https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126055
Bug ID: 126055
Summary: [17 Regression] 10% slowdown of perlbench_r on AMD
Zen5 since r17-1927-gb64fc298a3538c
Product: gcc
Version: 17.0
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=1285.327.0
there was a 10% slowdown of perlbench_r SPEC CPU 2017 benchmark on AMD Zen5
when compiled with -Ofast -march=native -flto PGO (-fprofile-use).
I've bisected this to r17-1927-gb64fc298a3538c
commit b64fc298a3538c3d7d85ca05fef822acba23e4a1
Author: H.J. Lu <[email protected]>
AuthorDate: Wed Jun 17 17:32:21 2026 +0800
Commit: H.J. Lu <[email protected]>
CommitDate: Sat Jun 27 05:06:55 2026 +0800
x86-64: Expand bounded memset and memcpy like memmove
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)
