ statement holding the function call. Returns true if any change
+ was made to the GIMPLE stream.
+
+[TARGET_GIMPLE_FOLD_BUILTIN]
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+.. function:: int TARGET_COMPARE_VERSION_PRIORITY (tree decl1, tree decl2)
+
+ This hook is used to compare the target attributes in two functions to
+ determine which function's features get higher priority. This is used
+ during function multi-versioning to figure out the order in which two
+ versions must be dispatched. A function version with a higher priority
+ is checked for dispatching earlier. :samp:`{decl1}` and :samp:`{decl2}` are
+ the two function decls that will be compared.
+
+[TARGET_COMPARE_VERSION_PRIORITY]
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+.. function:: tree TARGET_GENERATE_VERSION_DISPATCHER_BODY (void *arg)
+
+ This hook is used to generate the dispatcher logic to invoke the right
+ function version at run-time for a given set of function versions.
+ :samp:`{arg}` points to the callgraph node of the dispatcher function whose
+ body must be generated.
+
+[TARGET_GENERATE_VERSION_DISPATCHER_BODY]
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+.. function:: tree TARGET_GET_FUNCTION_VERSIONS_DISPATCHER (void *decl)
+
+ This hook is used to get the dispatcher function for a set of function
+ versions. The dispatcher function is called to invoke the right function
+ version at run-time. :samp:`{decl}` is one version from a set of semantically
+ identical versions.
+
+[TARGET_GET_FUNCTION_VERSIONS_DISPATCHER]
+
+[TARGET_BUILTIN_RECIPROCAL]
+.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
+
+ This hook should return the DECL of a function that implements the
+ reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
+ ``NULL_TREE`` if such a function is not available.
+
+[TARGET_BUILTIN_RECIPROCAL]
+
+[TARGET_MANGLE_TYPE]
+.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
+
+ If your target defines any fundamental types, or any types your target
+ uses should be mangled differently from the default, define this hook
+ to return the appropriate encoding for these types as part of a C++
+ mangled name. The :samp:`{type}` argument is the tree structure representing
+ the type to be mangled. The hook may be applied to trees which are
+ not target-specific fundamental types; it should return ``NULL``
+ for all such types, as well as arguments it does not recognize. If the
+ return value is not ``NULL``, it must point to a statically-allocated
+ string constant.
+
+ Target-specific fundamental types might be new fundamental types or
+ qualified versions of ordinary fundamental types. Encode new
+ fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
+ is the name used for the type in source code, and :samp:`{n}` is the
+ length of :samp:`{name}` in decimal. Encode qualified versions of
+ ordinary types as :samp:`U{n}{name}{code}`, where
+ :samp:`{name}` is the name used for the type qualifier in source code,
+ :samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
+ code used to represent the unqualified version of this type. (See
+ ``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
+ codes.) In both cases the spaces are for clarity; do not include any
+ spaces in your string.
+
+ This hook is applied to types prior to typedef resolution. If the mangled
+ name for a particular type depends only on that type's main variant, you
+ can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
+ before mangling.
+
+ The default version of this hook always returns ``NULL``, which is
+ appropriate for a target that does not define any new fundamental
+ types.
+
+[TARGET_MANGLE_TYPE]
+
+[TARGET_INIT_LIBFUNCS]
+.. function:: void TARGET_INIT_LIBFUNCS (void)
+
+ This hook should declare additional library routines or rename
+ existing ones, using the functions ``set_optab_libfunc`` and
+ ``init_one_libfunc`` defined in :samp:`optabs.cc`.
+ ``init_optabs`` calls this macro after initializing all the normal
+ library routines.
+
+ The default is to do nothing. Most ports don't need to define this hook.
+
+[TARGET_INIT_LIBFUNCS]
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
+
+ If false (the default), internal library routines start with two
+ underscores. If set to true, these routines start with ``__gnu_``
+ instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
+ currently only affects functions defined in :samp:`libgcc2.c`. If this
+ is set to true, the :samp:`tm.h` file must also
+ ``#define LIBGCC2_GNU_PREFIX``.
+
+[TARGET_LIBFUNC_GNU_PREFIX]
+
+[TARGET_SECTION_TYPE_FLAGS]
+.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
+
+ Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
+ based on a variable or function decl, a section name, and whether or not the
+ declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
+ null, in which case read-write data should be assumed.
+
+ The default version of this function handles choosing code vs data,
+ read-only vs read-write data, and ``flag_pic``. You should only
+ need to override this if your target has special flags that might be
+ set via ``__attribute__``.
+
+[TARGET_SECTION_TYPE_FLAGS]
+
+[TARGET_LIBC_HAS_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
+
+ This hook determines whether a function from a class of functions
+ :samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
+ the caller asks for support for all standard (float, double, long double)
+ types. If :samp:`{type}` is non-NULL, the caller asks for support for a
+ specific type.
+
+[TARGET_LIBC_HAS_FUNCTION]
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
+
+ This hook determines whether a function from a class of functions
+ ``(enum function_class)``:samp:`{fcode}` has a fast implementation.
+
+[TARGET_LIBC_HAS_FAST_FUNCTION]
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+.. function:: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+
+ This target hook returns ``true`` past the point in which new jump
+ instructions could be created. On machines that require a register for
+ every jump such as the SHmedia ISA of SH5, this point would typically be
+ reload, so this target hook should be defined to a function such as:
+
+ .. code-block:: c++
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
+
+[TARGET_CANNOT_MODIFY_JUMPS_P]
+
+[TARGET_CAN_FOLLOW_JUMP]
+.. function:: bool TARGET_CAN_FOLLOW_JUMP (const rtx_insn *follower, const rtx_insn *followee)
+
+ FOLLOWER and FOLLOWEE are JUMP_INSN instructions;
+ return true if FOLLOWER may be modified to follow FOLLOWEE;
+ false, if it can't.
+ For example, on some targets, certain kinds of branches can't be made to
+ follow through a hot/cold partitioning.
+
+[TARGET_CAN_FOLLOW_JUMP]
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+.. function:: bool TARGET_HAVE_CONDITIONAL_EXECUTION (void)
+
+ This target hook returns true if the target supports conditional execution.
+ This target hook is required only when the target has several different
+ modes and they have different conditional execution capability, such as ARM.
+
+[TARGET_HAVE_CONDITIONAL_EXECUTION]
+
+[TARGET_GEN_CCMP_FIRST]
+.. function:: rtx TARGET_GEN_CCMP_FIRST (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1)
+
+ This function prepares to emit a comparison insn for the first compare in a
+ sequence of conditional comparisions. It returns an appropriate comparison
+ with ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+
+[TARGET_GEN_CCMP_FIRST]
+
+[TARGET_GEN_CCMP_NEXT]
+.. function:: rtx TARGET_GEN_CCMP_NEXT (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code)
+
+ This function prepares to emit a conditional comparison within a sequence
+ of conditional comparisons. It returns an appropriate comparison with
+ ``CC`` for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ The insns to prepare the compare are saved in :samp:`{prep_seq}` and the compare
+ insns are saved in :samp:`{gen_seq}`. They will be emitted when all the
+ compares in the conditional comparision are generated without error. The
+ :samp:`{prev}` expression is the result of a prior call to ``gen_ccmp_first``
+ or ``gen_ccmp_next``. It may return ``NULL`` if the combination of
+ :samp:`{prev}` and this comparison is not supported, otherwise the result must
+ be appropriate for passing to ``gen_ccmp_next`` or ``cbranch_optab``.
+ :samp:`{code}` is the ``rtx_code`` of the compare for :samp:`{op0}` and :samp:`{op1}`.
+ :samp:`{bit_code}` is ``AND`` or ``IOR``, which is the op on the compares.
+
+[TARGET_GEN_CCMP_NEXT]
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+.. function:: rtx TARGET_GEN_MEMSET_SCRATCH_RTX (machine_mode mode)
+
+ This hook should return an rtx for a scratch register in :samp:`{mode}` to
+ be used when expanding memset calls. The backend can use a hard scratch
+ register to avoid stack realignment when expanding memset. The default
+ is ``gen_reg_rtx``.
+
+[TARGET_GEN_MEMSET_SCRATCH_RTX]
+
+[TARGET_LOOP_UNROLL_ADJUST]
+.. function:: unsigned TARGET_LOOP_UNROLL_ADJUST (unsigned nunroll, class loop *loop)
+
+ This target hook returns a new value for the number of times :samp:`{loop}`
+ should be unrolled. The parameter :samp:`{nunroll}` is the number of times
+ the loop is to be unrolled. The parameter :samp:`{loop}` is a pointer to
+ the loop, which is going to be checked for unrolling. This target hook
+ is required only when the target has special constraints like maximum
+ number of memory accesses.
+
+[TARGET_LOOP_UNROLL_ADJUST]
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a legitimate constant for a
+ :samp:`{mode}` -mode immediate operand on the target machine. You can assume that
+ :samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
+
+ The default definition returns true.
+
+[TARGET_LEGITIMATE_CONSTANT_P]
+
+[TARGET_PRECOMPUTE_TLS_P]
+.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
+
+ This hook returns true if :samp:`{x}` is a TLS operand on the target
+ machine that should be pre-computed when used as the argument in a call.
+ You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
+ check this.
+
+ The default definition returns false.
+
+[TARGET_PRECOMPUTE_TLS_P]
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
+
+ This hook should return true if :samp:`{x}` is of a form that cannot (or
+ should not) be spilled to the constant pool. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version of this hook returns false.
+
+ The primary reason to define this hook is to prevent reload from
+ deciding that a non-legitimate constant would be better reloaded
+ from the constant pool instead of spilling and reloading a register
+ holding the constant. This restriction is often true of addresses
+ of TLS symbols for various targets.
+
+[TARGET_CANNOT_FORCE_CONST_MEM]
+
+[TARGET_COMMUTATIVE_P]
+.. function:: bool TARGET_COMMUTATIVE_P (const_rtx x, int outer_code)
+
+ This target hook returns ``true`` if :samp:`{x}` is considered to be commutative.
+ Usually, this is just COMMUTATIVE_P (:samp:`{x}`), but the HP PA doesn't consider
+ PLUS to be commutative inside a MEM. :samp:`{outer_code}` is the rtx code
+ of the enclosing rtl, if known, otherwise it is UNKNOWN.
+
+[TARGET_COMMUTATIVE_P]
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
+
+ This hook returns ``true`` if memory address :samp:`{addr}` in address
+ space :samp:`{addrspace}` can have
+ different meanings depending on the machine mode of the memory
+ reference it is used for or if the address is valid for some modes
+ but not others.
+
+ Autoincrement and autodecrement addresses typically have mode-dependent
+ effects because the amount of the increment or decrement is the size
+ of the operand being addressed. Some machines have other mode-dependent
+ addresses. Many RISC machines have no mode-dependent addresses.
+
+ You may assume that :samp:`{addr}` is a valid address for the machine.
+
+ The default version of this hook returns ``false``.
+
+[TARGET_MODE_DEPENDENT_ADDRESS_P]
+
+[TARGET_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
+
+ This hook is given an invalid memory address :samp:`{x}` for an
+ operand of mode :samp:`{mode}` and should try to return a valid memory
+ address.
+
+ .. index:: break_out_memory_refs
+
+ :samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
+ and :samp:`{oldx}` will be the operand that was given to that function to produce
+ :samp:`{x}`.
+
+ The code of the hook should not alter the substructure of
+ :samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
+ should return the new :samp:`{x}`.
+
+ It is not necessary for this hook to come up with a legitimate address,
+ with the exception of native TLS addresses (see :ref:`emulated-tls`).
+ The compiler has standard ways of doing so in all cases. In fact, if
+ the target supports only emulated TLS, it
+ is safe to omit this hook or make it return :samp:`{x}` if it cannot find
+ a valid way to legitimize the address. But often a machine-dependent
+ strategy can generate better code.
+
+[TARGET_LEGITIMIZE_ADDRESS]
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
+
+ This hook is used to undo the possibly obfuscating effects of the
+ ``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
+ macros. Some backend implementations of these macros wrap symbol
+ references inside an ``UNSPEC`` rtx to represent PIC or similar
+ addressing modes. This target hook allows GCC's optimizers to understand
+ the semantics of these opaque ``UNSPEC`` s by converting them back
+ into their original form.
+
+[TARGET_DELEGITIMIZE_ADDRESS]
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
+
+ This hook should return true if :samp:`{x}` should not be emitted into
+ debug sections.
+
+[TARGET_CONST_NOT_OK_FOR_DEBUG_P]
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
+
+ A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ Legitimate addresses are defined in two variants: a strict variant and a
+ non-strict one. The :samp:`{strict}` parameter chooses which variant is
+ desired by the caller.
+
+ The strict variant is used in the reload pass. It must be defined so
+ that any pseudo-register that has not been allocated a hard register is
+ considered a memory reference. This is because in contexts where some
+ kind of register is required, a pseudo-register with no hard register
+ must be rejected. For non-hard registers, the strict variant should look
+ up the ``reg_renumber`` array; it should then proceed using the hard
+ register number in the array, or treat the pseudo as a memory reference
+ if the array holds ``-1``.
+
+ The non-strict variant is used in other passes. It must be defined to
+ accept all pseudo-registers in every context where some kind of
+ register is required.
+
+ Normally, constant addresses which are the sum of a ``symbol_ref``
+ and an integer are stored inside a ``const`` RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any ``const`` as legitimate.
+
+ Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
+ sums that are not marked with ``const``. It assumes that a naked
+ ``plus`` indicates indexing. If so, then you *must* reject such
+ naked constant sums as illegitimate addresses, so that none of them will
+ be given to ``PRINT_OPERAND_ADDRESS``.
+
+ .. index:: TARGET_ENCODE_SECTION_INFO and address validation
+
+ On some machines, whether a symbolic address is legitimate depends on
+ the section that the address refers to. On these machines, define the
+ target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
+ into the ``symbol_ref``, and then check for it here. When you see a
+ ``const``, you will have to look inside it to find the
+ ``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
+
+ .. index:: GO_IF_LEGITIMATE_ADDRESS
+
+ Some ports are still using a deprecated legacy substitute for
+ this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
+ has this syntax:
+
+ .. code-block:: c++
+
+ #define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
+
+ and should ``goto label`` if the address :samp:`{x}` is a valid
+ address on the target machine for a memory operand of mode :samp:`{mode}`.
+
+ .. index:: REG_OK_STRICT
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro ``REG_OK_STRICT``. You should use an
+ ``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
+ that case and the non-strict variant otherwise.
+
+ Using the hook is usually simpler because it limits the number of
+ files that are recompiled when changes are made.
+
+[TARGET_LEGITIMATE_ADDRESS_P]
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
+
+ This hook should return true if pool entries for constant :samp:`{x}` can
+ be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
+ of :samp:`{x}`.
+
+ The default version returns false for all constants.
+
+[TARGET_USE_BLOCKS_FOR_CONSTANT_P]
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
+
+ This hook should return true if pool entries for :samp:`{decl}` should
+ be placed in an ``object_block`` structure.
+
+ The default version returns true for all decls.
+
+[TARGET_USE_BLOCKS_FOR_DECL_P]
+
+[TARGET_MIN_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
+
+ The minimum offset that should be applied to a section anchor.
+ On most targets, it should be the smallest offset that can be
+ applied to a base register while still giving a legitimate address
+ for every mode. The default value is 0.
+
+[TARGET_MIN_ANCHOR_OFFSET]
+
+[TARGET_MAX_ANCHOR_OFFSET]
+.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
+
+ Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
+ offset that should be applied to section anchors. The default
+ value is 0.
+
+[TARGET_MAX_ANCHOR_OFFSET]
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
+
+ Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
+ :samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
+ :samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
+
+ The default version is correct for most targets, but you might need to
+ intercept this hook to handle things like target-specific attributes
+ or target-specific sections.
+
+[TARGET_USE_ANCHORS_FOR_SYMBOL_P]
+
+[TARGET_HAS_IFUNC_P]
+.. function:: bool TARGET_HAS_IFUNC_P (void)
+
+ It returns true if the target supports GNU indirect functions.
+ The support includes the assembler, linker and dynamic linker.
+ The default value of this hook is based on target's libc.
+
+[TARGET_HAS_IFUNC_P]
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+.. function:: bool TARGET_IFUNC_REF_LOCAL_OK (void)
+
+ Return true if it is OK to reference indirect function resolvers
+ locally. The default is to return false.
+
+[TARGET_IFUNC_REF_LOCAL_OK]
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
+
+ True if it is OK to do sibling call optimization for the specified
+ call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
+ or ``NULL`` if this is an indirect call.
+
+ It is not uncommon for limitations of calling conventions to prevent
+ tail calls to functions outside the current unit of translation, or
+ during PIC compilation. The hook is used to enforce these restrictions,
+ as the ``sibcall`` md pattern cannot fail, or fall over to a
+ 'normal' call. The criteria for successful sibling call optimization
+ may vary greatly between different architectures.
+
+[TARGET_FUNCTION_OK_FOR_SIBCALL]
+
+[TARGET_SET_CURRENT_FUNCTION]
+.. function:: void TARGET_SET_CURRENT_FUNCTION (tree decl)
+
+ The compiler invokes this hook whenever it changes its current function
+ context (``cfun``). You can define this function if
+ the back end needs to perform any initialization or reset actions on a
+ per-function basis. For example, it may be used to implement function
+ attributes that affect register usage or code generation patterns.
+ The argument :samp:`{decl}` is the declaration for the new function context,
+ and may be null to indicate that the compiler has left a function context
+ and is returning to processing at the top level.
+ The default hook function does nothing.
+
+ GCC sets ``cfun`` to a dummy function context during initialization of
+ some parts of the back end. The hook function is not invoked in this
+ situation; you need not worry about the hook being invoked recursively,
+ or when the back end is in a partially-initialized state.
+ ``cfun`` might be ``NULL`` to indicate processing at top level,
+ outside of any function scope.
+
+[TARGET_SET_CURRENT_FUNCTION]
+
+[TARGET_IN_SMALL_DATA_P]
+.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` should be placed into a 'small data' section.
+ The default version of this hook always returns false.
+
+[TARGET_IN_SMALL_DATA_P]
+
+[TARGET_BINDS_LOCAL_P]
+.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
+
+ Returns true if :samp:`{exp}` names an object for which name resolution
+ rules must resolve to the current 'module' (dynamic shared library
+ or executable image).
+
+ The default version of this hook implements the name resolution rules
+ for ELF, which has a looser model of global name binding than other
+ currently supported object file formats.
+
+[TARGET_BINDS_LOCAL_P]
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
+
+ It returns true if target wants profile code emitted before prologue.
+
+ The default version of this hook use the target macro
+ ``PROFILE_BEFORE_PROLOGUE``.
+
+[TARGET_PROFILE_BEFORE_PROLOGUE]
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
+
+ This target hook returns true if the target wants the leaf flag for
+ the current function to stay true even if it calls mcount. This might
+ make sense for targets using the leaf flag only to determine whether a
+ stack frame needs to be generated or not and for which the call to
+ mcount is generated before the function prologue.
