On Wed, Feb 5, 2020 at 2:51 PM H.J. Lu wrote: > > On Wed, Feb 5, 2020 at 2:37 PM Marek Polacek wrote: > > > > On Wed, Feb 05, 2020 at 02:24:48PM -0800, H.J. Lu wrote: > > > On Wed, Feb 5, 2020 at 12:20 PM H.J. Lu wrote: > > > > > > > > On Wed, Feb 5, 2020 at 9:00 AM Richard Sandiford > > > > wrote: > > > > > > > > > > "H.J. Lu" writes: > > > > > > Currently patchable area is at the wrong place. > > > > > > > > > > Agreed :-) > > > > > > > > > > > It is placed immediately > > > > > > after function label and before .cfi_startproc. A backend should be able > > > > > > to add a pseudo patchable area instruction durectly into RTL. This patch > > > > > > adds patch_area_size and patch_area_entry to cfun so that the patchable > > > > > > area info is available in RTL passes. > > > > > > > > > > It might be better to add it to crtl, since it should only be needed > > > > > during rtl generation. > > > > > > > > > > > It also limits patch_area_size and patch_area_entry to 65535, which is > > > > > > a reasonable maximum size for patchable area. > > > > > > > > > > > > gcc/ > > > > > > > > > > > > PR target/93492 > > > > > > * function.c (expand_function_start): Set cfun->patch_area_size > > > > > > and cfun->patch_area_entry. > > > > > > * function.h (function): Add patch_area_size and patch_area_entry. > > > > > > * opts.c (common_handle_option): Limit > > > > > > function_entry_patch_area_size and function_entry_patch_area_start > > > > > > to USHRT_MAX. Fix a typo in error message. > > > > > > * varasm.c (assemble_start_function): Use cfun->patch_area_size > > > > > > and cfun->patch_area_entry. > > > > > > * doc/invoke.texi: Document the maximum value for > > > > > > -fpatchable-function-entry. > > > > > > > > > > > > gcc/testsuite/ > > > > > > > > > > > > PR target/93492 > > > > > > * c-c++-common/patchable_function_entry-error-1.c: New test. > > > > > > * c-c++-common/patchable_function_entry-error-2.c: Likewise. > > > > > > * c-c++-common/patchable_function_entry-error-3.c: Likewise. > > > > > > --- > > > > > > gcc/doc/invoke.texi | 1 + > > > > > > gcc/function.c | 35 +++++++++++++++++++ > > > > > > gcc/function.h | 6 ++++ > > > > > > gcc/opts.c | 4 ++- > > > > > > .../patchable_function_entry-error-1.c | 9 +++++ > > > > > > .../patchable_function_entry-error-2.c | 9 +++++ > > > > > > .../patchable_function_entry-error-3.c | 20 +++++++++++ > > > > > > gcc/varasm.c | 30 ++-------------- > > > > > > 8 files changed, 85 insertions(+), 29 deletions(-) > > > > > > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c > > > > > > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c > > > > > > create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c > > > > > > > > > > > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > > > > > > index 35b341e759f..dd4835199b0 100644 > > > > > > --- a/gcc/doc/invoke.texi > > > > > > +++ b/gcc/doc/invoke.texi > > > > > > @@ -13966,6 +13966,7 @@ If @code{N=0}, no pad location is recorded. > > > > > > The NOP instructions are inserted at---and maybe before, depending on > > > > > > @var{M}---the function entry address, even before the prologue. > > > > > > > > > > > > +The maximum value of @var{N} and @var{M} is 65535. > > > > > > @end table > > > > > > > > > > > > > > > > > > diff --git a/gcc/function.c b/gcc/function.c > > > > > > index d8008f60422..badbf538eec 100644 > > > > > > --- a/gcc/function.c > > > > > > +++ b/gcc/function.c > > > > > > @@ -5202,6 +5202,41 @@ expand_function_start (tree subr) > > > > > > /* If we are doing generic stack checking, the probe should go here. */ > > > > > > if (flag_stack_check == GENERIC_STACK_CHECK) > > > > > > stack_check_probe_note = emit_note (NOTE_INSN_DELETED); > > > > > > + > > > > > > + unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size; > > > > > > + unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start; > > > > > > + > > > > > > + tree patchable_function_entry_attr > > > > > > + = lookup_attribute ("patchable_function_entry", > > > > > > + DECL_ATTRIBUTES (cfun->decl)); > > > > > > + if (patchable_function_entry_attr) > > > > > > + { > > > > > > + tree pp_val = TREE_VALUE (patchable_function_entry_attr); > > > > > > + tree patchable_function_entry_value1 = TREE_VALUE (pp_val); > > > > > > + > > > > > > + patch_area_size = tree_to_uhwi (patchable_function_entry_value1); > > > > > > + patch_area_entry = 0; > > > > > > + if (TREE_CHAIN (pp_val) != NULL_TREE) > > > > > > + { > > > > > > + tree patchable_function_entry_value2 > > > > > > + = TREE_VALUE (TREE_CHAIN (pp_val)); > > > > > > + patch_area_entry = tree_to_uhwi (patchable_function_entry_value2); > > > > > > + } > > > > > > + if (patch_area_size > USHRT_MAX || patch_area_size > USHRT_MAX) > > > > > > + error ("invalid values for % attribute"); > > > > > > > > > > This should probably go in handle_patchable_function_entry_attribute > > > > > instead. It doesn't look like we have a clear policy about whether > > > > > errors or warnings are right for unrecognised arguments to known > > > > > attribute names, but handle_patchable_function_entry_attribute reports > > > > > an OPT_Wattributes warning for arguments that aren't integers. Doing the > > > > > same for out-of-range integers would be more consistent and means that > > > > > we wouldn't break existing code if we relaxed/changed the rules in future. > > > > > > > > Like this? OK for master if there is no regression? > > > > > > > > > > There is a small problem. Warnings from C and C++ frond-ends are different: > > > > > > [hjl@gnu-skx-1 gcc]$ cat x.c > > > void > > > __attribute__((patchable_function_entry(65536))) > > > foo1 (void) > > > { /* { dg-warning "'patchable_function_entry' attribute argument > > > '65536' is out of range" } */ > > > } > > > [hjl@gnu-skx-1 gcc]$ ./xgcc -B./ -S x.c > > > x.c:4:1: warning: ‘patchable_function_entry’ attribute argument > > > ‘65536’ is out of range (> 65535) [-Wattributes] > > > 4 | { /* { dg-warning "'patchable_function_entry' attribute > > > argument '65536' is out of range" } */ > > > | ^ > > > [hjl@gnu-skx-1 gcc]$ ./xg++ -B./ -S x.c > > > x.c:3:11: warning: ‘patchable_function_entry’ attribute argument > > > ‘65536’ is out of range (> 65535) [-Wattributes] > > > 3 | foo1 (void) > > > | ^ > > > [hjl@gnu-skx-1 gcc]$ > > > > > > C warns at line 4 and C++ warns at line 3. Do I need separate tests > > > for C and C++? > > > > I think better would be > > > > /* { dg-error "foo" "" { target c } } */ > > /* { dg-error "bar" "" { target c++ } .-1 } */ > > > > Marek > > > > It worked. Here is the patch with updated tests. There are no regressions on Linux/x86-64. OK for master? Thanks. -- H.J.