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* [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern @ 2021-02-01 8:47 gabravier at gmail dot com 2021-02-01 8:54 ` [Bug tree-optimization/98909] " gabravier at gmail dot com ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: gabravier at gmail dot com @ 2021-02-01 8:47 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909 Bug ID: 98909 Summary: Failure to optimize odd loop pattern 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 x) { bool odd = false; while (x > 0) { x--; odd = !odd; } return odd; } This can be optimized to `return (x > 0) && ((x & 1) != 0);`. This transformation is done by LLVM, but not by GCC. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/98909] Failure to optimize odd loop pattern 2021-02-01 8:47 [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern gabravier at gmail dot com @ 2021-02-01 8:54 ` gabravier at gmail dot com 2021-02-02 8:10 ` rguenth at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: gabravier at gmail dot com @ 2021-02-01 8:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909 --- Comment #1 from Gabriel Ravier <gabravier at gmail dot com> --- PS: The same pattern with `unsigned` replacing `int` can be optimized to `return x & 1;` (done by LLVM, but not by GCC). ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/98909] Failure to optimize odd loop pattern 2021-02-01 8:47 [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern gabravier at gmail dot com 2021-02-01 8:54 ` [Bug tree-optimization/98909] " gabravier at gmail dot com @ 2021-02-02 8:10 ` rguenth at gcc dot gnu.org 2021-07-28 21:24 ` pinskia at gcc dot gnu.org 2024-06-06 0:58 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-02-02 8:10 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2021-02-02 Status|UNCONFIRMED |NEW Ever confirmed|0 |1 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. Final value replacement just uses SCEV. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/98909] Failure to optimize odd loop pattern 2021-02-01 8:47 [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern gabravier at gmail dot com 2021-02-01 8:54 ` [Bug tree-optimization/98909] " gabravier at gmail dot com 2021-02-02 8:10 ` rguenth at gcc dot gnu.org @ 2021-07-28 21:24 ` pinskia at gcc dot gnu.org 2024-06-06 0:58 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2021-07-28 21:24 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/98909] Failure to optimize odd loop pattern 2021-02-01 8:47 [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern gabravier at gmail dot com ` (2 preceding siblings ...) 2021-07-28 21:24 ` pinskia at gcc dot gnu.org @ 2024-06-06 0:58 ` pinskia at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-06-06 0:58 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909 --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Note this is very similar to PR 112104, in that `~a` can be treated as `a ^ -1`. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-06-06 0:58 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-02-01 8:47 [Bug tree-optimization/98909] New: Failure to optimize odd loop pattern gabravier at gmail dot com 2021-02-01 8:54 ` [Bug tree-optimization/98909] " gabravier at gmail dot com 2021-02-02 8:10 ` rguenth at gcc dot gnu.org 2021-07-28 21:24 ` pinskia at gcc dot gnu.org 2024-06-06 0:58 ` pinskia at gcc dot gnu.org
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