+
+[TARGET_KEEP_LEAF_WHEN_PROFILED]
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
+
+ Define this hook if you need to postprocess the assembler name generated
+ by target-independent code. The :samp:`{id}` provided to this hook will be
+ the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
+ or the mangled name of the :samp:`{decl}` in C++). The return value of the
+ hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
+ your target system. The default implementation of this hook just
+ returns the :samp:`{id}` provided.
+
+[TARGET_MANGLE_DECL_ASSEMBLER_NAME]
+
+[TARGET_ENCODE_SECTION_INFO]
+.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
+
+ Define this hook if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The hook is executed immediately after rtl has been created for
+ :samp:`{decl}`, which may be a variable or function declaration or
+ an entry in the constant pool. In either case, :samp:`{rtl}` is the
+ rtl in question. Do *not* use ``DECL_RTL (decl)``
+ in this hook; that field may not have been initialized yet.
+
+ In the case of a constant, it is safe to assume that the rtl is
+ a ``mem`` whose address is a ``symbol_ref``. Most decls
+ will also have this form, but that is not guaranteed. Global
+ register variables, for instance, will have a ``reg`` for their
+ rtl. (Normally the right thing to do with such unusual rtl is
+ leave it alone.)
+
+ The :samp:`{new_decl_p}` argument will be true if this is the first time
+ that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
+ be false for subsequent invocations, which will happen for duplicate
+ declarations. Whether or not anything must be done for the duplicate
+ declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
+ :samp:`{new_decl_p}` is always true when the hook is called for a constant.
+
+ .. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
+
+ The usual thing for this hook to do is to record flags in the
+ ``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
+ Historically, the name string was modified if it was necessary to
+ encode more than one bit of information, but this practice is now
+ discouraged; use ``SYMBOL_REF_FLAGS``.
+
+ The default definition of this hook, ``default_encode_section_info``
+ in :samp:`varasm.cc`, sets a number of commonly-useful bits in
+ ``SYMBOL_REF_FLAGS``. Check whether the default does what you need
+ before overriding it.
+
+[TARGET_ENCODE_SECTION_INFO]
+
+[TARGET_STRIP_NAME_ENCODING]
+.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
+
+ Decode :samp:`{name}` and return the real name part, sans
+ the characters that ``TARGET_ENCODE_SECTION_INFO``
+ may have added.
+
+[TARGET_STRIP_NAME_ENCODING]
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+.. function:: unsigned HOST_WIDE_INT TARGET_SHIFT_TRUNCATION_MASK (machine_mode mode)
+
+ This function describes how the standard shift patterns for :samp:`{mode}`
+ deal with shifts by negative amounts or by more than the width of the mode.
+ See :ref:`shift-patterns`.
+
+ On many machines, the shift patterns will apply a mask :samp:`{m}` to the
+ shift count, meaning that a fixed-width shift of :samp:`{x}` by :samp:`{y}` is
+ equivalent to an arbitrary-width shift of :samp:`{x}` by :samp:`{y & m}`. If
+ this is true for mode :samp:`{mode}`, the function should return :samp:`{m}`,
+ otherwise it should return 0. A return value of 0 indicates that no
+ particular behavior is guaranteed.
+
+ Note that, unlike ``SHIFT_COUNT_TRUNCATED``, this function does
+ *not* apply to general shift rtxes; it applies only to instructions
+ that are generated by the named shift patterns.
+
+ The default implementation of this function returns
+ ``GET_MODE_BITSIZE (mode) - 1`` if ``SHIFT_COUNT_TRUNCATED``
+ and 0 otherwise. This definition is always safe, but if
+ ``SHIFT_COUNT_TRUNCATED`` is false, and some shift patterns
+ nevertheless truncate the shift count, you may get better code
+ by overriding it.
+
+[TARGET_SHIFT_TRUNCATION_MASK]
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+.. function:: unsigned int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (machine_mode mode)
+
+ When :option:`-ffast-math` is in effect, GCC tries to optimize
+ divisions by the same divisor, by turning them into multiplications by
+ the reciprocal. This target hook specifies the minimum number of divisions
+ that should be there for GCC to perform the optimization for a variable
+ of mode :samp:`{mode}`. The default implementation returns 3 if the machine
+ has an instruction for the division, and 2 if it does not.
+
+[TARGET_MIN_DIVISIONS_FOR_RECIP_MUL]
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+.. function:: bool TARGET_TRULY_NOOP_TRUNCATION (poly_uint64 outprec, poly_uint64 inprec)
+
+ This hook returns true if it is safe to 'convert' a value of
+ :samp:`{inprec}` bits to one of :samp:`{outprec}` bits (where :samp:`{outprec}` is
+ smaller than :samp:`{inprec}`) by merely operating on it as if it had only
+ :samp:`{outprec}` bits. The default returns true unconditionally, which
+ is correct for most machines. When ``TARGET_TRULY_NOOP_TRUNCATION``
+ returns false, the machine description should provide a ``trunc``
+ optab to specify the RTL that performs the required truncation.
+
+ If ``TARGET_MODES_TIEABLE_P`` returns false for a pair of modes,
+ suboptimal code can result if this hook returns true for the corresponding
+ mode sizes. Making this hook return false in such cases may improve things.
+
+[TARGET_TRULY_NOOP_TRUNCATION]
+
+[TARGET_MODE_REP_EXTENDED]
+.. function:: int TARGET_MODE_REP_EXTENDED (scalar_int_mode mode, scalar_int_mode rep_mode)
+
+ The representation of an integral mode can be such that the values
+ are always extended to a wider integral mode. Return
+ ``SIGN_EXTEND`` if values of :samp:`{mode}` are represented in
+ sign-extended form to :samp:`{rep_mode}`. Return ``UNKNOWN``
+ otherwise. (Currently, none of the targets use zero-extended
+ representation this way so unlike ``LOAD_EXTEND_OP``,
+ ``TARGET_MODE_REP_EXTENDED`` is expected to return either
+ ``SIGN_EXTEND`` or ``UNKNOWN``. Also no target extends
+ :samp:`{mode}` to :samp:`{rep_mode}` so that :samp:`{rep_mode}` is not the next
+ widest integral mode and currently we take advantage of this fact.)
+
+ Similarly to ``LOAD_EXTEND_OP`` you may return a non- ``UNKNOWN``
+ value even if the extension is not performed on certain hard registers
+ as long as for the ``REGNO_REG_CLASS`` of these hard registers
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` returns false.
+
+ Note that ``TARGET_MODE_REP_EXTENDED`` and ``LOAD_EXTEND_OP``
+ describe two related properties. If you define
+ ``TARGET_MODE_REP_EXTENDED (mode, word_mode)`` you probably also want
+ to define ``LOAD_EXTEND_OP (mode)`` to return the same type of
+ extension.
+
+ In order to enforce the representation of ``mode``,
+ ``TARGET_TRULY_NOOP_TRUNCATION`` should return false when truncating to
+ ``mode``.
+
+[TARGET_MODE_REP_EXTENDED]
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+.. function:: bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+
+ On some targets, it is assumed that the compiler will spill all pseudos
+ that are live across a call to ``setjmp``, while other targets treat
+ ``setjmp`` calls as normal function calls.
+
+ This hook returns false if ``setjmp`` calls do not preserve all
+ non-volatile registers so that gcc that must spill all pseudos that are
+ live across ``setjmp`` calls. Define this to return true if the
+ target does not need to spill all pseudos live across ``setjmp`` calls.
+ The default implementation conservatively assumes all pseudos must be
+ spilled across ``setjmp`` calls.
+
+[TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P]
+
+[TARGET_VALID_POINTER_MODE]
+.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}`. The default version of this
+ hook returns true for both ``ptr_mode`` and ``Pmode``.
+
+[TARGET_VALID_POINTER_MODE]
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
+
+ Define this to return nonzero if the memory reference :samp:`{ref}`
+ may alias with the system C library errno location. The default
+ version of this hook assumes the system C library errno location
+ is either a declaration of type int or accessed by dereferencing
+ a pointer to int.
+
+[TARGET_REF_MAY_ALIAS_ERRNO]
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for pointers to
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``ptr_mode``.
+
+[TARGET_ADDR_SPACE_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
+
+ Define this to return the machine mode to use for addresses in
+ :samp:`{address_space}` if the target supports named address spaces.
+ The default version of this hook returns ``Pmode``.
+
+[TARGET_ADDR_SPACE_ADDRESS_MODE]
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
+
+ Define this to return nonzero if the port can handle pointers
+ with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
+ except that it includes explicit named address space support. The default
+ version of this hook returns true for the modes returned by either the
+ ``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
+ target hooks for the given address space.
+
+[TARGET_ADDR_SPACE_VALID_POINTER_MODE]
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
+
+ Define this to return true if :samp:`{exp}` is a valid address for mode
+ :samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
+ parameter says whether strict addressing is in effect after reload has
+ finished. This target hook is the same as the
+ ``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
+ explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
+
+ Define this to modify an invalid address :samp:`{x}` to be a valid address
+ with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
+ hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
+ except that it includes explicit named address space support.
+
+[TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
+
+ Define this to return whether the :samp:`{subset}` named address space is
+ contained within the :samp:`{superset}` named address space. Pointers to
+ a named address space that is a subset of another named address space
+ will be converted automatically without a cast if used together in
+ arithmetic operations. Pointers to a superset address space can be
+ converted to pointers to a subset address space via explicit casts.
+
+[TARGET_ADDR_SPACE_SUBSET_P]
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
+
+ Define this to modify the default handling of address 0 for the
+ address space. Return true if 0 should be considered a valid address.
+
+[TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
+
+[TARGET_ADDR_SPACE_CONVERT]
+.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
+
+ Define this to convert the pointer expression represented by the RTL
+ :samp:`{op}` with type :samp:`{from_type}` that points to a named address
+ space to a new pointer expression with type :samp:`{to_type}` that points
+ to a different named address space. When this hook it called, it is
+ guaranteed that one of the two address spaces is a subset of the other,
+ as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
+
+[TARGET_ADDR_SPACE_CONVERT]
+
+[TARGET_ADDR_SPACE_DEBUG]
+.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
+
+ Define this to define how the address space is encoded in dwarf.
+ The result is the value to be used with ``DW_AT_address_class``.
+
+[TARGET_ADDR_SPACE_DEBUG]
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
+
+ Define this hook if the availability of an address space depends on
+ command line options and some diagnostics should be printed when the
+ address space is used. This hook is called during parsing and allows
+ to emit a better diagnostic compared to the case where the address space
+ was not registered with ``c_register_addr_space``. :samp:`{as}` is
+ the address space as registered with ``c_register_addr_space``.
+ :samp:`{loc}` is the location of the address space qualifier token.
+ The default implementation does nothing.
+
+[TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
+
+ Define this hook to lower alignment of local, parm or result
+ decl :samp:`({decl})`.
+
+[TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
+
+ This hook returns the preferred alignment in bits for a
+ statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
+ is the mode of the rtx. The default implementation returns
+ :samp:`GET_MODE_ALIGNMENT ({mode})`.
+
+[TARGET_STATIC_RTX_ALIGNMENT]
+
+[TARGET_CONSTANT_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
+
+ This hook returns the alignment in bits of a constant that is being
+ placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
+ is the alignment that the object would ordinarily have.
+
+ The default definition just returns :samp:`{basic_align}`.
+
+ The typical use of this hook is to increase alignment for string
+ constants to be word aligned so that ``strcpy`` calls that copy
+ constants can be done inline. The function
+ ``constant_alignment_word_strings`` provides such a definition.
+
+[TARGET_CONSTANT_ALIGNMENT]
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
+
+ Define this hook if during mode attribute processing, the port should
+ translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
+ ``KFmode``, when it is the same as ``TFmode``.
+
+ The default version of the hook returns that mode that was passed in.
+
+[TARGET_TRANSLATE_MODE_ATTRIBUTE]
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
+ considered supported, all the basic arithmetic and comparisons
+ must work.
+
+ The default version of this hook returns true for any mode
+ required to handle the basic C types (as defined by the port).
+ Included here are the double-word arithmetic supported by the
+ code in :samp:`optabs.cc`.
+
+[TARGET_SCALAR_MODE_SUPPORTED_P]
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
+
+ Define this to return nonzero if the port is prepared to handle
+ insns involving vector mode :samp:`{mode}`. At the very least, it
+ must have move patterns for this mode.
+
+[TARGET_VECTOR_MODE_SUPPORTED_P]
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
+
+ Return true if there is no target-specific reason for treating
+ vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
+ has already checked for target-independent reasons, meaning that the
+ types are known to have the same mode, to have the same number of elements,
+ and to have what the caller considers to be compatible element types.
+
+ The main reason for defining this hook is to reject pairs of types
+ that are handled differently by the target's calling convention.
+ For example, when a new :samp:`{N}` -bit vector architecture is added
+ to a target, the target may want to handle normal :samp:`{N}` -bit
+ ``VECTOR_TYPE`` arguments and return values in the same way as
+ before, to maintain backwards compatibility. However, it may also
+ provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
+ and returned in a more efficient way. It is then important to maintain
+ a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
+ architecture-specific ones.
+
+ The default implementation returns true, which is correct for most targets.
+
+[TARGET_COMPATIBLE_VECTOR_TYPES_P]
+
+[TARGET_VECTOR_ALIGNMENT]
+.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
+
+ This hook can be used to define the alignment for a vector of type
+ :samp:`{type}`, in order to comply with a platform ABI. The default is to
+ require natural alignment for vector types. The alignment returned by
+ this hook must be a power-of-two multiple of the default alignment of
+ the vector element type.
+
+[TARGET_VECTOR_ALIGNMENT]
+
+[TARGET_ARRAY_MODE]
+.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return the mode that GCC should use for an array that has
+ :samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
+ Return no mode if the target has no special requirements. In the
+ latter case, GCC looks for an integer mode of the appropriate size
+ if available and uses BLKmode otherwise. Usually the search for the
+ integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
+ ``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
+ used in specific cases.
+
+ The main use of this hook is to specify that an array of vectors should
+ also have a vector mode. The default implementation returns no mode.
+
+[TARGET_ARRAY_MODE]
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
+
+ Return true if GCC should try to use a scalar mode to store an array
+ of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
+ Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
+ and allows GCC to use any defined integer mode.
+
+ One use of this hook is to support vector load and store operations
+ that operate on several homogeneous vectors. For example, ARM NEON
+ has operations like:
+
+ .. code-block:: c++
+
+ int8x8x3_t vld3_s8 (const int8_t *)
+
+ where the return type is defined as:
+
+ .. code-block:: c++
+
+ typedef struct int8x8x3_t
+ {
+ int8x8_t val[3];
+ } int8x8x3_t;
+
+ If this hook allows ``val`` to have a scalar mode, then
+ ``int8x8x3_t`` can have the same mode. GCC can then store
+ ``int8x8x3_t`` s in registers rather than forcing them onto the stack.
+
+[TARGET_ARRAY_MODE_SUPPORTED_P]
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
+
+ Define this to return nonzero if libgcc provides support for the
+ floating-point mode :samp:`{mode}`, which is known to pass
+ ``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
+ hook returns true for all of ``SFmode``, ``DFmode``,
+ ``XFmode`` and ``TFmode``, if such modes exist.
+
+[TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
+
+[TARGET_FLOATN_MODE]
+.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
+
+ Define this to return the machine mode to use for the type
+ ``_Floatn``, if :samp:`{extended}` is false, or the type
+ ``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
+ supported, return ``opt_scalar_float_mode ()``. The default version of
+ this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
+ ``_Float64`` and ``_Float32x`` and ``TFmode`` for
+ ``_Float128``, if those modes exist and satisfy the requirements for
+ those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
+ ``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
+ returns the first of ``XFmode`` and ``TFmode`` that exists and
+ satisfies the same requirements; for other types, it returns
+ ``opt_scalar_float_mode ()``. The hook is only called for values
+ of :samp:`{n}` and :samp:`{extended}` that are valid according to
+ ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
+ if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
+
+[TARGET_FLOATN_MODE]
+
+[TARGET_FLOATN_BUILTIN_P]
+.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
+
+ Define this to return true if the ``_Floatn`` and
+ ``_Floatnx`` built-in functions should implicitly enable the
+ built-in function without the ``__builtin_`` prefix in addition to the
+ normal built-in function with the ``__builtin_`` prefix. The default is
+ to only enable built-in functions without the ``__builtin_`` prefix for
+ the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
+ the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
+ ``enum built_in_function`` id of the function to be enabled.
+
+[TARGET_FLOATN_BUILTIN_P]
+
+[TARGET_REGISTER_MOVE_COST]
+.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
+ are expressed using the enumeration values such as ``GENERAL_REGS``.
+ A value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when :samp:`{from}` is the
+ same as :samp:`{to}` ; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single ``set`` between two
+ hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
+ classes returns a value of 2, reload does not check to ensure that the
+ constraints of the insn are met. Setting a cost of other than 2 will
+ allow reload to verify that the constraints are met. You should do this
+ if the :samp:`mov{m}` pattern's constraints do not allow such copying.
+
+ The default version of this function returns 2.
+
+[TARGET_REGISTER_MOVE_COST]
+
+[TARGET_MEMORY_MOVE_COST]
+.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
+
+ This target hook should return the cost of moving data of mode :samp:`{mode}`
+ between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
+ if the value is to be written to memory, ``true`` if it is to be read in.
+ This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
+ If moving between registers and memory is more expensive than between two
+ registers, you should add this target hook to express the relative cost.
+
+ If you do not add this target hook, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to copy
+ between memory and a register of :samp:`{rclass}` but the reload mechanism is
+ more complex than copying via an intermediate, use this target hook to
+ reflect the actual cost of the move.
+
+ GCC defines the function ``memory_move_secondary_cost`` if
+ secondary reloads are needed. It computes the costs due to copying via
+ a secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base value of
+ 4 is not correct for your machine, use this target hook to add some other
+ value to the result of that function. The arguments to that function
+ are the same as to this target hook.
+
+[TARGET_MEMORY_MOVE_COST]
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
+
+ GCC will attempt several strategies when asked to copy between
+ two areas of memory, or to set, clear or store to memory, for example
+ when copying a ``struct``. The ``by_pieces`` infrastructure
+ implements such memory operations as a sequence of load, store or move
+ insns. Alternate strategies are to expand the
+ ``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
+ unit-by-unit, loop-based operations.
+
+ This target hook should return true if, for a memory operation with a
+ given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
+ infrastructure is expected to result in better code generation.
+ Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
+ units.
+
+ The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
+ ``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
+ ``COMPARE_BY_PIECES``. These describe the type of memory operation
+ under consideration.
+
+ The parameter :samp:`{speed_p}` is true if the code is currently being
+ optimized for speed rather than size.
+
+ Returning true for higher values of :samp:`{size}` can improve code generation
+ for speed if the target does not provide an implementation of the
+ ``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
+ ``setmem`` implementation would be more expensive than a sequence of
+ insns, or if the overhead of a library call would dominate that of
+ the body of the memory operation.
+
+ Returning true for higher values of ``size`` may also cause an increase
+ in code size, for example where the number of insns emitted to perform a
+ move would be greater than that of a library call.
+
+[TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
+
+ This target hook should return true if when the ``by_pieces``
+ infrastructure is used, an offset adjusted unaligned memory operation
+ in the smallest integer mode for the last piece operation of a memory
+ region can be generated to avoid doing more than one smaller operations.
