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* [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self
@ 2020-08-25 12:12 gabravier at gmail dot com
2020-08-25 12:17 ` [Bug tree-optimization/96782] " rguenth at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: gabravier at gmail dot com @ 2020-08-25 12:12 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96782
Bug ID: 96782
Summary: Failure to optimize comparison with bitwise not-ed
with self
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
bool f(int a)
{
return a == ~a;
}
This can be optimized to `return false;`. This transformation is done by LLVM,
but not by GCC.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/96782] Failure to optimize comparison with bitwise not-ed with self
2020-08-25 12:12 [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self gabravier at gmail dot com
@ 2020-08-25 12:17 ` rguenth at gcc dot gnu.org
2021-01-02 9:42 ` jakub at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2020-08-25 12:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96782
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2020-08-25
Status|UNCONFIRMED |NEW
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/96782] Failure to optimize comparison with bitwise not-ed with self
2020-08-25 12:12 [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self gabravier at gmail dot com
2020-08-25 12:17 ` [Bug tree-optimization/96782] " rguenth at gcc dot gnu.org
@ 2021-01-02 9:42 ` jakub at gcc dot gnu.org
2021-01-04 9:37 ` cvs-commit at gcc dot gnu.org
2021-01-04 9:38 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-01-02 9:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96782
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|prathamesh3492 at gcc dot gnu.org |jakub at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 49867
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49867&action=edit
gcc11-pr96782.patch
Untested fix.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/96782] Failure to optimize comparison with bitwise not-ed with self
2020-08-25 12:12 [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self gabravier at gmail dot com
2020-08-25 12:17 ` [Bug tree-optimization/96782] " rguenth at gcc dot gnu.org
2021-01-02 9:42 ` jakub at gcc dot gnu.org
@ 2021-01-04 9:37 ` cvs-commit at gcc dot gnu.org
2021-01-04 9:38 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-01-04 9:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96782
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:
https://gcc.gnu.org/g:ad64e807ffca93e927b68f1aa0cea54dacbe9afd
commit r11-6433-gad64e807ffca93e927b68f1aa0cea54dacbe9afd
Author: Jakub Jelinek <jakub@redhat.com>
Date: Mon Jan 4 10:37:12 2021 +0100
match.pd: Fold x == ~x to false [PR96782]
x is never equal to ~x, so we can fold such comparisons to constants.
2021-01-04 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/96782
* match.pd (x == ~x -> false, x != ~x -> true): New
simplifications.
* gcc.dg/tree-ssa/pr96782.c: New test.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/96782] Failure to optimize comparison with bitwise not-ed with self
2020-08-25 12:12 [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self gabravier at gmail dot com
` (2 preceding siblings ...)
2021-01-04 9:37 ` cvs-commit at gcc dot gnu.org
@ 2021-01-04 9:38 ` jakub at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-01-04 9:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96782
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for GCC 11.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-01-04 9:38 UTC | newest]
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2020-08-25 12:12 [Bug tree-optimization/96782] New: Failure to optimize comparison with bitwise not-ed with self gabravier at gmail dot com
2020-08-25 12:17 ` [Bug tree-optimization/96782] " rguenth at gcc dot gnu.org
2021-01-02 9:42 ` jakub at gcc dot gnu.org
2021-01-04 9:37 ` cvs-commit at gcc dot gnu.org
2021-01-04 9:38 ` jakub at gcc dot gnu.org
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