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From: "denis.campredon at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/103647] New: constant array comparison not always folded Date: Fri, 10 Dec 2021 11:01:22 +0000 [thread overview] Message-ID: <bug-103647-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103647 Bug ID: 103647 Summary: constant array comparison not always folded Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: denis.campredon at gmail dot com Target Milestone: --- On trunk and gcc 11, with -O2 the following functions are not optimized to xor eax, eax ------------ bool f() { char a[] = {'a', 'c'}; char b[] = {'a', 'b'}; return __builtin_memcmp(a, b, 2); } bool g() { char a[] = {'a', 'b'}; char b[] = {'a', 'b', 'c'}; return __builtin_memcmp(a, b, 2); } ------------ .LC1: .string "ab" .LC0: .string "ac" f(): movzx eax, WORD PTR .LC1[rip] cmp WORD PTR .LC0[rip], ax setne al ret g(): cmp WORD PTR .LC1[rip], 25185 setne al ret
next reply other threads:[~2021-12-10 11:01 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-10 11:01 denis.campredon at gmail dot com [this message] 2021-12-10 20:29 ` [Bug tree-optimization/103647] " pinskia at gcc dot gnu.org 2021-12-10 20:31 ` pinskia at gcc dot gnu.org 2022-01-04 9:24 ` rguenth at gcc dot gnu.org
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