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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] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 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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