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* [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
@ 2024-02-08 16:37 jamborm at gcc dot gnu.org
2024-02-09 0:55 ` [Bug tree-optimization/113833] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: jamborm at gcc dot gnu.org @ 2024-02-08 16:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
Bug ID: 113833
Summary: 435.gromacs fails verification on with -Ofast
-march={cascadelake,icelake-server} and PGO after
r14-7272-g57f611604e8bab
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jamborm at gcc dot gnu.org
CC: fxue at os dot amperecomputing.com
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux
Target: x86_64-linux
After r14-7272-g57f611604e8bab (Feng Xue: Do not count unused scalar
use when marking STMT_VINFO_LIVE_P [PR113091]), our runs of SPEC 2006
CPU benchmark 435.gromacs on Icelake-server CPU compiled with -Ofast
-march=native and PGO (with and without LTO) started failing with
miscompare error:
0002: 3.07684e+02
3.03476e+02
^
I subsequently verified the failure on an Intel CascadeLake and
bisected it to the aforementioned commit. We don't see it on our AMD
or Ampere testers (using -march=native).
I guess the miscomparison error may be well within what is expected
when using -Ofast but even in that case it would be nice to have it
documented here that that is indeed expected.
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] 6+ messages in thread
* [Bug tree-optimization/113833] 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
@ 2024-02-09 0:55 ` pinskia at gcc dot gnu.org
2024-02-09 1:01 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-09 0:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=60418
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
From https://www.spec.org/cpu2006/Docs/435.gromacs.html :
> The gromacs.out results shouldn't differ by more than 1.25% from the reference values.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/113833] 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
2024-02-09 0:55 ` [Bug tree-optimization/113833] " pinskia at gcc dot gnu.org
@ 2024-02-09 1:01 ` pinskia at gcc dot gnu.org
2024-02-09 6:52 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-02-09 1:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looking at the past issues (which we "fixed"), makes me wonder about the spec
verification testing for gromacs and the use of -Ofast ...
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/113833] 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
2024-02-09 0:55 ` [Bug tree-optimization/113833] " pinskia at gcc dot gnu.org
2024-02-09 1:01 ` pinskia at gcc dot gnu.org
@ 2024-02-09 6:52 ` rguenth at gcc dot gnu.org
2024-02-12 12:57 ` jamborm at gcc dot gnu.org
2024-02-25 11:13 ` pheeck at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2024-02-09 6:52 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
I suspect the issue would pop up with -Ofast -fno-vect-cost-model for any
sub-architecture. The patch referenced just adjusts costs for doing BB
vectorization (and there's reductions there as well). It might be interesting
to offer more high-level knobs to tune for vectorization, say
-fno-vect-bb-reduction or -fforce-in-order-bb-reduction-vectorization.
A compare before/after the patch of -fopt-info-vec output might show the few
cases that are affected by the patch.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/113833] 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
` (2 preceding siblings ...)
2024-02-09 6:52 ` rguenth at gcc dot gnu.org
@ 2024-02-12 12:57 ` jamborm at gcc dot gnu.org
2024-02-25 11:13 ` pheeck at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: jamborm at gcc dot gnu.org @ 2024-02-12 12:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
--- Comment #4 from Martin Jambor <jamborm at gcc dot gnu.org> ---
Created attachment 57397
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57397&action=edit
-fopt-info-vec before/after comparison
(In reply to Richard Biener from comment #3)
> A compare before/after the patch of -fopt-info-vec output might show the few
> cases that are affected by the patch.
I Hope I have not messed anything up. I have added -fopt-info-vec right after
-fprofile-use into the spec config and then grepped the output for
':[^:]*:[^:]*: optimized'. Then I sorted (because the build was parallel) and
compared the output and it seems there are quite a few *fewer* instances of
vectorization happening.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/113833] 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab
2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
` (3 preceding siblings ...)
2024-02-12 12:57 ` jamborm at gcc dot gnu.org
@ 2024-02-25 11:13 ` pheeck at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pheeck at gcc dot gnu.org @ 2024-02-25 11:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113833
Filip Kastl <pheeck at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |pheeck at gcc dot gnu.org
--- Comment #5 from Filip Kastl <pheeck at gcc dot gnu.org> ---
Just posting here to notify that I've found a very similar miscomparison on AMD
Zen CPUs: pr114057
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-02-25 11:13 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2024-02-08 16:37 [Bug tree-optimization/113833] New: 435.gromacs fails verification on with -Ofast -march={cascadelake,icelake-server} and PGO after r14-7272-g57f611604e8bab jamborm at gcc dot gnu.org
2024-02-09 0:55 ` [Bug tree-optimization/113833] " pinskia at gcc dot gnu.org
2024-02-09 1:01 ` pinskia at gcc dot gnu.org
2024-02-09 6:52 ` rguenth at gcc dot gnu.org
2024-02-12 12:57 ` jamborm at gcc dot gnu.org
2024-02-25 11:13 ` pheeck at gcc dot gnu.org
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