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From: "goon.pri.low at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/112687] New: missed-optimization: switch statement does not simplify to it's expression Date: Thu, 23 Nov 2023 21:43:03 +0000 [thread overview] Message-ID: <bug-112687-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112687 Bug ID: 112687 Summary: missed-optimization: switch statement does not simplify to it's expression Product: gcc Version: 13.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: goon.pri.low at gmail dot com Target Milestone: --- This following code: int unopt(int v) { switch (v & 3) { case 0: return 0; case 1: return 1; case 2: return 2; case 3: return 3; default: __builtin_unreachable(); } } unopt: mov eax, edi and eax, 3 lea edx, [rax-1] cmp edx, 3 mov edx, 0 cmovnb eax, edx ret Ought to be optimized to: int opt(int v) { return v & 3; } opt: mov eax, edi and eax, 3 ret Note: I decided to separate this problem from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112645 since it was unrelated to the main bug, though Richard offers some initial insight into the problem.
next reply other threads:[~2023-11-23 21:43 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-23 21:43 goon.pri.low at gmail dot com [this message] 2023-11-24 8:04 ` [Bug tree-optimization/112687] " rguenth at gcc dot gnu.org 2024-01-26 11:59 ` fkastl at suse dot cz
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