+
+[TARGET_OVERLAP_OP_BY_PIECES_P]
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
+
+ When expanding a block comparison in MODE, gcc can try to reduce the
+ number of branches at the expense of more memory operations. This hook
+ allows the target to override the default choice. It should return the
+ factor by which branches should be reduced over the plain expansion with
+ one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
+ particular mode from being used for block comparisons by returning a
+ negative number from this hook.
+
+[TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
+
+ This hook returns true if memory accesses described by the
+ :samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap handler.
+ This hook is invoked only for unaligned accesses, i.e. when
+ ``alignment < GET_MODE_ALIGNMENT (mode)``.
+
+ When this hook returns true, the compiler will act as if
+ ``STRICT_ALIGNMENT`` were true when generating code for block
+ moves. This can cause significantly more instructions to be produced.
+ Therefore, do not make this hook return true if unaligned accesses only
+ add a cycle or two to the time for a memory access.
+
+ The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
+ The default implementation returns ``STRICT_ALIGNMENT``.
+
+[TARGET_SLOW_UNALIGNED_ACCESS]
+
+[TARGET_OPTAB_SUPPORTED_P]
+.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
+
+ Return true if the optimizers should use optab :samp:`{op}` with
+ modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
+ The optab is known to have an associated :samp:`.md` instruction
+ whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
+ optabs; for direct optabs it is a copy of :samp:`{mode1}`.
+
+ For example, when called with :samp:`{op}` equal to ``rint_optab`` and
+ :samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
+ optimizers should use optab ``rintdf2``.
+
+ The default hook returns true for all inputs.
+
+[TARGET_OPTAB_SUPPORTED_P]
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
+
+ Define this to return nonzero for machine modes for which the port has
+ small register classes. If this target hook returns nonzero for a given
+ :samp:`{mode}`, the compiler will try to minimize the lifetime of registers
+ in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
+ In this case, the hook is expected to return nonzero if it returns nonzero
+ for any mode.
+
+ On some machines, it is risky to let hard registers live across arbitrary
+ insns. Typically, these machines have instructions that require values
+ to be in specific registers (like an accumulator), and reload will fail
+ if the required hard register is used for another purpose across such an
+ insn.
+
+ Passes before reload do not know which hard registers will be used
+ in an instruction, but the machine modes of the registers set or used in
+ the instruction are already known. And for some machines, register
+ classes are small for, say, integer registers but not for floating point
+ registers. For example, the AMD x86-64 architecture requires specific
+ registers for the legacy x86 integer instructions, but there are many
+ SSE registers for floating point operations. On such targets, a good
+ strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
+ machine modes but zero for the SSE register classes.
+
+ The default version of this hook returns false for any mode. It is always
+ safe to redefine this hook to return with a nonzero value. But if you
+ unnecessarily define it, you will reduce the amount of optimizations
+ that can be performed in some cases. If you do not define this hook
+ to return a nonzero value when it is required, the compiler will run out
+ of spill registers and print a fatal error message.
+
+[TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
+
+[TARGET_FLAGS_REGNUM]
+.. c:var:: unsigned int TARGET_FLAGS_REGNUM
+
+ If the target has a dedicated flags register, and it needs to use the
+ post-reload comparison elimination pass, or the delay slot filler pass,
+ then this value should be set appropriately.
+
+[TARGET_FLAGS_REGNUM]
+
+[TARGET_RTX_COSTS]
+.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
+
+ This target hook describes the relative costs of RTL expressions.
+
+ The cost may depend on the precise form of the expression, which is
+ available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
+ as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
+ That is, the hook can assume that there is some rtx :samp:`{y}` such
+ that :samp:`GET_CODE ({y}) == {outer_code}` and such that
+ either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
+ (b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
+
+ :samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
+ do not have a mode, the mode in which :samp:`{x}` is used.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ On entry to the hook, ``*total`` contains a default estimate
+ for the cost of the expression. The hook should modify this value as
+ necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
+ for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
+ operations, and ``COSTS_N_INSNS (1)`` for all other operations.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+ The hook returns true when all subexpressions of :samp:`{x}` have been
+ processed, and false when ``rtx_cost`` should recurse.
+
+[TARGET_RTX_COSTS]
+
+[TARGET_ADDRESS_COST]
+.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
+
+ This hook computes the cost of an addressing mode that contains
+ :samp:`{address}`. If not defined, the cost is computed from
+ the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
+
+ For most CISC machines, the default cost is a good approximation of the
+ true cost of the addressing mode. However, on RISC machines, all
+ instructions normally have the same length and execution time. Hence
+ all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form with
+ the lowest cost will be used. If multiple forms have the same, lowest,
+ cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a register
+ and a constant is used twice in the same basic block. When this macro
+ is not defined, the address will be computed in a register and memory
+ references will be indirect through that register. On machines where
+ the cost of the addressing mode containing the sum is no higher than
+ that of a simple indirect reference, this will produce an additional
+ instruction and possibly require an additional register. Proper
+ specification of this macro eliminates this overhead for such machines.
+
+ This hook is never called with an invalid address.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register, defining
+ ``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ ``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
+ should be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers of
+ registers on machines with lots of registers.
+
+[TARGET_ADDRESS_COST]
+
+[TARGET_INSN_COST]
+.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
+
+ This target hook describes the relative costs of RTL instructions.
+
+ In implementing this hook, you can use the construct
+ ``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
+ instructions.
+
+ When optimizing for code size, i.e. when ``speed`` is
+ false, this target hook should be used to estimate the relative
+ size cost of an expression, again relative to ``COSTS_N_INSNS``.
+
+[TARGET_INSN_COST]
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
+
+ This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
+ giving the maximum acceptable cost for a sequence generated by the RTL
+ if-conversion pass when conditional execution is not available.
+ The RTL if-conversion pass attempts to convert conditional operations
+ that would require a branch to a series of unconditional operations and
+ ``movmodecc`` insns. This hook returns the maximum cost of the
+ unconditional instructions and the ``movmodecc`` insns.
+ RTL if-conversion is cancelled if the cost of the converted sequence
+ is greater than the value returned by this hook.
+
+ ``e`` is the edge between the basic block containing the conditional
+ branch to the basic block which would be executed if the condition
+ were true.
+
+ The default implementation of this hook uses the
+ ``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
+ and uses a multiple of ``BRANCH_COST`` otherwise.
+
+[TARGET_MAX_NOCE_IFCVT_SEQ_COST]
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
+
+ This hook returns true if the instruction sequence ``seq`` is a good
+ candidate as a replacement for the if-convertible sequence described in
+ ``if_info``.
+
+[TARGET_NOCE_CONVERSION_PROFITABLE_P]
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
+
+ Return ``true`` if it is profitable to replace the address in
+ :samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
+ scheduler from undoing address optimizations. The instruction containing the
+ memref is :samp:`{insn}`. The default implementation returns ``true``.
+
+[TARGET_NEW_ADDRESS_PROFITABLE_P]
+
+[TARGET_ESTIMATED_POLY_VALUE]
+.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
+
+ Return an estimate of the runtime value of :samp:`{val}`, for use in
+ things like cost calculations or profiling frequencies. :samp:`{kind}` is used
+ to ask for the minimum, maximum, and likely estimates of the value through
+ the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
+ ``POLY_VALUE_LIKELY`` values. The default
+ implementation returns the lowest possible value of :samp:`{val}`.
+
+[TARGET_ESTIMATED_POLY_VALUE]
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
+
+ This predicate controls the use of the eager delay slot filler to disallow
+ speculatively executed instructions being placed in delay slots. Targets
+ such as certain MIPS architectures possess both branches with and without
+ delay slots. As the eager delay slot filler can decrease performance,
+ disabling it is beneficial when ordinary branches are available. Use of
+ delay slot branches filled using the basic filler is often still desirable
+ as the delay slot can hide a pipeline bubble.
+
+[TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+.. function:: rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx hard_reg)
+
+ When the initial value of a hard register has been copied in a pseudo
+ register, it is often not necessary to actually allocate another register
+ to this pseudo register, because the original hard register or a stack slot
+ it has been saved into can be used. ``TARGET_ALLOCATE_INITIAL_VALUE``
+ is called at the start of register allocation once for each hard register
+ that had its initial value copied by using
+ ``get_func_hard_reg_initial_val`` or ``get_hard_reg_initial_val``.
+ Possible values are ``NULL_RTX``, if you don't want
+ to do any special allocation, a ``REG`` rtx---that would typically be
+ the hard register itself, if it is known not to be clobbered---or a
+ ``MEM``.
+ If you are returning a ``MEM``, this is only a hint for the allocator;
+ it might decide to use another register anyways.
+ You may use ``current_function_is_leaf`` or
+ ``REG_N_SETS`` in the hook to determine if the hard
+ register in question will not be clobbered.
+ The default value of this hook is ``NULL``, which disables any special
+ allocation.
+
+[TARGET_ALLOCATE_INITIAL_VALUE]
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+.. function:: int TARGET_UNSPEC_MAY_TRAP_P (const_rtx x, unsigned flags)
+
+ This target hook returns nonzero if :samp:`{x}`, an ``unspec`` or
+ ``unspec_volatile`` operation, might cause a trap. Targets can use
+ this hook to enhance precision of analysis for ``unspec`` and
+ ``unspec_volatile`` operations. You may call ``may_trap_p_1``
+ to analyze inner elements of :samp:`{x}` in which case :samp:`{flags}` should be
+ passed along.
+
+[TARGET_UNSPEC_MAY_TRAP_P]
+
+[TARGET_DWARF_REGISTER_SPAN]
+.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
+
+ Given a register, this hook should return a parallel of registers to
+ represent where to find the register pieces. Define this hook if the
+ register and its mode are represented in Dwarf in non-contiguous
+ locations, or if the register should be represented in more than one
+ register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
+ If not defined, the default is to return ``NULL_RTX``.
+
+[TARGET_DWARF_REGISTER_SPAN]
+
+[TARGET_DWARF_FRAME_REG_MODE]
+.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
+
+ Given a register, this hook should return the mode which the
+ corresponding Dwarf frame register should have. This is normally
+ used to return a smaller mode than the raw mode to prevent call
+ clobbered parts of a register altering the frame register size
+
+[TARGET_DWARF_FRAME_REG_MODE]
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
+
+ If some registers are represented in Dwarf-2 unwind information in
+ multiple pieces, define this hook to fill in information about the
+ sizes of those pieces in the table used by the unwinder at runtime.
+ It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
+ filling in a single size corresponding to each hard register;
+ :samp:`{address}` is the address of the table.
+
+[TARGET_INIT_DWARF_REG_SIZES_EXTRA]
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
+
+ On targets which use a hard
+ register rather than a pseudo-register to hold condition codes, the
+ regular CSE passes are often not able to identify cases in which the
+ hard register is set to a common value. Use this hook to enable a
+ small pass which optimizes such cases. This hook should return true
+ to enable this pass, and it should set the integers to which its
+ arguments point to the hard register numbers used for condition codes.
+ When there is only one such register, as is true on most systems, the
+ integer pointed to by :samp:`{p2}` should be set to
+ ``INVALID_REGNUM``.
+
+ The default version of this hook returns false.
+
+[TARGET_FIXED_CONDITION_CODE_REGS]
+
+[TARGET_CC_MODES_COMPATIBLE]
+.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
+
+ On targets which use multiple condition code modes in class
+ ``MODE_CC``, it is sometimes the case that a comparison can be
+ validly done in more than one mode. On such a system, define this
+ target hook to take two mode arguments and to return a mode in which
+ both comparisons may be validly done. If there is no such mode,
+ return ``VOIDmode``.
+
+ The default version of this hook checks whether the modes are the
+ same. If they are, it returns that mode. If they are different, it
+ returns ``VOIDmode``.
+
+[TARGET_CC_MODES_COMPATIBLE]
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+.. function:: void TARGET_MACHINE_DEPENDENT_REORG (void)
+
+ If non-null, this hook performs a target-specific pass over the
+ instruction stream. The compiler will run it at all optimization levels,
+ just before the point at which it normally does delayed-branch scheduling.
+
+ The exact purpose of the hook varies from target to target. Some use
+ it to do transformations that are necessary for correctness, such as
+ laying out in-function constant pools or avoiding hardware hazards.
+ Others use it as an opportunity to do some machine-dependent optimizations.
+
+ You need not implement the hook if it has nothing to do. The default
+ definition is null.
+
+[TARGET_MACHINE_DEPENDENT_REORG]
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
+
+ This hook returns a type node for ``va_list`` for the target.
+ The default version of the hook returns ``void*``.
+
+[TARGET_BUILD_BUILTIN_VA_LIST]
+
+[TARGET_ENUM_VA_LIST_P]
+.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
+
+ This target hook is used in function ``c_common_nodes_and_builtins``
+ to iterate through the target specific builtin types for va_list. The
+ variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
+ to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
+ variable.
+ The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
+ this macro and are set to the name of the va_list builtin type and its
+ internal type.
+ If the return value of this macro is zero, then there is no more element.
+ Otherwise the :samp:`{IDX}` should be increased for the next call of this
+ macro to iterate through all types.
+
+[TARGET_ENUM_VA_LIST_P]
+
+[TARGET_FN_ABI_VA_LIST]
+.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
+
+ This hook returns the va_list type of the calling convention specified by
+ :samp:`{fndecl}`.
+ The default version of this hook returns ``va_list_type_node``.
+
+[TARGET_FN_ABI_VA_LIST]
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
+
+ This hook returns the va_list type of the calling convention specified by the
+ type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
+ ``NULL_TREE``.
+
+[TARGET_CANONICAL_VA_LIST_TYPE]
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
+
+ This hook performs target-specific gimplification of
+ ``VA_ARG_EXPR``. The first two parameters correspond to the
+ arguments to ``va_arg`` ; the latter two are as in
+ ``gimplify.cc:gimplify_expr``.
+
+[TARGET_GIMPLIFY_VA_ARG_EXPR]
+
+[TARGET_GET_PCH_VALIDITY]
+.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
+
+ This hook returns a pointer to the data needed by
+ ``TARGET_PCH_VALID_P`` and sets
+ :samp:`*{sz}` to the size of the data in bytes.
+
+[TARGET_GET_PCH_VALIDITY]
+
+[TARGET_PCH_VALID_P]
+.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
+
+ This hook checks whether the options used to create a PCH file are
+ compatible with the current settings. It returns ``NULL``
+ if so and a suitable error message if not. Error messages will
+ be presented to the user and must be localized using :samp:`_({msg})`.
+
+ :samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
+ when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
+ It's safe to assume that the data was created by the same version of the
+ compiler, so no format checking is needed.
+
+ The default definition of ``default_pch_valid_p`` should be
+ suitable for most targets.
+
+[TARGET_PCH_VALID_P]
+
+[TARGET_PREPARE_PCH_SAVE]
+.. function:: void TARGET_PREPARE_PCH_SAVE (void)
+
+ Called before writing out a PCH file. If the target has some
+ garbage-collected data that needs to be in a particular state on PCH loads,
+ it can use this hook to enforce that state. Very few targets need
+ to do anything here.
+
+[TARGET_PREPARE_PCH_SAVE]
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
+
+ If this hook is nonnull, the default implementation of
+ ``TARGET_PCH_VALID_P`` will use it to check for compatible values
+ of ``target_flags``. :samp:`{pch_flags}` specifies the value that
+ ``target_flags`` had when the PCH file was created. The return
+ value is the same as for ``TARGET_PCH_VALID_P``.
+
+[TARGET_CHECK_PCH_TARGET_FLAGS]
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
+
+ This target hook should return true if the compiler should give an
+ ``enum`` type only as many bytes as it takes to represent the range
+ of possible values of that type. It should return false if all
+ ``enum`` types should be allocated like ``int``.
+
+ The default is to return false.
+
+[TARGET_DEFAULT_SHORT_ENUMS]
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
+
+ This target hook should return an rtx that is used to store
+ the address of the current frame into the built in ``setjmp`` buffer.
+ The default value, ``virtual_stack_vars_rtx``, is correct for most
+ machines. One reason you may need to define this target hook is if
+ ``hard_frame_pointer_rtx`` is the appropriate value on your machine.
+
+[TARGET_BUILTIN_SETJMP_FRAME_VALUE]
+
+[TARGET_MD_ASM_ADJUST]
+.. function:: rtx_insn * TARGET_MD_ASM_ADJUST (vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes, vec<const char *>& constraints, vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs, location_t loc)
+
+ This target hook may add :dfn:`clobbers` to :samp:`{clobbers}` and
+ :samp:`{clobbered_regs}` for any hard regs the port wishes to automatically
+ clobber for an asm. The :samp:`{outputs}` and :samp:`{inputs}` may be inspected
+ to avoid clobbering a register that is already used by the asm. :samp:`{loc}`
+ is the source location of the asm.
+
+ It may modify the :samp:`{outputs}`, :samp:`{inputs}`, :samp:`{input_modes}`, and
+ :samp:`{constraints}` as necessary for other pre-processing. In this case the
+ return value is a sequence of insns to emit after the asm. Note that
+ changes to :samp:`{inputs}` must be accompanied by the corresponding changes
+ to :samp:`{input_modes}`.
+
+[TARGET_MD_ASM_ADJUST]
+
+[TARGET_DWARF_CALLING_CONVENTION]
+.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
+
+ Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
+ be emitted for each function. Instead of an integer return the enum
+ value for the ``DW_CC_`` tag.
+
+[TARGET_DWARF_CALLING_CONVENTION]
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
+
+ This target hook allows the backend to emit frame-related insns that
+ contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
+ info engine will invoke it on insns of the form
+
+ .. code-block:: c++
+
+ (set (reg) (unspec [...] UNSPEC_INDEX))
+
+ and
+
+ .. code-block:: c++
+
+ (set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
+
+ to let the backend emit the call frame instructions. :samp:`{label}` is
+ the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
+ the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
+
+[TARGET_DWARF_HANDLE_FRAME_UNSPEC]
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
+
+ Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
+ expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
+ register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
+ that the value of the indeterminate is:
+
+ .. code-block:: c++
+
+ value_of(R) / factor - offset
+
+ A target only needs to define this hook if it sets
+ :samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
+
+[TARGET_DWARF_POLY_INDETERMINATE_VALUE]
+
+[TARGET_STACK_PROTECT_GUARD]
+.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
+
+ This hook returns a ``DECL`` node for the external variable to use
+ for the stack protection guard. This variable is initialized by the
+ runtime to some random value and is used to initialize the guard value
+ that is placed at the top of the local stack frame. The type of this
+ variable must be ``ptr_type_node``.
+
+ The default version of this hook creates a variable called
+ :samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_GUARD]
+
+[TARGET_STACK_PROTECT_FAIL]
+.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
+
+ This hook returns a ``CALL_EXPR`` that alerts the runtime that the
+ stack protect guard variable has been modified. This expression should
+ involve a call to a ``noreturn`` function.
+
+ The default version of this hook invokes a function called
+ :samp:`__stack_chk_fail`, taking no arguments. This function is
+ normally defined in :samp:`libgcc2.c`.
+
+[TARGET_STACK_PROTECT_FAIL]
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
+
+ Returns true if the target wants GCC's default stack protect runtime support,
+ otherwise return false. The default implementation always returns true.
