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From: "drepper.fsp+rhbz at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107043] New: range information not used in popcount Date: Mon, 26 Sep 2022 20:10:20 +0000 [thread overview] Message-ID: <bug-107043-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107043 Bug ID: 107043 Summary: range information not used in popcount Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: drepper.fsp+rhbz at gmail dot com Target Milestone: --- This code could be compiled to a simple return of the value 1 but it isn't because the range information for n does not survive long enough. int g(int n) { n &= 0x8000; if (n == 0) return 1; return __builtin_popcount(n); } The code generated today is lengthy: 0: 81 e7 00 80 00 00 and $0x8000,%edi 6: ba 01 00 00 00 mov $0x1,%edx b: 89 f8 mov %edi,%eax d: c1 e8 0f shr $0xf,%eax 10: 85 ff test %edi,%edi 12: 0f 44 c2 cmove %edx,%eax 15: c3 ret
next reply other threads:[~2022-09-26 20:10 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-26 20:10 drepper.fsp+rhbz at gmail dot com [this message] 2022-09-26 20:27 ` [Bug tree-optimization/107043] " pinskia at gcc dot gnu.org 2022-09-27 10:19 ` drepper.fsp+rhbz at gmail dot com 2022-09-27 14:29 ` aldyh at gcc dot gnu.org 2022-09-27 15:22 ` jakub at gcc dot gnu.org 2023-07-12 21:16 ` cvs-commit at gcc dot gnu.org 2023-07-12 21:19 ` aldyh at gcc dot gnu.org
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