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* [Bug target/94400] New: 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9
@ 2020-03-30 10:04 jamborm at gcc dot gnu.org
2020-03-30 10:10 ` [Bug target/94400] " marxin at gcc dot gnu.org
2021-02-04 16:47 ` jamborm at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: jamborm at gcc dot gnu.org @ 2020-03-30 10:04 UTC (permalink / raw)
To: gcc-bugs
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 <hubicka@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)
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug target/94400] 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9 2020-03-30 10:04 [Bug target/94400] New: 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9 jamborm at gcc dot gnu.org @ 2020-03-30 10:10 ` marxin at gcc dot gnu.org 2021-02-04 16:47 ` jamborm at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: marxin at gcc dot gnu.org @ 2020-03-30 10:10 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94400 Martin Liška <marxin at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 CC| |marxin at gcc dot gnu.org Last reconfirmed| |2020-03-30 Status|UNCONFIRMED |NEW --- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> --- I can confirm on LNT znver2 machine, but the bisection points to a different commit: https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=324.387.0&plot.1=311.387.0&plot.2=348.387.0&plot.3=280.387.0&plot.4=297.387.0& while LNT znver1 machine is not affected and the speed is similar to GCC 9: https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=145.387.0&plot.1=49.387.0&plot.2=79.387.0&plot.3=259.387.0&plot.4=29.387.0& ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/94400] 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9 2020-03-30 10:04 [Bug target/94400] New: 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9 jamborm at gcc dot gnu.org 2020-03-30 10:10 ` [Bug target/94400] " marxin at gcc dot gnu.org @ 2021-02-04 16:47 ` jamborm at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: jamborm at gcc dot gnu.org @ 2021-02-04 16:47 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94400 Martin Jambor <jamborm at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #2 from Martin Jambor <jamborm at gcc dot gnu.org> --- The regression dropped to 1.9% according to my own measurements which also match LNT (linked above). It is peculiar to an unusual option combination, specific to Zen2 (I cannot see it on Zen3 or CascadeLake) and so I think it is unreasonable to expect that anybody will actually want to work on it. And the PR really is mostly fixed, so let me close it as such. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-02-04 16:47 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-03-30 10:04 [Bug target/94400] New: 531.deepsjeng_r is 7% slower at -O2 -march=znver2 than GCC 9 jamborm at gcc dot gnu.org 2020-03-30 10:10 ` [Bug target/94400] " marxin at gcc dot gnu.org 2021-02-04 16:47 ` jamborm at gcc dot gnu.org
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