+
+[TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+.. function:: bool TARGET_HAVE_SPECULATION_SAFE_VALUE (bool active)
+
+ This hook is used to determine the level of target support for
+ ``__builtin_speculation_safe_value``. If called with an argument
+ of false, it returns true if the target has been modified to support
+ this builtin. If called with an argument of true, it returns true
+ if the target requires active mitigation execution might be speculative.
+
+ The default implementation returns false if the target does not define
+ a pattern named ``speculation_barrier``. Else it returns true
+ for the first case and whether the pattern is enabled for the current
+ compilation for the second case.
+
+ For targets that have no processors that can execute instructions
+ speculatively an alternative implemenation of this hook is available:
+ simply redefine this hook to ``speculation_safe_value_not_needed``
+ along with your other target hooks.
+
+[TARGET_HAVE_SPECULATION_SAFE_VALUE]
+
+[TARGET_SPECULATION_SAFE_VALUE]
+.. function:: rtx TARGET_SPECULATION_SAFE_VALUE (machine_mode mode, rtx result, rtx val, rtx failval)
+
+ This target hook can be used to generate a target-specific code
+ sequence that implements the ``__builtin_speculation_safe_value``
+ built-in function. The function must always return :samp:`{val}` in
+ :samp:`{result}` in mode :samp:`{mode}` when the cpu is not executing
+ speculatively, but must never return that when speculating until it
+ is known that the speculation will not be unwound. The hook supports
+ two primary mechanisms for implementing the requirements. The first
+ is to emit a speculation barrier which forces the processor to wait
+ until all prior speculative operations have been resolved; the second
+ is to use a target-specific mechanism that can track the speculation
+ state and to return :samp:`{failval}` if it can determine that
+ speculation must be unwound at a later time.
+
+ The default implementation simply copies :samp:`{val}` to :samp:`{result}` and
+ emits a ``speculation_barrier`` instruction if that is defined.
+
+[TARGET_SPECULATION_SAFE_VALUE]
+
+[TARGET_PREDICT_DOLOOP_P]
+.. function:: bool TARGET_PREDICT_DOLOOP_P (class loop *loop)
+
+ Return true if we can predict it is possible to use a low-overhead loop
+ for a particular loop. The parameter :samp:`{loop}` is a pointer to the loop.
+ This target hook is required only when the target supports low-overhead
+ loops, and will help ivopts to make some decisions.
+ The default version of this hook returns false.
+
+[TARGET_PREDICT_DOLOOP_P]
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+.. c:var:: bool TARGET_HAVE_COUNT_REG_DECR_P
+
+ Return true if the target supports hardware count register for decrement
+ and branch.
+ The default value is false.
+
+[TARGET_HAVE_COUNT_REG_DECR_P]
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_GENERIC
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any generic IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for generic IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this especially for generic IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_GENERIC]
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+.. c:var:: int64_t TARGET_DOLOOP_COST_FOR_ADDRESS
+
+ One IV candidate dedicated for doloop is introduced in IVOPTs, we can
+ calculate the computation cost of adopting it to any address IV use by
+ function get_computation_cost as before. But for targets which have
+ hardware count register support for decrement and branch, it may have to
+ move IV value from hardware count register to general purpose register
+ while doloop IV candidate is used for address IV uses. It probably takes
+ expensive penalty. This hook allows target owners to define the cost for
+ this escpecially for address IV uses.
+ The default value is zero.
+
+[TARGET_DOLOOP_COST_FOR_ADDRESS]
+
+[TARGET_CAN_USE_DOLOOP_P]
+.. function:: bool TARGET_CAN_USE_DOLOOP_P (const widest_int &iterations, const widest_int &iterations_max, unsigned int loop_depth, bool entered_at_top)
+
+ Return true if it is possible to use low-overhead loops (``doloop_end``
+ and ``doloop_begin``) for a particular loop. :samp:`{iterations}` gives the
+ exact number of iterations, or 0 if not known. :samp:`{iterations_max}` gives
+ the maximum number of iterations, or 0 if not known. :samp:`{loop_depth}` is
+ the nesting depth of the loop, with 1 for innermost loops, 2 for loops that
+ contain innermost loops, and so on. :samp:`{entered_at_top}` is true if the
+ loop is only entered from the top.
+
+ This hook is only used if ``doloop_end`` is available. The default
+ implementation returns true. You can use ``can_use_doloop_if_innermost``
+ if the loop must be the innermost, and if there are no other restrictions.
+
+[TARGET_CAN_USE_DOLOOP_P]
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+.. function:: const char * TARGET_INVALID_WITHIN_DOLOOP (const rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return NULL if it is valid within a
+ low-overhead loop, otherwise return a string explaining why doloop
+ could not be applied.
+
+ Many targets use special registers for low-overhead looping. For any
+ instruction that clobbers these this function should return a string indicating
+ the reason why the doloop could not be applied.
+ By default, the RTL loop optimizer does not use a present doloop pattern for
+ loops containing function calls or branch on table instructions.
+
+[TARGET_INVALID_WITHIN_DOLOOP]
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+.. function:: machine_mode TARGET_PREFERRED_DOLOOP_MODE (machine_mode mode)
+
+ This hook takes a :samp:`{mode}` for a doloop IV, where ``mode`` is the
+ original mode for the operation. If the target prefers an alternate
+ ``mode`` for the operation, then this hook should return that mode;
+ otherwise the original ``mode`` should be returned. For example, on a
+ 64-bit target, ``DImode`` might be preferred over ``SImode``. Both the
+ original and the returned modes should be ``MODE_INT``.
+
+[TARGET_PREFERRED_DOLOOP_MODE]
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+.. function:: bool TARGET_LEGITIMATE_COMBINED_INSN (rtx_insn *insn)
+
+ Take an instruction in :samp:`{insn}` and return ``false`` if the instruction
+ is not appropriate as a combination of two or more instructions. The
+ default is to accept all instructions.
+
+[TARGET_LEGITIMATE_COMBINED_INSN]
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
+
+ :samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
+ specified. Use this hook if the target needs to add extra validation
+ checks to ``handle_dll_attribute``.
+
+[TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
+
+[TARGET_CONST_ANCHOR]
+.. c:var:: unsigned HOST_WIDE_INT TARGET_CONST_ANCHOR
+
+ On some architectures it can take multiple instructions to synthesize
+ a constant. If there is another constant already in a register that
+ is close enough in value then it is preferable that the new constant
+ is computed from this register using immediate addition or
+ subtraction. We accomplish this through CSE. Besides the value of
+ the constant we also add a lower and an upper constant anchor to the
+ available expressions. These are then queried when encountering new
+ constants. The anchors are computed by rounding the constant up and
+ down to a multiple of the value of ``TARGET_CONST_ANCHOR``.
+ ``TARGET_CONST_ANCHOR`` should be the maximum positive value
+ accepted by immediate-add plus one. We currently assume that the
+ value of ``TARGET_CONST_ANCHOR`` is a power of 2. For example, on
+ MIPS, where add-immediate takes a 16-bit signed value,
+ ``TARGET_CONST_ANCHOR`` is set to :samp:`0x8000`. The default value
+ is zero, which disables this optimization.
+
+[TARGET_CONST_ANCHOR]
+
+[TARGET_MEMMODEL_CHECK]
+.. function:: unsigned HOST_WIDE_INT TARGET_MEMMODEL_CHECK (unsigned HOST_WIDE_INT val)
+
+ Validate target specific memory model mask bits. When NULL no target specific
+ memory model bits are allowed.
+
+[TARGET_MEMMODEL_CHECK]
+
+[TARGET_ASAN_SHADOW_OFFSET]
+.. function:: unsigned HOST_WIDE_INT TARGET_ASAN_SHADOW_OFFSET (void)
+
+ Return the offset bitwise ored into shifted address to get corresponding
+ Address Sanitizer shadow memory address. NULL if Address Sanitizer is not
+ supported by the target. May return 0 if Address Sanitizer is not supported
+ by a subtarget.
+
+[TARGET_ASAN_SHADOW_OFFSET]
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
+
+ Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
+ function return values. The target hook should return the new mode
+ and possibly change ``*punsignedp`` if the promotion should
+ change signedness. This function is called only for scalar *or
+ pointer* types.
+
+ :samp:`{for_return}` allows to distinguish the promotion of arguments and
+ return values. If it is ``1``, a return value is being promoted and
+ ``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
+ If it is ``2``, the returned mode should be that of the register in
+ which an incoming parameter is copied, or the outgoing result is computed;
+ then the hook should return the same mode as ``promote_mode``, though
+ the signedness may be different.
+
+ :samp:`{type}` can be NULL when promoting function arguments of libcalls.
+
+ The default is to not promote arguments and return values. You can
+ also define the hook to ``default_promote_function_mode_always_promote``
+ if you would like to apply the same rules given by ``PROMOTE_MODE``.
+
+[TARGET_PROMOTE_FUNCTION_MODE]
+
+[TARGET_PROMOTE_PROTOTYPES]
+.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
+
+ This target hook returns ``true`` if an argument declared in a
+ prototype as an integral type smaller than ``int`` should actually be
+ passed as an ``int``. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain machines.
+ The default is to not promote prototypes.
+
+[TARGET_PROMOTE_PROTOTYPES]
+
+[TARGET_STRUCT_VALUE_RTX]
+.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
+
+ This target hook should return the location of the structure value
+ address (normally a ``mem`` or ``reg``), or 0 if the address is
+ passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
+ be ``NULL``, for libcalls. You do not need to define this target
+ hook if the address is always passed as an 'invisible' first
+ argument.
+
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+ :samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
+ the context of the called function, and ``0`` in the context of
+ the caller.
+
+ If :samp:`{incoming}` is nonzero and the address is to be found on the
+ stack, return a ``mem`` which refers to the frame pointer. If
+ :samp:`{incoming}` is ``2``, the result is being used to fetch the
+ structure value address at the beginning of a function. If you need
+ to emit adjusting code, you should do it at this point.
+
+[TARGET_STRUCT_VALUE_RTX]
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
+
+ Normally, when a function returns a structure by memory, the address
+ is passed as an invisible pointer argument, but the compiler also
+ arranges to return the address from the function like it would a normal
+ pointer return value. Define this to true if that behavior is
+ undesirable on your target.
+
+[TARGET_OMIT_STRUCT_RETURN_REG]
+
+[TARGET_RETURN_IN_MEMORY]
+.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
+
+ This target hook should return a nonzero value to say to return the
+ function value in memory, just as large structures are always returned.
+ Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
+ will be the type of the function doing the returning, or ``NULL`` for
+ libcalls.
+
+ Note that values of mode ``BLKmode`` must be explicitly handled
+ by this function. Also, the option :option:`-fpcc-struct-return`
+ takes effect regardless of this macro. On most systems, it is
+ possible to leave the hook undefined; this causes a default
+ definition to be used, whose value is the constant 1 for ``BLKmode``
+ values, and 0 otherwise.
+
+ Do not use this hook to indicate that structures and unions should always
+ be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
+ to indicate this.
+
+[TARGET_RETURN_IN_MEMORY]
+
+[TARGET_RETURN_IN_MSB]
+.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
+
+ This hook should return true if values of type :samp:`{type}` are returned
+ at the most significant end of a register (in other words, if they are
+ padded at the least significant end). You can assume that :samp:`{type}`
+ is returned in a register; the caller is required to check this.
+
+ Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
+ be able to hold the complete return value. For example, if a 1-, 2-
+ or 3-byte structure is returned at the most significant end of a
+ 4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
+ ``SImode`` rtx.
+
+[TARGET_RETURN_IN_MSB]
+
+[TARGET_PASS_BY_REFERENCE]
+.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook should return ``true`` if argument :samp:`{arg}` at the
+ position indicated by :samp:`{cum}` should be passed by reference. This
+ predicate is queried after target independent reasons for being
+ passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
+
+ If the hook returns true, a copy of that argument is made in memory and a
+ pointer to the argument is passed instead of the argument itself.
+ The pointer is passed in whatever way is appropriate for passing a pointer
+ to that type.
+
+[TARGET_PASS_BY_REFERENCE]
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
+
+ If defined, this hook produces the machine-specific code for a call to
+ ``__builtin_saveregs``. This code will be moved to the very
+ beginning of the function, before any parameter access are made. The
+ return value of this function should be an RTX that contains the value
+ to use as the return of ``__builtin_saveregs``.
+
+[TARGET_EXPAND_BUILTIN_SAVEREGS]
+
+[TARGET_SETUP_INCOMING_VARARGS]
+.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
+
+ This target hook offers an alternative to using
+ ``__builtin_saveregs`` and defining the hook
+ ``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
+ register arguments into the stack so that all the arguments appear to
+ have been passed consecutively on the stack. Once this is done, you can
+ use the standard implementation of varargs that works for machines that
+ pass all their arguments on the stack.
+
+ The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
+ structure, containing the values that are obtained after processing the
+ named arguments. The argument :samp:`{arg}` describes the last of these named
+ arguments. The argument :samp:`{arg}` should not be used if the function type
+ satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
+ no named arguments and all arguments are accessed with ``va_arg``.
+
+ The target hook should do two things: first, push onto the stack all the
+ argument registers *not* used for the named arguments, and second,
+ store the size of the data thus pushed into the ``int`` -valued
+ variable pointed to by :samp:`{pretend_args_size}`. The value that you
+ store here will serve as additional offset for setting up the stack
+ frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ ``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
+ have just a single category of argument register and use it uniformly
+ for all data types.
+
+ If the argument :samp:`{second_time}` is nonzero, it means that the
+ arguments of the function are being analyzed for the second time. This
+ happens for an inline function, which is not actually compiled until the
+ end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
+ not generate any instructions in this case.
+
+[TARGET_SETUP_INCOMING_VARARGS]
+
+[TARGET_CALL_ARGS]
+.. function:: void TARGET_CALL_ARGS (rtx, tree)
+
+ While generating RTL for a function call, this target hook is invoked once
+ for each argument passed to the function, either a register returned by
+ ``TARGET_FUNCTION_ARG`` or a memory location. It is called just
+ before the point where argument registers are stored. The type of the
+ function to be called is also passed as the second argument; it is
+ ``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
+ invoked just after the code to copy the return reg has been emitted.
+ This functionality can be used to perform special setup of call argument
+ registers if a target needs it.
+ For functions without arguments, the hook is called once with ``pc_rtx``
+ passed instead of an argument register.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_CALL_ARGS]
+
+[TARGET_END_CALL_ARGS]
+.. function:: void TARGET_END_CALL_ARGS (void)
+
+ This target hook is invoked while generating RTL for a function call,
+ just after the point where the return reg is copied into a pseudo. It
+ signals that all the call argument and return registers for the just
+ emitted call are now no longer in use.
+ Most ports do not need to implement anything for this hook.
+
+[TARGET_END_CALL_ARGS]
+
+[TARGET_PUSH_ARGUMENT]
+.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
+
+ This target hook returns ``true`` if push instructions will be
+ used to pass outgoing arguments. When the push instruction usage is
+ optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
+ push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
+ have a push instruction or push instruction should be avoided,
+ ``false`` should be returned. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. If this target hook may return ``true``,
+ ``PUSH_ROUNDING`` must be defined.
+
+[TARGET_PUSH_ARGUMENT]
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
+
+ Define this hook to return ``true`` if the location where a function
+ argument is passed depends on whether or not it is a named argument.
+
+ This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
+ is set for varargs and stdarg functions. If this hook returns
+ ``true``, the :samp:`{named}` argument is always true for named
+ arguments, and false for unnamed arguments. If it returns ``false``,
+ but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
+ then all arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this hook if it always returns ``false``.
+
+[TARGET_STRICT_ARGUMENT_NAMING]
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
+
+ If you need to conditionally change ABIs so that one works with
+ ``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
+ ``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
+ defined, then define this hook to return ``true`` if
+ ``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
+ Otherwise, you should not define this hook.
+
+[TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
+
+[TARGET_SPLIT_COMPLEX_ARG]
+.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
+
+ This hook should return true if parameter of type :samp:`{type}` are passed
+ as two scalar parameters. By default, GCC will attempt to pack complex
+ arguments into the target's word size. Some ABIs require complex arguments
+ to be split and treated as their individual components. For example, on
+ AIX64, complex floats should be passed in a pair of floating point
+ registers, even though a complex float would fit in one 64-bit floating
+ point register.
+
+ The default value of this hook is ``NULL``, which is treated as always
+ false.
+
+[TARGET_SPLIT_COMPLEX_ARG]
+
+[TARGET_MUST_PASS_IN_STACK]
+.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
+
+ This target hook should return ``true`` if we should not pass :samp:`{arg}`
+ solely in registers. The file :samp:`expr.h` defines a
+ definition that is usually appropriate, refer to :samp:`expr.h` for additional
+ documentation.
+
+[TARGET_MUST_PASS_IN_STACK]
+
+[TARGET_CALLEE_COPIES]
+.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
+
+ The function argument described by the parameters to this hook is
+ known to be passed by reference. The hook should return true if the
+ function argument should be copied by the callee instead of copied
+ by the caller.
+
+ For any argument for which the hook returns true, if it can be
+ determined that the argument is not modified, then a copy need
+ not be generated.
+
+ The default version of this hook always returns false.
+
+[TARGET_CALLEE_COPIES]
+
+[TARGET_ARG_PARTIAL_BYTES]
+.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
+
+ This target hook returns the number of bytes at the beginning of an
+ argument that must be put in registers. The value must be zero for
+ arguments that are passed entirely in registers or that are entirely
+ pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically the
+ first few words of arguments are passed in registers, and the rest
+ on the stack. If a multi-word argument (a ``double`` or a
+ structure) crosses that boundary, its first few words must be passed
+ in registers and the rest must be pushed. This macro tells the
+ compiler when this occurs, and how many bytes should go in registers.
+
+ ``TARGET_FUNCTION_ARG`` for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ ``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
+
+[TARGET_ARG_PARTIAL_BYTES]
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
+
+ This hook updates the summarizer variable pointed to by :samp:`{ca}` to
+ advance past argument :samp:`{arg}` in the argument list. Once this is done,
+ the variable :samp:`{cum}` is suitable for analyzing the *following*
+ argument with ``TARGET_FUNCTION_ARG``, etc.
+
+ This hook need not do anything if the argument in question was passed
+ on the stack. The compiler knows how to track the amount of stack space
+ used for arguments without any special help.
+
+[TARGET_FUNCTION_ARG_ADVANCE]
+
+[TARGET_FUNCTION_ARG_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
+
+ This hook returns the number of bytes to add to the offset of an
+ argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
+ This is needed for the SPU, which passes ``char`` and ``short``
+ arguments in the preferred slot that is in the middle of the quad word
+ instead of starting at the top. The default implementation returns 0.
+
+[TARGET_FUNCTION_ARG_OFFSET]
+
+[TARGET_FUNCTION_ARG_PADDING]
+.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
+
+ This hook determines whether, and in which direction, to pad out
+ an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
+ ``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
+ to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
+
+ The *amount* of padding is not controlled by this hook, but by
+ ``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
+ to reach the next multiple of that boundary.
+
+ This hook has a default definition that is right for most systems.
