[i386] adjust flag_omit_frame_pointer in a single function [PR113719] (was: Re: [PATCH] [i386] restore recompute to override opts after change [PR113719])

[Hongtao Liu]

On Thu, Jul 11, 2024 at 9:07 PM Alexandre Oliva <oliva@adacore.com> wrote:
>
> On Jul  4, 2024, Alexandre Oliva <oliva@adacore.com> wrote:
>
> > On Jul  3, 2024, Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> wrote:
>
> > Hmm, I wonder if leaf frame pointer has to do with that.
>
> It did, in a way.
>
> ----
>
> The first two patches for PR113719 have each regressed
> gcc.dg/ipa/iinline-attr.c on a different target.  The reason for this
> instability is that there are competing flag_omit_frame_pointer
> overriders on x86:
>
> - ix86_recompute_optlev_based_flags computes and sets a
>   -f[no-]omit-frame-pointer default depending on
>   USE_IX86_FRAME_POINTER and, in 32-bit mode, optimize_size
>
> - ix86_option_override_internal enables flag_omit_frame_pointer for
>   -momit-leaf-frame-pointer to take effect
>
> ix86_option_override[_internal] calls
> ix86_recompute_optlev_based_flags before setting
> flag_omit_frame_pointer.  It is called during global process_options.
>
> But ix86_recompute_optlev_based_flags is also called by
> parse_optimize_options, during attribute processing, and at that
> point, ix86_option_override is not called, so the final overrider for
> global options is not applied to the optimize attributes.  If they
> differ, the testcase fails.
>
> In order to fix this, we need to process all overriders of this option
> whenever we process any of them.  Since this setting is affected by
> optimization options, it makes sense to compute it in
> parse_optimize_options, rather than in process_options.
>
> Regstrapped on x86_64-linux-gnu.  Also verified that the regression is
> cured with a i686-solaris cross compiler.  Ok to install?
Ok. thanks.
>
>
> for  gcc/ChangeLog
>
>         PR target/113719
>         * config/i386/i386-options.cc (ix86_option_override_internal):
>         Move flag_omit_frame_pointer final overrider...
>         (ix86_recompute_optlev_based_flags): ... here.
> ---
>  gcc/config/i386/i386-options.cc |   12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
> index 5824c0cb072eb..059ef3ae6ad44 100644
> --- a/gcc/config/i386/i386-options.cc
> +++ b/gcc/config/i386/i386-options.cc
> @@ -1911,6 +1911,12 @@ ix86_recompute_optlev_based_flags (struct gcc_options *opts,
>             opts->x_flag_pcc_struct_return = DEFAULT_PCC_STRUCT_RETURN;
>         }
>      }
> +
> +  /* Keep nonleaf frame pointers.  */
> +  if (opts->x_flag_omit_frame_pointer)
> +    opts->x_target_flags &= ~MASK_OMIT_LEAF_FRAME_POINTER;
> +  else if (TARGET_OMIT_LEAF_FRAME_POINTER_P (opts->x_target_flags))
> +    opts->x_flag_omit_frame_pointer = 1;
>  }
>
>  /* Implement part of TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE hook.  */
> @@ -2590,12 +2596,6 @@ ix86_option_override_internal (bool main_args_p,
>          opts->x_target_flags |= MASK_NO_RED_ZONE;
>      }
>
> -  /* Keep nonleaf frame pointers.  */
> -  if (opts->x_flag_omit_frame_pointer)
> -    opts->x_target_flags &= ~MASK_OMIT_LEAF_FRAME_POINTER;
> -  else if (TARGET_OMIT_LEAF_FRAME_POINTER_P (opts->x_target_flags))
> -    opts->x_flag_omit_frame_pointer = 1;
> -
>    /* If we're doing fast math, we don't care about comparison order
>       wrt NaNs.  This lets us use a shorter comparison sequence.  */
>    if (opts->x_flag_finite_math_only)
>
>
> --
> Alexandre Oliva, happy hacker            https://FSFLA.org/blogs/lxo/
>    Free Software Activist                   GNU Toolchain Engineer
> More tolerance and less prejudice are key for inclusion and diversity
> Excluding neuro-others for not behaving ""normal"" is *not* inclusive



-- 
BR,
Hongtao