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* [Bug target/94915] New: MAX_EXPR weirdly optimized on x86 with -mtune=core2
@ 2020-05-02 8:20 gabravier at gmail dot com
2020-05-04 6:35 ` [Bug target/94915] " rguenth at gcc dot gnu.org
2021-08-16 21:32 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: gabravier at gmail dot com @ 2020-05-02 8:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94915
Bug ID: 94915
Summary: MAX_EXPR weirdly optimized on x86 with -mtune=core2
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int f(int x, int y)
{
return x > y ? x : y;
}
When compiling with -O3 -mtune=core2 -msse4.1, GCC outputs this :
f(int, int):
movd xmm0, edi
movd xmm1, esi
pmaxsd xmm0, xmm1
movd eax, xmm0
ret
It would seem rather doubtful that this is the optimal solution for doing max
over a simple compare+cmov
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug target/94915] MAX_EXPR weirdly optimized on x86 with -mtune=core2 2020-05-02 8:20 [Bug target/94915] New: MAX_EXPR weirdly optimized on x86 with -mtune=core2 gabravier at gmail dot com @ 2020-05-04 6:35 ` rguenth at gcc dot gnu.org 2021-08-16 21:32 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: rguenth at gcc dot gnu.org @ 2020-05-04 6:35 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94915 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target| |x86_64-*-* --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- We now can move integer operations over to SSE which in some cases (max/min vs. cmov can be quite a bit faster). This isolated case is probably not of such kind (but how can you know w/o benchmarking ...). On AMD archs the GPR <-> xmm moves make this unprofitable but those are "free" on intel which makes costing prefer the pmaxsd variant. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug target/94915] MAX_EXPR weirdly optimized on x86 with -mtune=core2 2020-05-02 8:20 [Bug target/94915] New: MAX_EXPR weirdly optimized on x86 with -mtune=core2 gabravier at gmail dot com 2020-05-04 6:35 ` [Bug target/94915] " rguenth at gcc dot gnu.org @ 2021-08-16 21:32 ` pinskia at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-08-16 21:32 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94915 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2021-08-16 Status|UNCONFIRMED |NEW Ever confirmed|0 |1 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-08-16 21:32 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-05-02 8:20 [Bug target/94915] New: MAX_EXPR weirdly optimized on x86 with -mtune=core2 gabravier at gmail dot com 2020-05-04 6:35 ` [Bug target/94915] " rguenth at gcc dot gnu.org 2021-08-16 21:32 ` pinskia at gcc dot gnu.org
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