+ For little-endian machines, the default is to pad upward. For
+ big-endian machines, the default is to pad downward for an argument of
+ constant size shorter than an ``int``, and upward otherwise.
+
+[TARGET_FUNCTION_ARG_PADDING]
+
+[TARGET_FUNCTION_ARG]
+.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Return an RTX indicating whether function argument :samp:`{arg}` is passed
+ in a register and if so, which register. Argument :samp:`{ca}` summarizes all
+ the previous arguments.
+
+ The return value is usually either a ``reg`` RTX for the hard
+ register in which to pass the argument, or zero to pass the argument
+ on the stack.
+
+ The value of the expression can also be a ``parallel`` RTX. This is
+ used when an argument is passed in multiple locations. The mode of the
+ ``parallel`` should be the mode of the entire argument. The
+ ``parallel`` holds any number of ``expr_list`` pairs; each one
+ describes where part of the argument is passed. In each
+ ``expr_list`` the first operand must be a ``reg`` RTX for the hard
+ register in which to pass this part of the argument, and the mode of the
+ register RTX indicates how large this part of the argument is. The
+ second operand of the ``expr_list`` is a ``const_int`` which gives
+ the offset in bytes into the entire argument of where this part starts.
+ As a special exception the first ``expr_list`` in the ``parallel``
+ RTX may have a first operand of zero. This indicates that the entire
+ argument is also stored on the stack.
+
+ The last time this hook is called, it is called with ``MODE ==
+ VOIDmode``, and its result is passed to the ``call`` or ``call_value``
+ pattern as operands 2 and 3 respectively.
+
+ .. index:: stdarg.h and register arguments
+
+ The usual way to make the ISO library :samp:`stdarg.h` work on a
+ machine where some arguments are usually passed in registers, is to
+ cause nameless arguments to be passed on the stack instead. This is
+ done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
+ :samp:`{named}` is ``false``.
+
+ .. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
+
+ You may use the hook ``targetm.calls.must_pass_in_stack``
+ in the definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
+ is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
+ argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
+ defined, the argument will be computed in the stack and then loaded into
+ a register.
+
+[TARGET_FUNCTION_ARG]
+
+[TARGET_FUNCTION_INCOMING_ARG]
+.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
+
+ Define this hook if the caller and callee on the target have different
+ views of where arguments are passed. Also define this hook if there are
+ functions that are never directly called, but are invoked by the hardware
+ and which have nonstandard calling conventions.
+
+ In this case ``TARGET_FUNCTION_ARG`` computes the register in
+ which the caller passes the value, and
+ ``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
+ fashion to tell the function being called where the arguments will
+ arrive.
+
+ ``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
+ computation using hard register, which can be forced into a register,
+ so that it can be used to pass special arguments.
+
+ If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
+ ``TARGET_FUNCTION_ARG`` serves both purposes.
+
+[TARGET_FUNCTION_INCOMING_ARG]
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
+
+ This hook returns the alignment boundary, in bits, of an argument
+ with the specified mode and type. The default hook returns
+ ``PARM_BOUNDARY`` for all arguments.
+
+[TARGET_FUNCTION_ARG_BOUNDARY]
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
+
+ Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
+ which is the default value for this hook. You can define this hook to
+ return a different value if an argument size must be rounded to a larger
+ value.
+
+[TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+.. function:: const char * TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (const_tree typelist, const_tree funcdecl, const_tree val)
+
+ If defined, this macro returns the diagnostic message when it is
+ illegal to pass argument :samp:`{val}` to function :samp:`{funcdecl}`
+ with prototype :samp:`{typelist}`.
+
+[TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN]
+
+[TARGET_FUNCTION_VALUE]
+.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
+
+ Define this to return an RTX representing the place where a function
+ returns or receives a value of data type :samp:`{ret_type}`, a tree node
+ representing a data type. :samp:`{fn_decl_or_type}` is a tree node
+ representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
+ function being called. If :samp:`{outgoing}` is false, the hook should
+ compute the register in which the caller will see the return value.
+ Otherwise, the hook should return an RTX representing the place where
+ a function returns a value.
+
+ On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
+ (Actually, on most machines, scalar values are returned in the same
+ place regardless of mode.) The value of the expression is usually a
+ ``reg`` RTX for the hard register where the return value is stored.
+ The value can also be a ``parallel`` RTX, if the return value is in
+ multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
+ ``parallel`` form. Note that the callee will populate every
+ location specified in the ``parallel``, but if the first element of
+ the ``parallel`` contains the whole return value, callers will use
+ that element as the canonical location and ignore the others. The m68k
+ port uses this type of ``parallel`` to return pointers in both
+ :samp:`%a0` (the canonical location) and :samp:`%d0`.
+
+ If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
+ the same promotion rules specified in ``PROMOTE_MODE`` if
+ :samp:`{valtype}` is a scalar type.
+
+ If the precise function being called is known, :samp:`{func}` is a tree
+ node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
+ pointer. This makes it possible to use a different value-returning
+ convention for specific functions when all their calls are
+ known.
+
+ Some target machines have 'register windows' so that the register in
+ which a function returns its value is not the same as the one in which
+ the caller sees the value. For such machines, you should return
+ different RTX depending on :samp:`{outgoing}`.
+
+ ``TARGET_FUNCTION_VALUE`` is not used for return values with
+ aggregate data types, because these are returned in another way. See
+ ``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
+
+[TARGET_FUNCTION_VALUE]
+
+[TARGET_LIBCALL_VALUE]
+.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
+
+ Define this hook if the back-end needs to know the name of the libcall
+ function in order to determine where the result should be returned.
+
+ The mode of the result is given by :samp:`{mode}` and the name of the called
+ library function is given by :samp:`{fun}`. The hook should return an RTX
+ representing the place where the library function result will be returned.
+
+ If this hook is not defined, then LIBCALL_VALUE will be used.
+
+[TARGET_LIBCALL_VALUE]
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
+
+ A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as the
+ second of a pair (for a value of type ``double``, say) need not be
+ recognized by this target hook.
+
+ If the machine has register windows, so that the caller and the called
+ function use different registers for the return value, this target hook
+ should recognize only the caller's register numbers.
+
+ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
+
+[TARGET_FUNCTION_VALUE_REGNO_P]
+
+[TARGET_FNTYPE_ABI]
+.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
+
+ Return the ABI used by a function with type :samp:`{type}` ; see the
+ definition of ``predefined_function_abi`` for details of the ABI
+ descriptor. Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_FNTYPE_ABI]
+
+[TARGET_INSN_CALLEE_ABI]
+.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
+
+ This hook returns a description of the ABI used by the target of
+ call instruction :samp:`{insn}` ; see the definition of
+ ``predefined_function_abi`` for details of the ABI descriptor.
+ Only the global function ``insn_callee_abi`` should call this hook
+ directly.
+
+ Targets only need to define this hook if they support
+ interoperability between several ABIs in the same translation unit.
+
+[TARGET_INSN_CALLEE_ABI]
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+.. function:: void TARGET_UPDATE_STACK_BOUNDARY (void)
+
+ Define this macro to update the current function stack boundary if
+ necessary.
+
+[TARGET_UPDATE_STACK_BOUNDARY]
+
+[TARGET_GET_DRAP_RTX]
+.. function:: rtx TARGET_GET_DRAP_RTX (void)
+
+ This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a
+ different argument pointer register is needed to access the function's
+ argument list due to stack realignment. Return ``NULL`` if no DRAP
+ is needed.
+
+[TARGET_GET_DRAP_RTX]
+
+[TARGET_ZERO_CALL_USED_REGS]
+.. function:: HARD_REG_SET TARGET_ZERO_CALL_USED_REGS (HARD_REG_SET selected_regs)
+
+ This target hook emits instructions to zero the subset of :samp:`{selected_regs}`
+ that could conceivably contain values that are useful to an attacker.
+ Return the set of registers that were actually cleared.
+
+ For most targets, the returned set of registers is a subset of
+ :samp:`{selected_regs}`, however, for some of the targets (for example MIPS),
+ clearing some registers that are in the :samp:`{selected_regs}` requires
+ clearing other call used registers that are not in the :samp:`{selected_regs}`,
+ under such situation, the returned set of registers must be a subset of all
+ call used registers.
+
+ The default implementation uses normal move instructions to zero
+ all the registers in :samp:`{selected_regs}`. Define this hook if the
+ target has more efficient ways of zeroing certain registers,
+ or if you believe that certain registers would never contain
+ values that are useful to an attacker.
+
+[TARGET_ZERO_CALL_USED_REGS]
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+.. function:: bool TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
+
+ When optimization is disabled, this hook indicates whether or not
+ arguments should be allocated to stack slots. Normally, GCC allocates
+ stacks slots for arguments when not optimizing in order to make
+ debugging easier. However, when a function is declared with
+ ``__attribute__((naked))``, there is no stack frame, and the compiler
+ cannot safely move arguments from the registers in which they are passed
+ to the stack. Therefore, this hook should return true in general, but
+ false for naked functions. The default implementation always returns true.
+
+[TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS]
+
+[TARGET_STATIC_CHAIN]
+.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
+
+ This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
+ targets that may use different static chain locations for different
+ nested functions. This may be required if the target has function
+ attributes that affect the calling conventions of the function and
+ those calling conventions use different static chain locations.
+
+ The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
+
+ If the static chain is passed in memory, this hook should be used to
+ provide rtx giving ``mem`` expressions that denote where they are stored.
+ Often the ``mem`` expression as seen by the caller will be at an offset
+ from the stack pointer and the ``mem`` expression as seen by the callee
+ will be at an offset from the frame pointer.
+
+ .. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
+
+ The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
+ ``arg_pointer_rtx`` will have been initialized and should be used
+ to refer to those items.
+
+[TARGET_STATIC_CHAIN]
+
+[TARGET_TRAMPOLINE_INIT]
+.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
+
+ This hook is called to initialize a trampoline.
+ :samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
+ is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
+ RTX for the static chain value that should be passed to the function
+ when it is called.
+
+ If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
+ first thing this hook should do is emit a block move into :samp:`{m_tramp}`
+ from the memory block returned by ``assemble_trampoline_template``.
+ Note that the block move need only cover the constant parts of the
+ trampoline. If the target isolates the variable parts of the trampoline
+ to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
+
+ If the target requires any other actions, such as flushing caches
+ (possibly calling function maybe_emit_call_builtin___clear_cache) or
+ enabling stack execution, these actions should be performed after
+ initializing the trampoline proper.
+
+[TARGET_TRAMPOLINE_INIT]
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
+
+ On targets that do not define a ``clear_cache`` insn expander,
+ but that define the ``CLEAR_CACHE_INSN`` macro,
+ maybe_emit_call_builtin___clear_cache relies on this target hook
+ to clear an address range in the instruction cache.
+
+ The default implementation calls the ``__clear_cache`` builtin,
+ taking the assembler name from the builtin declaration. Overriding
+ definitions may call alternate functions, with alternate calling
+ conventions, or emit alternate RTX to perform the job.
+
+[TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
+
+ This hook should perform any machine-specific adjustment in
+ the address of the trampoline. Its argument contains the address of the
+ memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
+ the address to be used for a function call should be different from the
+ address at which the template was stored, the different address should
+ be returned; otherwise :samp:`{addr}` should be returned unchanged.
+ If this hook is not defined, :samp:`{addr}` will be used for function calls.
+
+[TARGET_TRAMPOLINE_ADJUST_ADDRESS]
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+ If the target can use GCC's generic descriptor mechanism for nested
+ functions, define this hook to a power of 2 representing an unused bit
+ in function pointers which can be used to differentiate descriptors at
+ run time. This value gives the number of bytes by which descriptor
+ pointers are misaligned compared to function pointers. For example, on
+ targets that require functions to be aligned to a 4-byte boundary, a
+ value of either 1 or 2 is appropriate unless the architecture already
+ reserves the bit for another purpose, such as on ARM.
+
+ Define this hook to 0 if the target implements ABI support for
+ function descriptors in its standard calling sequence, like for example
+ HPPA or IA-64.
+
+ Using descriptors for nested functions
+ eliminates the need for trampolines that reside on the stack and require
+ it to be made executable.
+
+[TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
+
+[TARGET_RETURN_POPS_ARGS]
+.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
+
+ This target hook returns the number of bytes of its own arguments that
+ a function pops on returning, or 0 if the function pops no arguments
+ and the caller must therefore pop them all after the function returns.
+
+ :samp:`{fundecl}` is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ ``FUNCTION_DECL`` that describes the declaration of the function.
+ From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
+
+ :samp:`{funtype}` is a C variable whose value is a tree node that
+ describes the function in question. Normally it is a node of type
+ ``FUNCTION_TYPE`` that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, :samp:`{fundecl}`
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can do so
+ by their names. Note that 'library function' in this context means
+ a function used to perform arithmetic, whose name is known specially
+ in the compiler and was not mentioned in the C code being compiled.
+
+ :samp:`{size}` is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling function.
+
+ On the VAX, all functions always pop their arguments, so the definition
+ of this macro is :samp:`{size}`. On the 68000, using the standard
+ calling convention, no functions pop their arguments, so the value of
+ the macro is always 0 in this case. But an alternative calling
+ convention is available in which functions that take a fixed number of
+ arguments pop them but other functions (such as ``printf``) pop
+ nothing (the caller pops all). When this convention is in use,
+ :samp:`{funtype}` is examined to determine whether a function takes a fixed
+ number of arguments.
+
+[TARGET_RETURN_POPS_ARGS]
+
+[TARGET_GET_RAW_RESULT_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw return
+ registers in ``__builtin_return``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_RESULT_MODE]
+
+[TARGET_GET_RAW_ARG_MODE]
+.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
+
+ This target hook returns the mode to be used when accessing raw argument
+ registers in ``__builtin_apply_args``. Define this macro if the value
+ in :samp:`{reg_raw_mode}` is not correct.
+
+[TARGET_GET_RAW_ARG_MODE]
+
+[TARGET_EMPTY_RECORD_P]
+.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
+
+ This target hook returns true if the type is an empty record. The default
+ is to return ``false``.
+
+[TARGET_EMPTY_RECORD_P]
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
+
+ This target hook warns about the change in empty class parameter passing
+ ABI.
+
+[TARGET_WARN_PARAMETER_PASSING_ABI]
+
+[TARGET_USE_PSEUDO_PIC_REG]
+.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
+
+ This hook should return 1 in case pseudo register should be created
+ for pic_offset_table_rtx during function expand.
+
+[TARGET_USE_PSEUDO_PIC_REG]
+
+[TARGET_INIT_PIC_REG]
+.. function:: void TARGET_INIT_PIC_REG (void)
+
+ Perform a target dependent initialization of pic_offset_table_rtx.
+ This hook is called at the start of register allocation.
+
+[TARGET_INIT_PIC_REG]
+
+[TARGET_INVALID_CONVERSION]
+.. function:: const char * TARGET_INVALID_CONVERSION (const_tree fromtype, const_tree totype)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to convert from :samp:`{fromtype}` to :samp:`{totype}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_CONVERSION]
+
+[TARGET_INVALID_UNARY_OP]
+.. function:: const char * TARGET_INVALID_UNARY_OP (int op, const_tree type)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` (where unary plus is denoted by
+ ``CONVERT_EXPR``) to an operand of type :samp:`{type}`, or ``NULL``
+ if validity should be determined by the front end.
+
+[TARGET_INVALID_UNARY_OP]
+
+[TARGET_INVALID_BINARY_OP]
+.. function:: const char * TARGET_INVALID_BINARY_OP (int op, const_tree type1, const_tree type2)
+
+ If defined, this macro returns the diagnostic message when it is
+ invalid to apply operation :samp:`{op}` to operands of types :samp:`{type1}`
+ and :samp:`{type2}`, or ``NULL`` if validity should be determined by
+ the front end.
+
+[TARGET_INVALID_BINARY_OP]
+
+[TARGET_PROMOTED_TYPE]
+.. function:: tree TARGET_PROMOTED_TYPE (const_tree type)
+
+ If defined, this target hook returns the type to which values of
+ :samp:`{type}` should be promoted when they appear in expressions,
+ analogous to the integer promotions, or ``NULL_TREE`` to use the
+ front end's normal promotion rules. This hook is useful when there are
+ target-specific types with special promotion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_PROMOTED_TYPE]
+
+[TARGET_CONVERT_TO_TYPE]
+.. function:: tree TARGET_CONVERT_TO_TYPE (tree type, tree expr)
+
+ If defined, this hook returns the result of converting :samp:`{expr}` to
+ :samp:`{type}`. It should return the converted expression,
+ or ``NULL_TREE`` to apply the front end's normal conversion rules.
+ This hook is useful when there are target-specific types with special
+ conversion rules.
+ This is currently used only by the C and C++ front ends.
+
+[TARGET_CONVERT_TO_TYPE]
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+.. function:: bool TARGET_VERIFY_TYPE_CONTEXT (location_t loc, type_context_kind context, const_tree type, bool silent_p)
+
+ If defined, this hook returns false if there is a target-specific reason
+ why type :samp:`{type}` cannot be used in the source language context described
+ by :samp:`{context}`. When :samp:`{silent_p}` is false, the hook also reports an
+ error against :samp:`{loc}` for invalid uses of :samp:`{type}`.
+
+ Calls to this hook should be made through the global function
+ ``verify_type_context``, which makes the :samp:`{silent_p}` parameter
+ default to false and also handles ``error_mark_node``.
+
+ The default implementation always returns true.
+
+[TARGET_VERIFY_TYPE_CONTEXT]
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
+
+ This hook returns true if it is possible to bitcast values held in
+ registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
+ and if doing so preserves the low-order bits that are common to both modes.
+ The result is only meaningful if :samp:`{rclass}` has registers that can hold
+ both ``from`` and ``to``. The default implementation returns true.
+
+ As an example of when such bitcasting is invalid, loading 32-bit integer or
+ floating-point objects into floating-point registers on Alpha extends them
+ to 64 bits. Therefore loading a 64-bit object and then storing it as a
+ 32-bit object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, :samp:`alpha.h` defines
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
+
+ .. code-block:: c++
+
+ (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
+ || !reg_classes_intersect_p (FLOAT_REGS, rclass))
+
+ Even if storing from a register in mode :samp:`{to}` would be valid,
+ if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
+ than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
+ mode. This happens when the middle-end assumes that it can load
+ or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
+ eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
+ Failure to prevent this kind of mode change will result in the
+ entire ``raw_reg_mode`` being modified instead of the partial
+ value that the middle-end intended.
+
+[TARGET_CAN_CHANGE_MODE_CLASS]
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
+
+ A target hook which can change allocno class for given pseudo from
+ allocno and best class calculated by IRA.
+
+ The default version of this target hook always returns given class.
+
+[TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
+
+[TARGET_LRA_P]
+.. function:: bool TARGET_LRA_P (void)
+
+ A target hook which returns true if we use LRA instead of reload pass.
+
+ The default version of this target hook returns true. New ports
+ should use LRA, and existing ports are encouraged to convert.
