https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121994
Bug ID: 121994
Summary: [16 Regression] 15% slowdown of 538.imagick_r on AMD
Zen2 since r16-3396-g9823624395a946
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: liuhongt at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux
Target: x86_64-linux
As seen here
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=287.507.0
there was a 15% exec time slowdown of the 538.imagick_r SPEC 2017
benchmark when compiled with -Ofast -march=native -flto on an AMD Zen2
machine. I bisected it to r16-3396-g9823624395a946.
commit 9823624395a946bb08a74e5aa4fb5d8bcebacfdf
Author: liuhongt <[email protected]>
Date: Mon Jul 28 18:06:06 2025 -0700
Enable unroll in the vectorizer when there's reduction for
FMA/DOT_PROD_EXPR/SAD_EXPR
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)
