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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/94892] New: (x >> 31) + 1 not getting narrowed to compare Date: Thu, 30 Apr 2020 17:25:03 +0000 [thread overview] Message-ID: <bug-94892-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94892 Bug ID: 94892 Summary: (x >> 31) + 1 not getting narrowed to compare Product: gcc Version: 10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: gabravier at gmail dot com Target Milestone: --- inline int sign(int x) { return (x >> 31) | ((unsigned)-x >> 31); } bool f(int x) { return sign(x) > -1; } With -O3, LLVM produces this : f(int): test edi, edi setns al ret GCC produces this : f(int): sar edi, 31 lea eax, [rdi+1] ret Changing `f` to `(x >> 31) + 1` results in it being optimized optimally
next reply other threads:[~2020-04-30 17:25 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-30 17:25 gabravier at gmail dot com [this message] 2020-04-30 18:34 ` [Bug target/94892] " pinskia at gcc dot gnu.org 2020-04-30 19:32 ` gabravier at gmail dot com 2020-05-01 19:28 ` harald at gigawatt dot nl 2020-08-10 0:19 ` gabravier at gmail dot com 2021-12-15 0:23 ` [Bug tree-optimization/94892] " pinskia at gcc dot gnu.org 2021-12-15 0:31 ` pinskia at gcc dot gnu.org 2023-05-28 23:15 ` pinskia at gcc dot gnu.org
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