+
+[TARGET_LRA_P]
+
+[TARGET_REGISTER_PRIORITY]
+.. function:: int TARGET_REGISTER_PRIORITY (int)
+
+ A target hook which returns the register priority number to which the
+ register :samp:`{hard_regno}` belongs to. The bigger the number, the
+ more preferable the hard register usage (when all other conditions are
+ the same). This hook can be used to prefer some hard register over
+ others in LRA. For example, some x86-64 register usage needs
+ additional prefix which makes instructions longer. The hook can
+ return lower priority number for such registers make them less favorable
+ and as result making the generated code smaller.
+
+ The default version of this target hook returns always zero.
+
+[TARGET_REGISTER_PRIORITY]
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
+
+ A target hook which returns true if we need register usage leveling.
+ That means if a few hard registers are equally good for the
+ assignment, we choose the least used hard register. The register
+ usage leveling may be profitable for some targets. Don't use the
+ usage leveling for targets with conditional execution or targets
+ with big register files as it hurts if-conversion and cross-jumping
+ optimizations.
+
+ The default version of this target hook returns always false.
+
+[TARGET_REGISTER_USAGE_LEVELING_P]
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
+
+ A target hook which returns true if an address with the same structure
+ can have different maximal legitimate displacement. For example, the
+ displacement can depend on memory mode or on operand combinations in
+ the insn.
+
+ The default version of this target hook returns always false.
+
+[TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
+
+[TARGET_SPILL_CLASS]
+.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
+
+ This hook defines a class of registers which could be used for spilling
+ pseudos of the given mode and class, or ``NO_REGS`` if only memory
+ should be used. Not defining this hook is equivalent to returning
+ ``NO_REGS`` for all inputs.
+
+[TARGET_SPILL_CLASS]
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
+
+ This hook should return ``true`` if given class of registers should
+ be an allocno class in any way. Usually RA uses only one register
+ class from all classes containing the same register set. In some
+ complicated cases, you need to have two or more such classes as
+ allocno ones for RA correct work. Not defining this hook is
+ equivalent to returning ``false`` for all inputs.
+
+[TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
+
+[TARGET_CSTORE_MODE]
+.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
+
+ This hook defines the machine mode to use for the boolean result of
+ conditional store patterns. The ICODE argument is the instruction code
+ for the cstore being performed. Not definiting this hook is the same
+ as accepting the mode encoded into operand 0 of the cstore expander
+ patterns.
+
+[TARGET_CSTORE_MODE]
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
+
+ A target hook which lets a backend compute the set of pressure classes to
+ be used by those optimization passes which take register pressure into
+ account, as opposed to letting IRA compute them. It returns the number of
+ register classes stored in the array :samp:`{pressure_classes}`.
+
+[TARGET_COMPUTE_PRESSURE_CLASSES]
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
+
+ Return true if a structure, union or array containing :samp:`{field}` should
+ be accessed using ``BLKMODE``.
+
+ If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
+ mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
+ case where structures of one field would require the structure's mode to
+ retain the field's mode.
+
+ Normally, this is not needed.
+
+[TARGET_MEMBER_TYPE_FORCES_BLK]
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
+
+ Define this hook for enabling divmod transform if the port does not have
+ hardware divmod insn but defines target-specific divmod libfuncs.
+
+[TARGET_EXPAND_DIVMOD_LIBFUNC]
+
+[TARGET_SECONDARY_RELOAD]
+.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
+
+ Many machines have some registers that cannot be copied directly to or
+ from memory or even from other types of registers. An example is the
+ :samp:`MQ` register, which on most machines, can only be copied to or
+ from general registers, but not memory. Below, we shall be using the
+ term 'intermediate register' when a move operation cannot be performed
+ directly, but has to be done by copying the source into the intermediate
+ register first, and then copying the intermediate register to the
+ destination. An intermediate register always has the same mode as
+ source and destination. Since it holds the actual value being copied,
+ reload might apply optimizations to re-use an intermediate register
+ and eliding the copy from the source when it can determine that the
+ intermediate register still holds the required value.
+
+ Another kind of secondary reload is required on some machines which
+ allow copying all registers to and from memory, but require a scratch
+ register for stores to some memory locations (e.g., those with symbolic
+ address on the RT, and those with certain symbolic address on the SPARC
+ when compiling PIC). Scratch registers need not have the same mode
+ as the value being copied, and usually hold a different value than
+ that being copied. Special patterns in the md file are needed to
+ describe how the copy is performed with the help of the scratch register;
+ these patterns also describe the number, register class(es) and mode(s)
+ of the scratch register(s).
+
+ In some cases, both an intermediate and a scratch register are required.
+
+ For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
+ and :samp:`{x}` is an rtx that needs to be copied to a register of class
+ :samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
+ hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
+ needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
+
+ If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
+ an intermediate register, the hook ``secondary_reload`` should
+ return the register class required for this intermediate register.
+ If no intermediate register is required, it should return NO_REGS.
+ If more than one intermediate register is required, describe the one
+ that is closest in the copy chain to the reload register.
+
+ If scratch registers are needed, you also have to describe how to
+ perform the copy from/to the reload register to/from this
+ closest intermediate register. Or if no intermediate register is
+ required, but still a scratch register is needed, describe the
+ copy from/to the reload register to/from the reload operand :samp:`{x}`.
+
+ You do this by setting ``sri->icode`` to the instruction code of a pattern
+ in the md file which performs the move. Operands 0 and 1 are the output
+ and input of this copy, respectively. Operands from operand 2 onward are
+ for scratch operands. These scratch operands must have a mode, and a
+ single-register-class
+
+ .. [later: or memory]
+
+ output constraint.
+
+ When an intermediate register is used, the ``secondary_reload``
+ hook will be called again to determine how to copy the intermediate
+ register to/from the reload operand :samp:`{x}`, so your hook must also
+ have code to handle the register class of the intermediate operand.
+
+ .. [For later: maybe we'll allow multi-alternative reload patterns -
+
+ .. the port maintainer could name a mov<mode> pattern that has clobbers -
+
+ .. and match the constraints of input and output to determine the required
+
+ .. alternative. A restriction would be that constraints used to match
+
+ .. against reloads registers would have to be written as register class
+
+ .. constraints, or we need a new target macro / hook that tells us if an
+
+ .. arbitrary constraint can match an unknown register of a given class.
+
+ .. Such a macro / hook would also be useful in other places.]
+
+ :samp:`{x}` might be a pseudo-register or a ``subreg`` of a
+ pseudo-register, which could either be in a hard register or in memory.
+ Use ``true_regnum`` to find out; it will return -1 if the pseudo is
+ in memory and the hard register number if it is in a register.
+
+ Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
+ currently not supported. For the time being, you will have to continue
+ to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
+
+ ``copy_cost`` also uses this target hook to find out how values are
+ copied. If you want it to include some extra cost for the need to allocate
+ (a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
+ Or if two dependent moves are supposed to have a lower cost than the sum
+ of the individual moves due to expected fortuitous scheduling and/or special
+ forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
+
+[TARGET_SECONDARY_RELOAD]
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
+
+ Certain machines have the property that some registers cannot be copied
+ to some other registers without using memory. Define this hook on
+ those machines to return true if objects of mode :samp:`{m}` in registers
+ of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
+ storing a register of :samp:`{class1}` into memory and loading that memory
+ location into a register of :samp:`{class2}`. The default definition returns
+ false for all inputs.
+
+[TARGET_SECONDARY_MEMORY_NEEDED]
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
+
+ If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
+ when moving between two particular registers of mode :samp:`{mode}`,
+ this hook specifies the mode that the memory should have.
+
+ The default depends on ``TARGET_LRA_P``. Without LRA, the default
+ is to use a word-sized mode for integral modes that are smaller than a
+ a word. This is right thing to do on most machines because it ensures
+ that all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines, such as
+ the DEC Alpha, that store short integers in floating-point registers
+ differently than in integer registers. On those machines, the default
+ widening will not work correctly and you must define this hook to
+ suppress that widening in some cases. See the file :samp:`alpha.cc` for
+ details.
+
+ With LRA, the default is to use :samp:`{mode}` unmodified.
+
+[TARGET_SECONDARY_MEMORY_NEEDED_MODE]
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ A target hook that places additional restrictions on the register class
+ to use when it is necessary to copy value :samp:`{x}` into a register in class
+ :samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
+ another, smaller class.
+
+ The default version of this hook always returns value of ``rclass`` argument.
+
+ Sometimes returning a more restrictive class makes better code. For
+ example, on the 68000, when :samp:`{x}` is an integer constant that is in range
+ for a :samp:`moveq` instruction, the value of this macro is always
+ ``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
+ Requiring a data register guarantees that a :samp:`moveq` will be used.
+
+ One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
+ :samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
+ loaded into some register class. By returning ``NO_REGS`` you can
+ force :samp:`{x}` into a memory location. For example, rs6000 can load
+ immediate values into general-purpose registers, but does not have an
+ instruction for loading an immediate value into a floating-point
+ register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
+ :samp:`{x}` is a floating-point constant. If the constant can't be loaded
+ into any kind of register, code generation will be better if
+ ``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
+ of using ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+ If an insn has pseudos in it after register allocation, reload will go
+ through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
+ to find the best one. Returning ``NO_REGS``, in this case, makes
+ reload add a ``!`` in front of the constraint: the x86 back-end uses
+ this feature to discourage usage of 387 registers when math is done in
+ the SSE registers (and vice versa).
+
+[TARGET_PREFERRED_RELOAD_CLASS]
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
+
+ Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
+ input reloads.
+
+ The default version of this hook always returns value of ``rclass``
+ argument.
+
+ You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
+ reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
+
+[TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
+
+ On some targets, certain modes cannot be held in registers around a
+ standard ABI call and are relatively expensive to spill to the stack.
+ The early rematerialization pass can help in such cases by aggressively
+ recomputing values after calls, so that they don't need to be spilled.
+
+ This hook returns the set of such modes by setting the associated bits
+ in :samp:`{modes}`. The default implementation selects no modes, which has
+ the effect of disabling the early rematerialization pass.
+
+[TARGET_SELECT_EARLY_REMAT_MODES]
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
+
+ A target hook which returns ``true`` if pseudos that have been assigned
+ to registers of class :samp:`{rclass}` would likely be spilled because
+ registers of :samp:`{rclass}` are needed for spill registers.
+
+ The default version of this target hook returns ``true`` if :samp:`{rclass}`
+ has exactly one register and ``false`` otherwise. On most machines, this
+ default should be used. For generally register-starved machines, such as
+ i386, or machines with right register constraints, such as SH, this hook
+ can be used to avoid excessive spilling.
+
+ This hook is also used by some of the global intra-procedural code
+ transformations to throtle code motion, to avoid increasing register
+ pressure.
+
+[TARGET_CLASS_LIKELY_SPILLED_P]
+
+[TARGET_CLASS_MAX_NREGS]
+.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
+
+ A target hook returns the maximum number of consecutive registers
+ of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
+
+ This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
+ In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
+ mode)`` target hook should be the maximum value of
+ ``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
+ values in the class :samp:`{rclass}`.
+
+ This target hook helps control the handling of multiple-word values
+ in the reload pass.
+
+ The default version of this target hook returns the size of :samp:`{mode}`
+ in words.
+
+[TARGET_CLASS_MAX_NREGS]
+
+[TARGET_PREFERRED_RENAME_CLASS]
+.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
+
+ A target hook that places additional preference on the register
+ class to use when it is necessary to rename a register in class
+ :samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
+ preferred register class is found or hook ``preferred_rename_class``
+ is not implemented.
+ Sometimes returning a more restrictive class makes better code. For
+ example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
+ smaller than instructions using ``GENERIC_REGS``. By returning
+ ``LO_REGS`` from ``preferred_rename_class``, code size can
+ be reduced.
+
+[TARGET_PREFERRED_RENAME_CLASS]
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
+
+ A target hook which returns ``true`` if :samp:`{subst}` can't
+ substitute safely pseudos with equivalent memory values during
+ register allocation.
+ The default version of this target hook returns ``false``.
+ On most machines, this default should be used. For generally
+ machines with non orthogonal register usage for addressing, such
+ as SH, this hook can be used to avoid excessive spilling.
+
+[TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
+
+ This hook tries to split address offset :samp:`{orig_offset}` into
+ two parts: one that should be added to the base address to create
+ a local anchor point, and an additional offset that can be applied
+ to the anchor to address a value of mode :samp:`{mode}`. The idea is that
+ the local anchor could be shared by other accesses to nearby locations.
+
+ The hook returns true if it succeeds, storing the offset of the
+ anchor from the base in :samp:`{offset1}` and the offset of the final address
+ from the anchor in :samp:`{offset2}`. The default implementation returns false.
+
+[TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
+
+ This hook is called just before expansion into rtl, allowing the target
+ to perform additional initializations or analysis before the expansion.
+ For example, the rs6000 port uses it to allocate a scratch stack slot
+ for use in copying SDmode values between memory and floating point
+ registers whenever the function being expanded has any SDmode
+ usage.
+
+[TARGET_EXPAND_TO_RTL_HOOK]
+
+[TARGET_INSTANTIATE_DECLS]
+.. function:: void TARGET_INSTANTIATE_DECLS (void)
+
+ This hook allows the backend to perform additional instantiations on rtl
+ that are not actually in any insns yet, but will be later.
+
+[TARGET_INSTANTIATE_DECLS]
+
+[TARGET_HARD_REGNO_NREGS]
+.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
+
+ This hook returns the number of consecutive hard registers, starting
+ at register number :samp:`{regno}`, required to hold a value of mode
+ :samp:`{mode}`. This hook must never return zero, even if a register
+ cannot hold the requested mode - indicate that with
+ ``TARGET_HARD_REGNO_MODE_OK`` and/or
+ ``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
+
+ The default definition returns the number of words in :samp:`{mode}`.
+
+[TARGET_HARD_REGNO_NREGS]
+
+[TARGET_HARD_REGNO_MODE_OK]
+.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
+
+ This hook returns true if it is permissible to store a value
+ of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
+ registers starting with that one). The default definition returns true
+ unconditionally.
+
+ You need not include code to check for the numbers of fixed registers,
+ because the allocation mechanism considers them to be always occupied.
+
+ .. index:: register pairs
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this hook to reject
+ odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that the
+ :samp:`mov{mode}` instruction pattern support moves between the
+ register and other hard register in the same class and that moving a
+ value into the register and back out not alter it.
+
+ Since the same instruction used to move ``word_mode`` will work for
+ all narrower integer modes, it is not necessary on any machine for
+ this hook to distinguish between these modes, provided you define
+ patterns :samp:`movhi`, etc., to take advantage of this. This is
+ useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
+ and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
+ modes to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed only
+ in floating point registers. This is not true. Any registers that
+ can hold integers can safely *hold* a floating point machine
+ mode, whether or not floating arithmetic can be done on it in those
+ registers. Integer move instructions can be used to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the floating
+ registers normalize any value stored in them, because storing a
+ non-floating value there would garble it. In this case,
+ ``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not automatically
+ normalize, if you can store any bit pattern in one and retrieve it
+ unchanged without a trap, then any machine mode may go in a floating
+ register, so you can define this hook to say so.
+
+ The primary significance of special floating registers is rather that
+ they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ ``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to access,
+ so that it is better to store a value in a stack frame than in such a
+ register if floating point arithmetic is not being done. As long as the
+ floating registers are not in class ``GENERAL_REGS``, they will not
+ be used unless some pattern's constraint asks for one.
+
+[TARGET_HARD_REGNO_MODE_OK]
+
+[TARGET_MODES_TIEABLE_P]
+.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
+
+ This hook returns true if a value of mode :samp:`{mode1}` is accessible
+ in mode :samp:`{mode2}` without copying.
+
+ If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
+ ``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
+ the same for any :samp:`{r}`, then
+ ``TARGET_MODES_TIEABLE_P (mode1, mode2)``
+ should be true. If they differ for any :samp:`{r}`, you should define
+ this hook to return false unless some other mechanism ensures the
+ accessibility of the value in a narrower mode.
+
+ You should define this hook to return true in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation. The default definition returns true unconditionally.
+
+[TARGET_MODES_TIEABLE_P]
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
+
+ This target hook should return ``true`` if it is OK to use a hard register
+ :samp:`{regno}` as scratch reg in peephole2.
+
+ One common use of this macro is to prevent using of a register that
+ is not saved by a prologue in an interrupt handler.
+
+ The default version of this hook always returns ``true``.
+
+[TARGET_HARD_REGNO_SCRATCH_OK]
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
+
+ ABIs usually specify that calls must preserve the full contents
+ of a particular register, or that calls can alter any part of a
+ particular register. This information is captured by the target macro
+ ``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
+ must preserve certain bits of a particular register but can alter others.
+ This hook should return true if this applies to at least one of the
+ registers in :samp:`(reg:{mode}{regno})`, and if as a result the
+ call would alter part of the :samp:`{mode}` value. For example, if a call
+ preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
+ clobber the upper 32 bits, this hook should return true for a 64-bit mode
+ but false for a 32-bit mode.
+
+ The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
+ structure that describes the ABI of the call; see the definition of the
+ structure for more details. If (as is usual) the target uses the same ABI
+ for all functions in a translation unit, :samp:`{abi_id}` is always 0.
+
+ The default implementation returns false, which is correct
+ for targets that don't have partly call-clobbered registers.
+
+[TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
+
+ This hook returns name of multilib ABI name.
+
+[TARGET_GET_MULTILIB_ABI_NAME]
+
+[TARGET_CASE_VALUES_THRESHOLD]
+.. function:: unsigned int TARGET_CASE_VALUES_THRESHOLD (void)
+
+ This function return the smallest number of different values for which it
+ is best to use a jump-table instead of a tree of conditional branches.
+ The default is four for machines with a ``casesi`` instruction and
+ five otherwise. This is best for most machines.
+
+[TARGET_CASE_VALUES_THRESHOLD]
+
+[TARGET_STARTING_FRAME_OFFSET]
+.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
+
+ This hook returns the offset from the frame pointer to the first local
+ variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
+ offset to *end* of the first slot allocated, otherwise it is the
+ offset to *beginning* of the first slot allocated. The default
+ implementation returns 0.
+
+[TARGET_STARTING_FRAME_OFFSET]
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
+
+ This target hook is called once each time the frame layout needs to be
+ recalculated. The calculations can be cached by the target and can then
+ be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
+ layout on every invocation of that hook. This is particularly useful
+ for targets that have an expensive frame layout function. Implementing
+ this callback is optional.
+
+[TARGET_COMPUTE_FRAME_LAYOUT]
+
+[TARGET_FRAME_POINTER_REQUIRED]
+.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
+
+ This target hook should return ``true`` if a function must have and use
+ a frame pointer. This target hook is called in the reload pass. If its return
+ value is ``true`` the function will have a frame pointer.
+
+ This target hook can in principle examine the current function and decide
+ according to the facts, but on most machines the constant ``false`` or the
+ constant ``true`` suffices. Use ``false`` when the machine allows code
+ to be generated with no frame pointer, and doing so saves some time or space.
+ Use ``true`` when there is no possible advantage to avoiding a frame
+ pointer.
+
+ In certain cases, the compiler does not know how to produce valid code
+ without a frame pointer. The compiler recognizes those cases and
+ automatically gives the function a frame pointer regardless of what
+ ``targetm.frame_pointer_required`` returns. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame pointer
+ register can be allocated for ordinary usage, unless you mark it as a
+ fixed register. See ``FIXED_REGISTERS`` for more information.
