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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/96681] New: Failure to optimize xor of comparisons with specific constants to comparison of xor-ed of compared variables Date: Tue, 18 Aug 2020 16:36:53 +0000 [thread overview] Message-ID: <bug-96681-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96681 Bug ID: 96681 Summary: Failure to optimize xor of comparisons with specific constants to comparison of xor-ed of compared variables 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: --- int f(int x, int y) { return (x < 0) ^ (y < 0); } This can be optimized to `return (x ^ y) < 0;`. LLVM does this transformation, but GCC does not. This transformation can also be done with `return (x > -1) ^ (y > -1);`. There is also a similar transformation with `return (x > -1) ^ (y < 0);`, which can be optimized to `return ~(x ^ y) < 0;`.
next reply other threads:[~2020-08-18 16:36 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-18 16:36 gabravier at gmail dot com [this message] 2020-08-25 10:47 ` [Bug tree-optimization/96681] " rguenth at gcc dot gnu.org 2021-01-15 13:22 ` jakub at gcc dot gnu.org 2021-01-15 20:11 ` cvs-commit at gcc dot gnu.org 2021-01-15 20:14 ` jakub at gcc dot gnu.org 2022-11-28 22:42 ` pinskia at gcc dot gnu.org
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