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* [Bug rtl-optimization/94796] New: Failure to reuse flags from substraction
@ 2020-04-27 12:32 gabravier at gmail dot com
2020-04-27 13:06 ` [Bug rtl-optimization/94796] " rguenth at gcc dot gnu.org
2020-04-27 19:58 ` pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: gabravier at gmail dot com @ 2020-04-27 12:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94796
Bug ID: 94796
Summary: Failure to reuse flags from substraction
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
int f(int a, int b)
{
return ((a == b) & (a - b));
}
The `a == b` is able to use condition flags resulting from `a - b`, and thus
avoid an extra compare. LLVM does this transformation, but GCC does not.
https://godbolt.org/z/SHvTW8
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug rtl-optimization/94796] Failure to reuse flags from substraction
2020-04-27 12:32 [Bug rtl-optimization/94796] New: Failure to reuse flags from substraction gabravier at gmail dot com
@ 2020-04-27 13:06 ` rguenth at gcc dot gnu.org
2020-04-27 19:58 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-04-27 13:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94796
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Keywords| |missed-optimization
Last reconfirmed| |2020-04-27
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug rtl-optimization/94796] Failure to reuse flags from substraction
2020-04-27 12:32 [Bug rtl-optimization/94796] New: Failure to reuse flags from substraction gabravier at gmail dot com
2020-04-27 13:06 ` [Bug rtl-optimization/94796] " rguenth at gcc dot gnu.org
@ 2020-04-27 19:58 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2020-04-27 19:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94796
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think this is a dup of bug 3507.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-04-27 19:58 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-04-27 12:32 [Bug rtl-optimization/94796] New: Failure to reuse flags from substraction gabravier at gmail dot com
2020-04-27 13:06 ` [Bug rtl-optimization/94796] " rguenth at gcc dot gnu.org
2020-04-27 19:58 ` pinskia at gcc dot gnu.org
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