https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127402
Bug ID: 127402
Summary: [17 Regression] 7% slowdown of mcf on Zen5 since
r17-4133-g230d950810f378
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jmelcr at gcc dot gnu.org
CC: pinskia at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-suse-linux
Target: x86_64-suse-linux
Build: x86_64-suse-linux
I am seeing a 7% slowdown of SPEC 2006 mcf with -O2 -march=x86-64-v3 -g
-flto=128 on a Zen5 machine:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1240.60.0
which is a regression against GCC 16
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1311.60.0&plot.1=1344.60.0&plot.2=1541.60.0&plot.3=1240.60.0&;
The slowdown bisects to commit r17-4133-g230d950810f378:
commit 230d950810f378a16c47ab981e0b9cf88b700622
Author: Andrea Pinski <[email protected]>
Date: Tue Aug 25 13:28:49 2026 -0700
phiopt/cselim: Support constants for cond_store_replacement_limited
[PR127052]
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2026, 2k17, 2k and 2k6 and
95)
