https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121447
Bug ID: 121447
Summary: [16 Regression] ~20% slowdown of 470.lbm since
r16-1644-gaba3b9d3a48a07 on AMD Zen5
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: pheeck at gcc dot gnu.org
CC: hjl at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: x86_64-pc-linux-gnu
As seen here
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=1283.240.0
r16-1644-gaba3b9d3a48a07 slowed down the 470.lbm SPEC 2006 benchmark by ~20%
when compiled with -Ofast -march=native -flto -fprofile-use on AMD Zen5.
I've already mentioned this slowdown in pr120941 comment 8. Apparently this is
a separate problem, since the fix for pr120941 didn't help with this.
I'll eventually try to find out what is causing the slowdown and extract a
testcase. I expect analysis will be more difficult since PGO is involved this
time.
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)
