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From: Xi Ruoyao <xry111@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-4849] LoongArch: Use explicit relocs for GOT access when -mexplicit-relocs=auto and LTO during a final lin Date: Mon, 23 Oct 2023 07:31:25 +0000 (GMT) [thread overview] Message-ID: <20231023073125.B2175385828D@sourceware.org> (raw) https://gcc.gnu.org/g:8811630df88bccfab232f8ab7da4bb43b70fa9de commit r14-4849-g8811630df88bccfab232f8ab7da4bb43b70fa9de Author: Xi Ruoyao <xry111@xry111.site> Date: Sat Sep 30 18:46:28 2023 +0800 LoongArch: Use explicit relocs for GOT access when -mexplicit-relocs=auto and LTO during a final link with linker plugin If we are performing LTO for a final link and linker plugin is enabled, then we are sure any GOT access may resolve to a symbol out of the link unit (otherwise the linker plugin will tell us the symbol should be resolved locally and we'll use PC-relative access instead). Produce machine instructions with explicit relocs instead of la.global for better scheduling. gcc/ChangeLog: * config/loongarch/loongarch-protos.h (loongarch_explicit_relocs_p): Declare new function. * config/loongarch/loongarch.cc (loongarch_explicit_relocs_p): Implement. (loongarch_symbol_insns): Call loongarch_explicit_relocs_p for SYMBOL_GOT_DISP, instead of using TARGET_EXPLICIT_RELOCS. (loongarch_split_symbol): Call loongarch_explicit_relocs_p for deciding if return early, instead of using TARGET_EXPLICIT_RELOCS. (loongarch_output_move): CAll loongarch_explicit_relocs_p instead of using TARGET_EXPLICIT_RELOCS. * config/loongarch/loongarch.md (*low<mode>): Remove TARGET_EXPLICIT_RELOCS from insn condition. (@ld_from_got<mode>): Likewise. * config/loongarch/predicates.md (move_operand): Call loongarch_explicit_relocs_p instead of using TARGET_EXPLICIT_RELOCS. gcc/testsuite/ChangeLog: * gcc.target/loongarch/explicit-relocs-auto-lto.c: New test. Diff: --- gcc/config/loongarch/loongarch-protos.h | 1 + gcc/config/loongarch/loongarch.cc | 34 +++++++++++++++++----- gcc/config/loongarch/loongarch.md | 4 +-- gcc/config/loongarch/predicates.md | 8 ++--- .../loongarch/explicit-relocs-auto-lto.c | 26 +++++++++++++++++ 5 files changed, 59 insertions(+), 14 deletions(-) diff --git a/gcc/config/loongarch/loongarch-protos.h b/gcc/config/loongarch/loongarch-protos.h index 72ae9918b096..cb8fc36b0863 100644 --- a/gcc/config/loongarch/loongarch-protos.h +++ b/gcc/config/loongarch/loongarch-protos.h @@ -220,4 +220,5 @@ extern rtx loongarch_gen_const_int_vector_shuffle (machine_mode, int); extern tree loongarch_build_builtin_va_list (void); extern rtx loongarch_build_signbit_mask (machine_mode, bool, bool); +extern bool loongarch_explicit_relocs_p (enum loongarch_symbol_type); #endif /* ! GCC_LOONGARCH_PROTOS_H */ diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc index 5df8b12ed921..c12d77ea1449 100644 --- a/gcc/config/loongarch/loongarch.cc +++ b/gcc/config/loongarch/loongarch.cc @@ -1925,6 +1925,29 @@ loongarch_symbolic_constant_p (rtx x, enum loongarch_symbol_type *symbol_type) gcc_unreachable (); } +/* If -mexplicit-relocs=auto, we use machine operations with reloc hints + for cases where the linker is unable to relax so we can schedule the + machine operations, otherwise use an assembler pseudo-op so the + assembler will generate R_LARCH_RELAX. */ + +bool +loongarch_explicit_relocs_p (enum loongarch_symbol_type type) +{ + if (la_opt_explicit_relocs != EXPLICIT_RELOCS_AUTO) + return la_opt_explicit_relocs == EXPLICIT_RELOCS_ALWAYS; + + /* If we are performing LTO for a final link, and we have the linker + plugin so we know the resolution of the symbols, then all GOT + references are binding to external symbols or preemptable symbols. + So the linker cannot relax them. */ + return (in_lto_p + && !flag_incremental_link + && HAVE_LTO_PLUGIN == 2 + && (!global_options_set.x_flag_use_linker_plugin + || global_options.x_flag_use_linker_plugin) + && type == SYMBOL_GOT_DISP); +} + /* Returns the number of instructions necessary to reference a symbol. */ static int @@ -1940,7 +1963,7 @@ loongarch_symbol_insns (enum loongarch_symbol_type type, machine_mode mode) case SYMBOL_GOT_DISP: /* The constant will have to be loaded from the GOT before it is used in an address. */ - if (!TARGET_EXPLICIT_RELOCS && mode != MAX_MACHINE_MODE) + if (!loongarch_explicit_relocs_p (type) && mode != MAX_MACHINE_MODE) return 0; return 3; @@ -3038,7 +3061,7 @@ loongarch_symbol_extreme_p (enum loongarch_symbol_type type) If so, and if LOW_OUT is nonnull, emit the high part and store the low part in *LOW_OUT. Leave *LOW_OUT unchanged otherwise. - Return false if build with '-mno-explicit-relocs'. + Return false if build with '-mexplicit-relocs=none'. TEMP is as for loongarch_force_temporary and is used to load the high part into a register. @@ -3052,12 +3075,9 @@ loongarch_split_symbol (rtx temp, rtx addr, machine_mode mode, rtx *low_out) { enum loongarch_symbol_type symbol_type; - /* If build with '-mno-explicit-relocs', don't split symbol. */ - if (!TARGET_EXPLICIT_RELOCS) - return false; - if ((GET_CODE (addr) == HIGH && mode == MAX_MACHINE_MODE) || !loongarch_symbolic_constant_p (addr, &symbol_type) + || !loongarch_explicit_relocs_p (symbol_type) || loongarch_symbol_insns (symbol_type, mode) == 0 || !loongarch_split_symbol_type (symbol_type)) return false; @@ -4797,7 +4817,7 @@ loongarch_output_move (rtx dest, rtx src) } } - if (!TARGET_EXPLICIT_RELOCS + if (!loongarch_explicit_relocs_p (loongarch_classify_symbol (src)) && dest_code == REG && symbolic_operand (src, VOIDmode)) { if (loongarch_classify_symbol (src) == SYMBOL_PCREL) diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md index 365b4127e31e..bec73f1bc916 100644 --- a/gcc/config/loongarch/loongarch.md +++ b/gcc/config/loongarch/loongarch.md @@ -2247,7 +2247,7 @@ [(set (match_operand:P 0 "register_operand" "=r") (lo_sum:P (match_operand:P 1 "register_operand" " r") (match_operand:P 2 "symbolic_operand" "")))] - "TARGET_EXPLICIT_RELOCS" + "" "addi.<d>\t%0,%1,%L2" [(set_attr "type" "arith") (set_attr "mode" "<MODE>")]) @@ -2275,7 +2275,7 @@ (match_operand:P 1 "register_operand" "r") (match_operand:P 2 "symbolic_operand")))] UNSPEC_LOAD_FROM_GOT))] - "TARGET_EXPLICIT_RELOCS" + "" "ld.<d>\t%0,%1,%L2" [(set_attr "type" "move")] ) diff --git a/gcc/config/loongarch/predicates.md b/gcc/config/loongarch/predicates.md index 499518b82ba6..359878f5bcf2 100644 --- a/gcc/config/loongarch/predicates.md +++ b/gcc/config/loongarch/predicates.md @@ -541,16 +541,14 @@ case SYMBOL_REF: case LABEL_REF: return (loongarch_symbolic_constant_p (op, &symbol_type) - && (!TARGET_EXPLICIT_RELOCS + && (!loongarch_explicit_relocs_p (symbol_type) || !loongarch_split_symbol_type (symbol_type))); case HIGH: - /* '-mno-explicit-relocs' don't generate high/low pairs. */ - if (!TARGET_EXPLICIT_RELOCS) - return false; - op = XEXP (op, 0); + return (loongarch_symbolic_constant_p (op, &symbol_type) + && loongarch_explicit_relocs_p (symbol_type) && loongarch_split_symbol_type (symbol_type)); default: diff --git a/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-lto.c b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-lto.c new file mode 100644 index 000000000000..f53b54689242 --- /dev/null +++ b/gcc/testsuite/gcc.target/loongarch/explicit-relocs-auto-lto.c @@ -0,0 +1,26 @@ +/* { dg-do link } */ +/* { dg-require-effective-target lto } */ +/* { dg-require-linker-plugin "" } */ +/* { dg-options "-fpic -shared -O2 --save-temps -mexplicit-relocs=auto -flto -fuse-linker-plugin -flto-partition=one" } */ + +int pcrel __attribute__ ((visibility ("hidden"))); +int got __attribute__ ((visibility ("default"))); + +int +*addr_pcrel (void) +{ + return &pcrel; +} + +int +*addr_got (void) +{ + return &got; +} + +/* With linker plugin we should use la.local (it can be relaxed to pcaddi), + but not la.global (we are pretty sure the linker cannot relax la.global + got). */ +/* { dg-final { scan-lto-assembler "la.local.*pcrel" } } */ +/* { dg-final { scan-lto-assembler "pcalau12i.*%got_pc_hi20\\\(got\\\)" } } */ +/* { dg-final { scan-lto-assembler "ld.*%got_pc_lo12\\\(got\\\)" } } */
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