[Bug target/115463] New: 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[Bug target/115463] New: 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[jamborm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

            Bug ID: 115463
           Summary: 526.blender_r regressed 5% on Zen2 with -Ofast -flto
                    -march=native since r15-1058-gc989e59fc99d99
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jamborm at gcc dot gnu.org
                CC: hongyuw at gcc dot gnu.org
            Blocks: 26163
  Target Milestone: ---

The run-time of benchmark 526.blender_r from SPEC INTrate 2017 has
regressed 5.3% on Zen2-based CPUs when compiled with -Ofast -flto
-march-mnative since r15-1058-gc989e59fc99d99 (Hongyu Wang: [APX CCMP]
Support APX CCMP).  I was not expecting this patch to cause any
changes in code generated for non-APX CPUs but I have double checked.

The regression can be seen/tracked at
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=287.487.0


There are also smaller regressions that happened around the same time:

- zen2 -Ofast -flto -fprofile-use -march=native: 3%
  https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=286.487.0

- skylake -Ofast -flto -march=native: 4%
  https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=801.487.0

- skylake -Ofast -flto -fprofile-use -march=native: 3%
  https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=792.487.0

- zen3 -Ofast -flto -march=native: 2%
  https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=475.487.0


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)

[Bug target/115463] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |115370

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Most likely similar to PR 115370. Yes enabling ccmp for x86_64's APX
unfortunately enables it for all of x86_64 due to the way ccmp was originally
designed (thinking it was enabled for the whole target or not).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115370
[Bug 115370] [15 regression] gcc.target/i386/pr77881.c FAIL

[Bug target/115463] [15 regression] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-*-*
   Target Milestone|---                         |15.0
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=115370
            Version|14.0                        |15.0

[Bug target/115463] [15 regression] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Hongyu Wang <hongyuw@gcc.gnu.org>:

https://gcc.gnu.org/g:83a765768510d1f329887116757d6818d7846717

commit r15-1293-g83a765768510d1f329887116757d6818d7846717
Author: Hongyu Wang <hongyu.wang@intel.com>
Date:   Thu Jun 13 00:18:32 2024 +0800

    [APX CCMP] Add targetm.have_ccmp hook [PR115370]

    In cfgexpand, there is an optimization for branch which tests
    targetm.gen_ccmp_first == NULL. However for target like x86-64, the
    hook was implemented but it does not indicate that ccmp was enabled.
    Add a new target hook TARGET_HAVE_CCMP and replace the middle-end
    check for the existance of gen_ccmp_first to avoid misoptimization.

    gcc/ChangeLog:

            PR target/115370
            PR target/115463
            * target.def (have_ccmp): New target hook.
            * targhooks.cc (default_have_ccmp): New function.
            * targhooks.h (default_have_ccmp): New prototype.
            * doc/tm.texi.in: Add TARGET_HAVE_CCMP.
            * doc/tm.texi: Regenerate.
            * cfgexpand.cc (expand_gimple_cond): Call targetm.have_ccmp
            instead of checking if targetm.gen_ccmp_first exists.
            * expr.cc (expand_expr_real_gassign): Likewise.
            * config/i386/i386.cc (ix86_have_ccmp): New target hook to
            check if APX_CCMP enabled.
            (TARGET_HAVE_CCMP): Define.

[Bug target/115463] [15 regression] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[hongyuw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

--- Comment #3 from Hongyu Wang <hongyuw at gcc dot gnu.org> ---
Should be fixed, but will wait for the confirm of SPEC result on znver/skylake.

[Bug target/115463] [15 regression] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[hongyuw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463
Bug 115463 depends on bug 115370, which changed state.

Bug 115370 Summary: [15 regression] gcc.target/i386/pr77881.c FAIL
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115370

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

[Bug target/115463] [15 regression] 526.blender_r regressed 5% on Zen2 with -Ofast -flto -march=native since r15-1058-gc989e59fc99d99

[liuhongt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115463

Hongtao Liu <liuhongt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |liuhongt at gcc dot gnu.org

--- Comment #4 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
should be fixed by r15-1293-g83a765768510d1f329887116757d6818d7846717.