https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123051
Bug ID: 123051
Summary: [16 Regression] 25-30% slowdown of 470.lbm on Zen5
since r16-5902-g1da0e5c1405e87
Product: gcc
Version: 16.0
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: rguenth 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=1284.240.0
there was a 25-30% exec time slowdown of the 470.lbm SPEC 2006
benchmark when compiled with -Ofast -march=native -mtune=native -lto on an Zen5
machine. I bisected it to r16-5902-g1da0e5c1405e87.
commit 1da0e5c1405e87e9f2a11ed358b40dff21085657
Author: Richard Biener <[email protected]>
Date: Thu Aug 21 13:46:06 2025 +0200
Move even/odd validity check from supportable_widening_operation to caller
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)
