https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94400
Bug ID: 94400
Summary: 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than
GCC 9
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jamborm at gcc dot gnu.org
CC: hubicka at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux
Target: x86_64-linux
When compiled with -O2 -march=native and run on an AMD Zen2 CPU,
531.deepsjeng_r runs about 7% slower. This can be bisected to a
single commit:
commit a9a4edf0e71bbac9f1b5dcecdcf9250111d16889
Author: Jan Hubicka <hubi...@ucw.cz>
Date: Sat Nov 30 22:25:24 2019 +0100
Update max_bb_count in execute_fixup_cfg
* tree-cfg.c (execute_fixup_cfg): Update also max_bb_count when
scaling happen.
From-SVN: r278879
Surprisingly, I cannot see a similar problem on an Intel Cascade Lake
server CPU, but I have confirmed the above on two different Rome
systems (one running SLES, one openSUSE Tumbleweed).
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)