+
+ Default return value is ``false``.
+
+[TARGET_FRAME_POINTER_REQUIRED]
+
+[TARGET_CAN_ELIMINATE]
+.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
+
+ This target hook should return ``true`` if the compiler is allowed to
+ try to replace register number :samp:`{from_reg}` with register number
+ :samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
+ cases preventing register elimination are things that the compiler already
+ knows about.
+
+ Default return value is ``true``.
+
+[TARGET_CAN_ELIMINATE]
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
+
+ This hook may conditionally modify five variables
+ ``fixed_regs``, ``call_used_regs``, ``global_regs``,
+ ``reg_names``, and ``reg_class_contents``, to take into account
+ any dependence of these register sets on target flags. The first three
+ of these are of type ``char []`` (interpreted as boolean vectors).
+ ``global_regs`` is a ``const char *[]``, and
+ ``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
+ called, ``fixed_regs``, ``call_used_regs``,
+ ``reg_class_contents``, and ``reg_names`` have been initialized
+ from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
+ ``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
+ ``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
+ :option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
+ command options have been applied.
+
+ .. index:: disabling certain registers, controlling register usage
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ ``fixed_regs`` and ``call_used_regs`` to 1 for each of the
+ registers in the classes which should not be used by GCC. Also make
+ ``define_register_constraint`` s return ``NO_REGS`` for constraints
+ that shouldn't be used.
+
+ (However, if this class is not included in ``GENERAL_REGS`` and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid using
+ these registers when the target switches are opposed to them.)
+
+[TARGET_CONDITIONAL_REGISTER_USAGE]
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
+
+ Some targets have an ABI defined interval for which no probing needs to be done.
+ When a probe does need to be done this same interval is used as the probe distance
+ up when doing stack clash protection for alloca.
+ On such targets this value can be set to override the default probing up interval.
+ Define this variable to return nonzero if such a probe range is required or zero otherwise.
+ Defining this hook also requires your functions which make use of alloca to have at least 8 byes
+ of outgoing arguments. If this is not the case the stack will be corrupted.
+ You need not define this macro if it would always have the value zero.
+
+[TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
+
+[TARGET_C_EXCESS_PRECISION]
+.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
+ ``EXCESS_PRECISION_TYPE_FAST``,
+ ``EXCESS_PRECISION_TYPE_STANDARD``, or
+ ``EXCESS_PRECISION_TYPE_FLOAT16``. For
+ ``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
+ precision and range operations will be implictly evaluated in regardless
+ of the excess precision explicitly added. For
+ ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16``, and
+ ``EXCESS_PRECISION_TYPE_FAST``, the target should return the
+ explicit excess precision that should be added depending on the
+ value set for :option:`-fexcess-precision=[standard|fast|16]`.
+ Note that unpredictable explicit excess precision does not make sense,
+ so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
+ when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
+ ``EXCESS_PRECISION_TYPE_FLOAT16`` or
+ ``EXCESS_PRECISION_TYPE_FAST``.
+
+ Return a value, with the same meaning as the C99 macro
+ ``FLT_EVAL_METHOD`` that describes which excess precision should be
+ applied.
+
+[TARGET_C_EXCESS_PRECISION]
+
+[TARGET_CXX_GUARD_TYPE]
+.. function:: tree TARGET_CXX_GUARD_TYPE (void)
+
+ Define this hook to override the integer type used for guard variables.
+ These are used to implement one-time construction of static objects. The
+ default is long_long_integer_type_node.
+
+[TARGET_CXX_GUARD_TYPE]
+
+[TARGET_CXX_GUARD_MASK_BIT]
+.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
+
+ This hook determines how guard variables are used. It should return
+ ``false`` (the default) if the first byte should be used. A return value of
+ ``true`` indicates that only the least significant bit should be used.
+
+[TARGET_CXX_GUARD_MASK_BIT]
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
+
+ This hook returns the size of the cookie to use when allocating an array
+ whose elements have the indicated :samp:`{type}`. Assumes that it is already
+ known that a cookie is needed. The default is
+ ``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
+ IA64/Generic C++ ABI.
+
+[TARGET_CXX_GET_COOKIE_SIZE]
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
+
+ This hook should return ``true`` if the element size should be stored in
+ array cookies. The default is to return ``false``.
+
+[TARGET_CXX_COOKIE_HAS_SIZE]
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
+
+ If defined by a backend this hook allows the decision made to export
+ class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
+ will contain 1 if the class is going to be exported, -1 if it is going
+ to be imported and 0 otherwise. This function should return the
+ modified value and perform any other actions necessary to support the
+ backend's targeted operating system.
+
+[TARGET_CXX_IMPORT_EXPORT_CLASS]
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
+
+ This hook should return ``true`` if constructors and destructors return
+ the address of the object created/destroyed. The default is to return
+ ``false``.
+
+[TARGET_CXX_CDTOR_RETURNS_THIS]
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
+
+ This hook returns true if the key method for a class (i.e., the method
+ which, if defined in the current translation unit, causes the virtual
+ table to be emitted) may be an inline function. Under the standard
+ Itanium C++ ABI the key method may be an inline function so long as
+ the function is not declared inline in the class definition. Under
+ some variants of the ABI, an inline function can never be the key
+ method. The default is to return ``true``.
+
+[TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
+
+ :samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
+ or other similar implicit class data object that will be emitted with
+ external linkage in this translation unit. No ELF visibility has been
+ explicitly specified. If the target needs to specify a visibility
+ other than that of the containing class, use this hook to set
+ ``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
+
+[TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
+
+ This hook returns true (the default) if virtual tables and other
+ similar implicit class data objects are always COMDAT if they have
+ external linkage. If this hook returns false, then class data for
+ classes whose virtual table will be emitted in only one translation
+ unit will not be COMDAT.
+
+[TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
+
+ This hook returns true (the default) if the RTTI information for
+ the basic types which is defined in the C++ runtime should always
+ be COMDAT, false if it should not be COMDAT.
+
+[TARGET_CXX_LIBRARY_RTTI_COMDAT]
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
+
+ This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
+ should be used to register static destructors when :option:`-fuse-cxa-atexit`
+ is in effect. The default is to return false to use ``__cxa_atexit``.
+
+[TARGET_CXX_USE_AEABI_ATEXIT]
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
+
+ This hook returns true if the target ``atexit`` function can be used
+ in the same manner as ``__cxa_atexit`` to register C++ static
+ destructors. This requires that ``atexit`` -registered functions in
+ shared libraries are run in the correct order when the libraries are
+ unloaded. The default is to return false.
+
+[TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
+
+ :samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
+ been defined. Use this hook to make adjustments to the class (eg, tweak
+ visibility or perform any other required target modifications).
+
+[TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
+
+ Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
+
+[TARGET_CXX_DECL_MANGLING_CONTEXT]
+
+[TARGET_EMUTLS_GET_ADDRESS]
+.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
+
+ Contains the name of the helper function that uses a TLS control
+ object to locate a TLS instance. The default causes libgcc's
+ emulated TLS helper function to be used.
+
+[TARGET_EMUTLS_GET_ADDRESS]
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
+
+ Contains the name of the helper function that should be used at
+ program startup to register TLS objects that are implicitly
+ initialized to zero. If this is ``NULL``, all TLS objects will
+ have explicit initializers. The default causes libgcc's emulated TLS
+ registration function to be used.
+
+[TARGET_EMUTLS_REGISTER_COMMON]
+
+[TARGET_EMUTLS_VAR_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
+
+ Contains the name of the section in which TLS control variables should
+ be placed. The default of ``NULL`` allows these to be placed in
+ any section.
+
+[TARGET_EMUTLS_VAR_SECTION]
+
+[TARGET_EMUTLS_TMPL_SECTION]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
+
+ Contains the name of the section in which TLS initializers should be
+ placed. The default of ``NULL`` allows these to be placed in any
+ section.
+
+[TARGET_EMUTLS_TMPL_SECTION]
+
+[TARGET_EMUTLS_VAR_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
+
+ Contains the prefix to be prepended to TLS control variable names.
+ The default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_VAR_PREFIX]
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
+
+ Contains the prefix to be prepended to TLS initializer objects. The
+ default of ``NULL`` uses a target-specific prefix.
+
+[TARGET_EMUTLS_TMPL_PREFIX]
+
+[TARGET_EMUTLS_VAR_FIELDS]
+.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
+
+ Specifies a function that generates the FIELD_DECLs for a TLS control
+ object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
+ :samp:`{name}` should be filled with the structure tag, if the default of
+ ``__emutls_object`` is unsuitable. The default creates a type suitable
+ for libgcc's emulated TLS function.
+
+[TARGET_EMUTLS_VAR_FIELDS]
+
+[TARGET_EMUTLS_VAR_INIT]
+.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
+
+ Specifies a function that generates the CONSTRUCTOR to initialize a
+ TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
+ is the TLS object and :samp:`{tmpl_addr}` is the address of the
+ initializer. The default initializes libgcc's emulated TLS control object.
+
+[TARGET_EMUTLS_VAR_INIT]
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
+
+ Specifies whether the alignment of TLS control variable objects is
+ fixed and should not be increased as some backends may do to optimize
+ single objects. The default is false.
+
+[TARGET_EMUTLS_VAR_ALIGN_FIXED]
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+
+ Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
+ may be used to describe emulated TLS control objects.
+
+[TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
+
+ This hook is called to parse ``attribute(target("..."))``, which
+ allows setting target-specific options on individual functions.
+ These function-specific options may differ
+ from the options specified on the command line. The hook should return
+ ``true`` if the options are valid.
+
+ The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
+ the function declaration to hold a pointer to a target-specific
+ ``struct cl_target_option`` structure.
+
+[TARGET_OPTION_VALID_ATTRIBUTE_P]
+
+[TARGET_OPTION_SAVE]
+.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
+
+ This hook is called to save any additional target-specific information
+ in the ``struct cl_target_option`` structure for function-specific
+ options from the ``struct gcc_options`` structure.
+ See :ref:`option-file-format`.
+
+[TARGET_OPTION_SAVE]
+
+[TARGET_OPTION_RESTORE]
+.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
+
+ This hook is called to restore any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options to the ``struct gcc_options`` structure.
+
+[TARGET_OPTION_RESTORE]
+
+[TARGET_OPTION_POST_STREAM_IN]
+.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
+
+ This hook is called to update target-specific information in the
+ ``struct cl_target_option`` structure after it is streamed in from
+ LTO bytecode.
+
+[TARGET_OPTION_POST_STREAM_IN]
+
+[TARGET_OPTION_PRINT]
+.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
+
+ This hook is called to print any additional target-specific
+ information in the ``struct cl_target_option`` structure for
+ function-specific options.
+
+[TARGET_OPTION_PRINT]
+
+[TARGET_OPTION_PRAGMA_PARSE]
+.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
+
+ This target hook parses the options for ``#pragma GCC target``, which
+ sets the target-specific options for functions that occur later in the
+ input stream. The options accepted should be the same as those handled by the
+ ``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
+
+[TARGET_OPTION_PRAGMA_PARSE]
+
+[TARGET_OPTION_OVERRIDE]
+.. function:: void TARGET_OPTION_OVERRIDE (void)
+
+ Sometimes certain combinations of command options do not make sense on
+ a particular target machine. You can override the hook
+ ``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
+ once just after all the command options have been parsed.
+
+ Don't use this hook to turn on various extra optimizations for
+ :option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
+
+ If you need to do something whenever the optimization level is
+ changed via the optimize attribute or pragma, see
+ ``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
+
+[TARGET_OPTION_OVERRIDE]
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
+
+ This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
+ versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
+ versions if and only if they have the same function signature and
+ different target specific attributes, that is, they are compiled for
+ different target machines.
+
+[TARGET_OPTION_FUNCTION_VERSIONS]
+
+[TARGET_CAN_INLINE_P]
+.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
+
+ This target hook returns ``false`` if the :samp:`{caller}` function
+ cannot inline :samp:`{callee}`, based on target specific information. By
+ default, inlining is not allowed if the callee function has function
+ specific target options and the caller does not use the same options.
+
+[TARGET_CAN_INLINE_P]
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
+
+ Allow target to analyze all gimple statements for the given function to
+ record and update some target specific information for inlining. A typical
+ example is that a caller with one isa feature disabled is normally not
+ allowed to inline a callee with that same isa feature enabled even which is
+ attributed by always_inline, but with the conservative analysis on all
+ statements of the callee if we are able to guarantee the callee does not
+ exploit any instructions from the mismatch isa feature, it would be safe to
+ allow the caller to inline the callee.
+ :samp:`{info}` is one ``unsigned int`` value to record information in which
+ one set bit indicates one corresponding feature is detected in the analysis,
+ :samp:`{stmt}` is the statement being analyzed. Return true if target still
+ need to analyze the subsequent statements, otherwise return false to stop
+ subsequent analysis.
+ The default version of this hook returns false.
+
+[TARGET_UPDATE_IPA_FN_TARGET_INFO]
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
+
+ Allow target to check early whether it is necessary to analyze all gimple
+ statements in the given function to update target specific information for
+ inlining. See hook ``update_ipa_fn_target_info`` for usage example of
+ target specific information. This hook is expected to be invoked ahead of
+ the iterating with hook ``update_ipa_fn_target_info``.
+ :samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
+ in hook ``update_ipa_fn_target_info``, target can do one time update
+ into :samp:`{info}` without iterating for some case. Return true if target
+ decides to analyze all gimple statements to collect information, otherwise
+ return false.
+ The default version of this hook returns false.
+
+[TARGET_NEED_IPA_FN_TARGET_INFO]
+
+[TARGET_RELAYOUT_FUNCTION]
+.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
+
+ This target hook fixes function :samp:`{fndecl}` after attributes are processed.
+ Default does nothing. On ARM, the default function's alignment is updated
+ with the attribute target.
+
+[TARGET_RELAYOUT_FUNCTION]
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
+
+ Add any hard registers to :samp:`{regs}` that are live on entry to the
+ function. This hook only needs to be defined to provide registers that
+ cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
+ registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
+ TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
+ FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
+
+[TARGET_EXTRA_LIVE_ON_ENTRY]
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
+
+ Set to true if each call that binds to a local definition explicitly
+ clobbers or sets all non-fixed registers modified by performing the call.
+ That is, by the call pattern itself, or by code that might be inserted by the
+ linker (e.g. stubs, veneers, branch islands), but not including those
+ modifiable by the callee. The affected registers may be mentioned explicitly
+ in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
+ The default version of this hook is set to false. The purpose of this hook
+ is to enable the fipa-ra optimization.
+
+[TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
+
+[TARGET_SET_UP_BY_PROLOGUE]
+.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
+
+ This hook should add additional registers that are computed by the prologue
+ to the hard regset for shrink-wrapping optimization purposes.
+
+[TARGET_SET_UP_BY_PROLOGUE]
+
+[TARGET_WARN_FUNC_RETURN]
+.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
+
+ True if a function's return statements should be checked for matching
+ the function's return type. This includes checking for falling off the end
+ of a non-void function. Return false if no such check should be made.
+
+[TARGET_WARN_FUNC_RETURN]
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components that can be separately shrink-wrapped in the current function.
+ Return ``NULL`` if the current function should not get any separate
+ shrink-wrapping.
+ Don't define this hook if it would always return ``NULL``.
+ If it is defined, the other hooks in this group have to be defined as well.
+
+[TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
+
+ This hook should return an ``sbitmap`` with the bits set for those
+ components where either the prologue component has to be executed before
+ the ``basic_block``, or the epilogue component after it, or both.
+
+[TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
+
+ This hook should clear the bits in the :samp:`{components}` bitmap for those
+ components in :samp:`{edge_components}` that the target cannot handle on edge
+ :samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
+ epilogue instead.
+
+[TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
+
+ Emit prologue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
+
+ Emit epilogue insns for the components indicated by the parameter.
+
+[TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
+
+ Mark the components in the parameter as handled, so that the
+ ``prologue`` and ``epilogue`` named patterns know to ignore those
+ components. The target code should not hang on to the ``sbitmap``, it
+ will be deleted after this call.
+
+[TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
+
+[TARGET_DEBUG_UNWIND_INFO]
+.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
+
+ This hook defines the mechanism that will be used for describing frame
+ unwind information to the debugger. Normally the hook will return
+ ``UI_DWARF2`` if DWARF 2 debug information is enabled, and
+ return ``UI_NONE`` otherwise.
+
+ A target may return ``UI_DWARF2`` even when DWARF 2 debug information
+ is disabled in order to always output DWARF 2 frame information.
+
+ A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
+ This will suppress generation of the normal debug frame unwind information.
+
+[TARGET_DEBUG_UNWIND_INFO]
+
+[TARGET_RESET_LOCATION_VIEW]
+.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
+
+ This hook, if defined, enables -ginternal-reset-location-views, and
+ uses its result to override cases in which the estimated min insn
+ length might be nonzero even when a PC advance (i.e., a view reset)
+ cannot be taken for granted.
+
+ If the hook is defined, it must return a positive value to indicate
+ the insn definitely advances the PC, and so the view number can be
+ safely assumed to be reset; a negative value to mean the insn
+ definitely does not advance the PC, and os the view number must not
+ be reset; or zero to decide based on the estimated insn length.
+
+ If insn length is to be regarded as reliable, set the hook to
+ ``hook_int_rtx_insn_0``.
+
+[TARGET_RESET_LOCATION_VIEW]
+
+[TARGET_CANONICALIZE_COMPARISON]
+.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
+
+ On some machines not all possible comparisons are defined, but you can
+ convert an invalid comparison into a valid one. For example, the Alpha
+ does not have a ``GT`` comparison, but you can use an ``LT``
+ comparison instead and swap the order of the operands.
+
+ On such machines, implement this hook to do any required conversions.
+ :samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
+ are the left and right operands of the comparison, respectively. If
+ :samp:`{op0_preserve_value}` is ``true`` the implementation is not
+ allowed to change the value of :samp:`{op0}` since the value might be used
+ in RTXs which aren't comparisons. E.g. the implementation is not
+ allowed to swap operands in that case.
+
+ GCC will not assume that the comparison resulting from this macro is
+ valid but will see if the resulting insn matches a pattern in the
+ :samp:`md` file.
+
+ You need not to implement this hook if it would never change the
+ comparison code or operands.
+
+[TARGET_CANONICALIZE_COMPARISON]
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+.. function:: unsigned int TARGET_MIN_ARITHMETIC_PRECISION (void)
+
+ On some RISC architectures with 64-bit registers, the processor also
+ maintains 32-bit condition codes that make it possible to do real 32-bit
+ arithmetic, although the operations are performed on the full registers.
+
+ On such architectures, defining this hook to 32 tells the compiler to try
+ using 32-bit arithmetical operations setting the condition codes instead
+ of doing full 64-bit arithmetic.
+
+ More generally, define this hook on RISC architectures if you want the
+ compiler to try using arithmetical operations setting the condition codes
+ with a precision lower than the word precision.
+
+ You need not define this hook if ``WORD_REGISTER_OPERATIONS`` is not
+ defined to 1.
