https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113600
Bug ID: 113600
Summary: 525.x264_r run-time regresses by 8% with PGO -Ofast
-march=znver4
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: liuhongt at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux-gnu
Target: x86_64-linux-gnu
With profile-feedback, -Ofast and -march=native on an AMD Zen 4, there is a
recent 8% regression:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=979.377.0&plot.1=966.377.0&;
With both PGO and LTO, the situation is similar (6%):
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=977.377.0&plot.1=958.377.0&;
On a Zen3 machine, there is a 2% bump around the same time:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=900.377.0&plot.1=473.377.0&;
I have bisected the (non-LTO) Zen 4 case to commit r14-5603-g2b59e2b4dff421:
2b59e2b4dff42118fe3a505f07b9a6aa4cf53bdf is the first bad commit
commit 2b59e2b4dff42118fe3a505f07b9a6aa4cf53bdf
Author: liuhongt <hongtao....@intel.com>
Date: Thu Nov 16 18:38:39 2023 +0800
Support reduc_{plus,xor,and,ior}_scal_m for vector integer mode.
BB vectorizer relies on the backend support of
.REDUC_{PLUS,IOR,XOR,AND} to vectorize reduction.
gcc/ChangeLog:
PR target/112325
* config/i386/sse.md (reduc_<code>_scal_<mode>): New expander.
(REDUC_ANY_LOGIC_MODE): New iterator.
(REDUC_PLUS_MODE): Extend to VxHI/SI/DImode.
(REDUC_SSE_PLUS_MODE): Ditto.
gcc/testsuite/ChangeLog:
* gcc.target/i386/pr112325-1.c: New test.
* gcc.target/i386/pr112325-2.c: New test.
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)
