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* [Bug target/95791] New: Unnecessary vzeroupper when only using zmm16 through zmm31
@ 2020-06-20 20:00 josephcsible at gmail dot com
2020-06-20 23:07 ` [Bug target/95791] " hjl.tools at gmail dot com
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: josephcsible at gmail dot com @ 2020-06-20 20:00 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95791
Bug ID: 95791
Summary: Unnecessary vzeroupper when only using zmm16 through
zmm31
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Keywords: missed-optimization, ssemmx
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: josephcsible at gmail dot com
Target Milestone: ---
Target: x86_64-linux-gnu
Consider this C code:
void f(void) {
__asm__ __volatile__("" ::: "zmm16");
}
When compiled with "-O2 -mavx512f", it generates a vzeroupper instruction, but
this is unnecessary, since zmm16 through zmm31 don't cause the performance
penalty, and in fact they aren't even affected by vzeroupper.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/95791] Unnecessary vzeroupper when only using zmm16 through zmm31
2020-06-20 20:00 [Bug target/95791] New: Unnecessary vzeroupper when only using zmm16 through zmm31 josephcsible at gmail dot com
@ 2020-06-20 23:07 ` hjl.tools at gmail dot com
2020-06-22 12:19 ` cvs-commit at gcc dot gnu.org
2020-06-22 13:36 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: hjl.tools at gmail dot com @ 2020-06-20 23:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95791
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2020-06-20
URL| |https://gcc.gnu.org/piperma
| |il/gcc-patches/2020-June/54
| |8648.html
Keywords| |patch
Ever confirmed|0 |1
Target Milestone|--- |11.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/95791] Unnecessary vzeroupper when only using zmm16 through zmm31
2020-06-20 20:00 [Bug target/95791] New: Unnecessary vzeroupper when only using zmm16 through zmm31 josephcsible at gmail dot com
2020-06-20 23:07 ` [Bug target/95791] " hjl.tools at gmail dot com
@ 2020-06-22 12:19 ` cvs-commit at gcc dot gnu.org
2020-06-22 13:36 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-06-22 12:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95791
--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <hjl@gcc.gnu.org>:
https://gcc.gnu.org/g:9302421e71e85b4d3766a534ed9e1c4ae1e7a6ca
commit r11-1585-g9302421e71e85b4d3766a534ed9e1c4ae1e7a6ca
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sat Jun 20 16:02:42 2020 -0700
x86: Skip EXT_REX_SSE_REG_P for vzeroupper optimization
Skip EXT_REX_SSE_REG_P for vzeroupper optimization since upper 16 vector
registers don't trigger SSE <-> AVX transition penalty.
gcc/
PR target/95791
* config/i386/i386.c (ix86_dirflag_mode_needed): Skip
EXT_REX_SSE_REG_P.
gcc/testsuite/
PR target/95791
* gcc.target/i386/pr95791.c: New test.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/95791] Unnecessary vzeroupper when only using zmm16 through zmm31
2020-06-20 20:00 [Bug target/95791] New: Unnecessary vzeroupper when only using zmm16 through zmm31 josephcsible at gmail dot com
2020-06-20 23:07 ` [Bug target/95791] " hjl.tools at gmail dot com
2020-06-22 12:19 ` cvs-commit at gcc dot gnu.org
@ 2020-06-22 13:36 ` hjl.tools at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: hjl.tools at gmail dot com @ 2020-06-22 13:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95791
H.J. Lu <hjl.tools at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed for GCC 11.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-06-22 13:36 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-20 20:00 [Bug target/95791] New: Unnecessary vzeroupper when only using zmm16 through zmm31 josephcsible at gmail dot com
2020-06-20 23:07 ` [Bug target/95791] " hjl.tools at gmail dot com
2020-06-22 12:19 ` cvs-commit at gcc dot gnu.org
2020-06-22 13:36 ` hjl.tools at gmail dot com
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