+
+[TARGET_MIN_ARITHMETIC_PRECISION]
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+.. c:var:: unsigned char TARGET_ATOMIC_TEST_AND_SET_TRUEVAL
+
+ This value should be set if the result written by
+ ``atomic_test_and_set`` is not exactly 1, i.e. the
+ ``bool`` ``true``.
+
+[TARGET_ATOMIC_TEST_AND_SET_TRUEVAL]
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+.. function:: unsigned int TARGET_ATOMIC_ALIGN_FOR_MODE (machine_mode mode)
+
+ If defined, this function returns an appropriate alignment in bits for an
+ atomic object of machine_mode :samp:`{mode}`. If 0 is returned then the
+ default alignment for the specified mode is used.
+
+[TARGET_ATOMIC_ALIGN_FOR_MODE]
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+.. function:: void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree *hold, tree *clear, tree *update)
+
+ ISO C11 requires atomic compound assignments that may raise floating-point
+ exceptions to raise exceptions corresponding to the arithmetic operation
+ whose result was successfully stored in a compare-and-exchange sequence.
+ This requires code equivalent to calls to ``feholdexcept``,
+ ``feclearexcept`` and ``feupdateenv`` to be generated at
+ appropriate points in the compare-and-exchange sequence. This hook should
+ set ``*hold`` to an expression equivalent to the call to
+ ``feholdexcept``, ``*clear`` to an expression equivalent to
+ the call to ``feclearexcept`` and ``*update`` to an expression
+ equivalent to the call to ``feupdateenv``. The three expressions are
+ ``NULL_TREE`` on entry to the hook and may be left as ``NULL_TREE``
+ if no code is required in a particular place. The default implementation
+ leaves all three expressions as ``NULL_TREE``. The
+ ``__atomic_feraiseexcept`` function from ``libatomic`` may be of use
+ as part of the code generated in ``*update``.
+
+[TARGET_ATOMIC_ASSIGN_EXPAND_FENV]
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
+
+ This flag is true if we can create zeroed data by switching to a BSS
+ section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
+ This is true on most ELF targets.
+
+[TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
+
+[TARGET_HAVE_CTORS_DTORS]
+.. c:var:: bool TARGET_HAVE_CTORS_DTORS
+
+ This value is true if the target supports some 'native' method of
+ collecting constructors and destructors to be run at startup and exit.
+ It is false if we must use :command:`collect2`.
+
+[TARGET_HAVE_CTORS_DTORS]
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
+
+ This value is true if the target wants destructors to be queued to be
+ run from __cxa_atexit. If this is the case then, for each priority level,
+ a new constructor will be entered that registers the destructors for that
+ level with __cxa_atexit (and there will be no destructors emitted).
+ It is false the method implied by ``have_ctors_dtors`` is used.
+
+[TARGET_DTORS_FROM_CXA_ATEXIT]
+
+[TARGET_HAVE_TLS]
+.. c:var:: bool TARGET_HAVE_TLS
+
+ Contains the value true if the target supports thread-local storage.
+ The default value is false.
+
+[TARGET_HAVE_TLS]
+
+[TARGET_HAVE_SRODATA_SECTION]
+.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
+
+ Contains the value true if the target places read-only
+ 'small data' into a separate section. The default value is false.
+
+[TARGET_HAVE_SRODATA_SECTION]
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
+
+ Contains the value true if the target should add a zero word onto the
+ end of a Dwarf-2 frame info section when used for exception handling.
+ Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
+ true otherwise.
+
+[TARGET_TERMINATE_DW2_EH_FRAME_INFO]
+
+[TARGET_ASM_FILE_START_APP_OFF]
+.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
+
+ If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
+ printed as the very first line in the assembly file, unless
+ :option:`-fverbose-asm` is in effect. (If that macro has been defined
+ to the empty string, this variable has no effect.) With the normal
+ definition of ``ASM_APP_OFF``, the effect is to notify the GNU
+ assembler that it need not bother stripping comments or extra
+ whitespace from its input. This allows it to work a bit faster.
+
+ The default is false. You should not set it to true unless you have
+ verified that your port does not generate any extra whitespace or
+ comments that will cause GAS to issue errors in NO_APP mode.
+
+[TARGET_ASM_FILE_START_APP_OFF]
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
+
+ If this flag is true, ``output_file_directive`` will be called
+ for the primary source file, immediately after printing
+ ``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
+ this to be done. The default is false.
+
+[TARGET_ASM_FILE_START_FILE_DIRECTIVE]
+
+[TARGET_ARM_EABI_UNWINDER]
+.. c:var:: bool TARGET_ARM_EABI_UNWINDER
+
+ This flag should be set to ``true`` on targets that use an ARM EABI
+ based unwinding library, and ``false`` on other targets. This effects
+ the format of unwinding tables, and how the unwinder in entered after
+ running a cleanup. The default is ``false``.
+
+[TARGET_ARM_EABI_UNWINDER]
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
+
+ True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
+ should be emitted. These sections are not used on most platforms, and
+ in particular GDB does not use them.
+
+[TARGET_WANT_DEBUG_PUB_SECTIONS]
+
+[TARGET_DELAY_SCHED2]
+.. c:var:: bool TARGET_DELAY_SCHED2
+
+ True if sched2 is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_SCHED2]
+
+[TARGET_DELAY_VARTRACK]
+.. c:var:: bool TARGET_DELAY_VARTRACK
+
+ True if vartrack is not to be run at its normal place.
+ This usually means it will be run as part of machine-specific reorg.
+
+[TARGET_DELAY_VARTRACK]
+
+[TARGET_NO_REGISTER_ALLOCATION]
+.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
+
+ True if register allocation and the passes
+ following it should not be run. Usually true only for virtual assembler
+ targets.
+
+[TARGET_NO_REGISTER_ALLOCATION]
+
+[TARGET_MODE_EMIT]
+.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
+
+ Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
+ :samp:`{hard_reg_live}` is the set of hard registers live at the point where
+ the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
+ to switch from. Sets of a lower numbered entity will be emitted before
+ sets of a higher numbered entity to a mode of the same or lower priority.
+
+[TARGET_MODE_EMIT]
+
+[TARGET_MODE_NEEDED]
+.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
+ to return an integer value not larger than the corresponding element
+ in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
+ must be switched into prior to the execution of :samp:`{insn}`.
+
+[TARGET_MODE_NEEDED]
+
+[TARGET_MODE_AFTER]
+.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
+
+ :samp:`{entity}` is an integer specifying a mode-switched entity.
+ If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
+ switching. It determines the mode that an insn results
+ in (if different from the incoming mode).
+
+[TARGET_MODE_AFTER]
+
+[TARGET_MODE_ENTRY]
+.. function:: int TARGET_MODE_ENTRY (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function entry.
+ If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
+ must be defined.
+
+[TARGET_MODE_ENTRY]
+
+[TARGET_MODE_EXIT]
+.. function:: int TARGET_MODE_EXIT (int entity)
+
+ If this macro is defined, it is evaluated for every :samp:`{entity}` that
+ needs mode switching. It should evaluate to an integer, which is a mode
+ that :samp:`{entity}` is assumed to be switched to at function exit.
+ If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
+ must be defined.
+
+[TARGET_MODE_EXIT]
+
+[TARGET_MODE_PRIORITY]
+.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
+
+ This macro specifies the order in which modes for :samp:`{entity}`
+ are processed. 0 is the highest priority,
+ ``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
+ The value of the macro should be an integer designating a mode
+ for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
+ (:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
+ ``num_modes_for_mode_switching[entity] - 1``.
+
+[TARGET_MODE_PRIORITY]
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+.. function:: bool TARGET_MEMTAG_CAN_TAG_ADDRESSES ()
+
+ True if the backend architecture naturally supports ignoring some region
+ of pointers. This feature means that :option:`-fsanitize=hwaddress` can
+ work.
+
+ At preset, this feature does not support address spaces. It also requires
+ ``Pmode`` to be the same as ``ptr_mode``.
+
+[TARGET_MEMTAG_CAN_TAG_ADDRESSES]
+
+[TARGET_MEMTAG_TAG_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_TAG_SIZE ()
+
+ Return the size of a tag (in bits) for this platform.
+
+ The default returns 8.
+
+[TARGET_MEMTAG_TAG_SIZE]
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+.. function:: uint8_t TARGET_MEMTAG_GRANULE_SIZE ()
+
+ Return the size in real memory that each byte in shadow memory refers to.
+ I.e. if a variable is :samp:`{X}` bytes long in memory, then this hook should
+ return the value :samp:`{Y}` such that the tag in shadow memory spans
+ :samp:`{X}` / :samp:`{Y}` bytes.
+
+ Most variables will need to be aligned to this amount since two variables
+ that are neighbors in memory and share a tag granule would need to share
+ the same tag.
+
+ The default returns 16.
+
+[TARGET_MEMTAG_GRANULE_SIZE]
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+.. function:: rtx TARGET_MEMTAG_INSERT_RANDOM_TAG (rtx untagged, rtx target)
+
+ Return an RTX representing the value of :samp:`{untagged}` but with a
+ (possibly) random tag in it.
+ Put that value into :samp:`{target}` if it is convenient to do so.
+ This function is used to generate a tagged base for the current stack frame.
+
+[TARGET_MEMTAG_INSERT_RANDOM_TAG]
+
+[TARGET_MEMTAG_ADD_TAG]
+.. function:: rtx TARGET_MEMTAG_ADD_TAG (rtx base, poly_int64 addr_offset, uint8_t tag_offset)
+
+ Return an RTX that represents the result of adding :samp:`{addr_offset}` to
+ the address in pointer :samp:`{base}` and :samp:`{tag_offset}` to the tag in pointer
+ :samp:`{base}`.
+ The resulting RTX must either be a valid memory address or be able to get
+ put into an operand with ``force_operand``.
+
+ Unlike other memtag hooks, this must return an expression and not emit any
+ RTL.
+
+[TARGET_MEMTAG_ADD_TAG]
+
+[TARGET_MEMTAG_SET_TAG]
+.. function:: rtx TARGET_MEMTAG_SET_TAG (rtx untagged_base, rtx tag, rtx target)
+
+ Return an RTX representing :samp:`{untagged_base}` but with the tag :samp:`{tag}`.
+ Try and store this in :samp:`{target}` if convenient.
+ :samp:`{untagged_base}` is required to have a zero tag when this hook is called.
+ The default of this hook is to set the top byte of :samp:`{untagged_base}` to
+ :samp:`{tag}`.
+
+[TARGET_MEMTAG_SET_TAG]
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+.. function:: rtx TARGET_MEMTAG_EXTRACT_TAG (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing the tag stored in :samp:`{tagged_pointer}`.
+ Store the result in :samp:`{target}` if it is convenient.
+ The default represents the top byte of the original pointer.
+
+[TARGET_MEMTAG_EXTRACT_TAG]
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+.. function:: rtx TARGET_MEMTAG_UNTAGGED_POINTER (rtx tagged_pointer, rtx target)
+
+ Return an RTX representing :samp:`{tagged_pointer}` with its tag set to zero.
+ Store the result in :samp:`{target}` if convenient.
+ The default clears the top byte of the original pointer.
+
+[TARGET_MEMTAG_UNTAGGED_POINTER]
+
+[TARGET_RUN_TARGET_SELFTESTS]
+.. function:: void TARGET_RUN_TARGET_SELFTESTS (void)
+
+ If selftests are enabled, run any selftests for this target.
+
+[TARGET_RUN_TARGET_SELFTESTS]
+
+[TARGET_GCOV_TYPE_SIZE]
+.. function:: HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+
+ Returns the gcov type size in bits. This type is used for example for
+ counters incremented by profiling and code-coverage events. The default
+ value is 64, if the type size of long long is greater than 32, otherwise the
+ default value is 32. A 64-bit type is recommended to avoid overflows of the
+ counters. If the :option:`-fprofile-update=atomic` is used, then the
+ counters are incremented using atomic operations. Targets not supporting
+ 64-bit atomic operations may override the default value and request a 32-bit
+ type.
+
+[TARGET_GCOV_TYPE_SIZE]
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+.. c:var:: bool TARGET_HAVE_SHADOW_CALL_STACK
+
+ This value is true if the target platform supports
+ :option:`-fsanitize=shadow-call-stack`. The default value is false.
+
+[TARGET_HAVE_SHADOW_CALL_STACK]
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
+
+ Targets may provide a string object type that can be used within
+ and between C, C++ and their respective Objective-C dialects.
+ A string object might, for example, embed encoding and length information.
+ These objects are considered opaque to the compiler and handled as references.
+ An ideal implementation makes the composition of the string object
+ match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
+ allowing efficient interworking between C-only and Objective-C code.
+ If a target implements string objects then this hook should return a
+ reference to such an object constructed from the normal 'C' string
+ representation provided in :samp:`{string}`.
+ At present, the hook is used by Objective-C only, to obtain a
+ common-format string object when the target provides one.
+
+[TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is referenced
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
+
+ Declare that Objective C class :samp:`{classname}` is defined
+ by the current TU.
+
+[TARGET_OBJC_DECLARE_CLASS_DEFINITION]
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
+
+ If a target implements string objects then this hook should return
+ ``true`` if :samp:`{stringref}` is a valid reference to such an object.
+
+[TARGET_STRING_OBJECT_REF_TYPE_P]
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
+
+ If a target implements string objects then this hook should
+ provide a facility to check the function arguments in :samp:`{args_list}`
+ against the format specifiers in :samp:`{format_arg}` where the type of
+ :samp:`{format_arg}` is one recognized as a valid string reference type.
+
+[TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
+
+[TARGET_C_PREINCLUDE]
+.. function:: const char * TARGET_C_PREINCLUDE (void)
+
+ Define this hook to return the name of a header file to be included at
+ the start of all compilations, as if it had been included with
+ ``#include <file>``. If this hook returns ``NULL``, or is
+ not defined, or the header is not found, or if the user specifies
+ :option:`-ffreestanding` or :option:`-nostdinc`, no header is included.
+
+ This hook can be used together with a header provided by the system C
+ library to implement ISO C requirements for certain macros to be
+ predefined that describe properties of the whole implementation rather
+ than just the compiler.
+
+[TARGET_C_PREINCLUDE]
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+.. function:: bool TARGET_CXX_IMPLICIT_EXTERN_C (const char*)
+
+ Define this hook to add target-specific C++ implicit extern C functions.
+ If this function returns true for the name of a file-scope function, that
+ function implicitly gets extern "C" linkage rather than whatever language
+ linkage the declaration would normally have. An example of such function
+ is WinMain on Win32 targets.
+
+[TARGET_CXX_IMPLICIT_EXTERN_C]
+
+[TARGET_OPTION_INIT_STRUCT]
+.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
+
+ Set target-dependent initial values of fields in :samp:`{opts}`.
+
+[TARGET_OPTION_INIT_STRUCT]
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
+
+ Whether this target supports splitting the stack when the options
+ described in :samp:`{opts}` have been passed. This is called
+ after options have been parsed, so the target may reject splitting
+ the stack in some configurations. The default version of this hook
+ returns false. If :samp:`{report}` is true, this function may issue a warning
+ or error; if :samp:`{report}` is false, it must simply return a value
+
+[TARGET_SUPPORTS_SPLIT_STACK]
+
+[TARGET_GET_VALID_OPTION_VALUES]
+.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
+
+ The hook is used for options that have a non-trivial list of
+ possible option values. OPTION_CODE is option code of opt_code
+ enum type. PREFIX is used for bash completion and allows an implementation
+ to return more specific completion based on the prefix. All string values
+ should be allocated from heap memory and consumers should release them.
+ The result will be pruned to cases with PREFIX if not NULL.
+
+[TARGET_GET_VALID_OPTION_VALUES]
+
+[TARGET_COMPUTE_MULTILIB]
+.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
+
+ Some targets like RISC-V might have complicated multilib reuse rules which
+ are hard to implement with the current multilib scheme. This hook allows
+ targets to override the result from the built-in multilib mechanism.
+ :samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
+ :samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
+ multi-lib mechanism;
+ :samp:`{multilib_defaults}` is the default options list for multi-lib;
+ :samp:`{multilib_select}` is the string containing the list of supported
+ multi-libs, and the option checking list.
+ :samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
+ are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
+ and :samp:`{MULTILIB_REUSE}`.
+ The default definition does nothing but return :samp:`{multilib_dir}` directly.
+
+[TARGET_COMPUTE_MULTILIB]
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
+
+ True if :samp:`..` components should always be removed from directory names
+ computed relative to GCC's internal directories, false (default) if such
+ components should be preserved and directory names containing them passed
+ to other tools such as the linker.
+
+[TARGET_ALWAYS_STRIP_DOTDOT]
+
+[TARGET_D_CPU_VERSIONS]
+.. function:: void TARGET_D_CPU_VERSIONS (void)
+
+ Declare all environmental version identifiers relating to the target CPU
+ using the function ``builtin_version``, which takes a string representing
+ the name of the version. Version identifiers predefined by this hook apply
+ to all modules that are being compiled and imported.
+
+[TARGET_D_CPU_VERSIONS]
+
+[TARGET_D_OS_VERSIONS]
+.. function:: void TARGET_D_OS_VERSIONS (void)
+
+ Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
+ relating to the target operating system.
+
+[TARGET_D_OS_VERSIONS]
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
+
+ Register all target information keys relating to the target CPU using the
+ function ``d_add_target_info_handlers``, which takes a
+ :samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
+ added by this hook are made available at compile time by the
+ ``__traits(getTargetInfo)`` extension, the result is an expression
+ describing the requested target information.
+
+[TARGET_D_REGISTER_CPU_TARGET_INFO]
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
+
+ Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
+ the target operating system.
+
+[TARGET_D_REGISTER_OS_TARGET_INFO]
+
+[TARGET_D_MINFO_SECTION]
+.. c:var:: const char * TARGET_D_MINFO_SECTION
+
+ Contains the name of the section in which module info references should be
+ placed. By default, the compiler puts all module info symbols in the
+ ``"minfo"`` section. Define this macro to override the string if a
+ different section name should be used. This section is expected to be
+ bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
+ ``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
+ the section, so that the runtime library can collect all modules for each
+ loaded shared library and executable. Setting the value to ``NULL``
+ disables the use of sections for storing module info altogether.
+
+[TARGET_D_MINFO_SECTION]
+
+[TARGET_D_MINFO_SECTION_START]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_START
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the start address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_START]
+
+[TARGET_D_MINFO_SECTION_END]
+.. c:var:: const char * TARGET_D_MINFO_SECTION_END
+
+ If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
+ as the name of the symbol indicating the end address of the module info
+ section
+
+[TARGET_D_MINFO_SECTION_END]
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
+
+ Returns ``true`` if the target supports the stdcall calling convention.
+ The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
+ attribute should be applied to functions with ``extern(System)`` linkage,
+ and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
+ ``extern(Windows)`` linkage.
+
+[TARGET_D_HAS_STDCALL_CONVENTION]
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
+
+ This flag is true if instantiated functions and variables are always COMDAT
+ if they have external linkage. If this flag is false, then instantiated
+ decls will be emitted as weak symbols. The default is ``false``.
+
+[TARGET_D_TEMPLATES_ALWAYS_COMDAT]
+
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-11-08 14:42 UTC | newest]
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