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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/100874] New: [12 Regression] slight missed optimization with min<a,CST>-CST on aarch64 Date: Wed, 02 Jun 2021 09:32:35 +0000 [thread overview] Message-ID: <bug-100874-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100874 Bug ID: 100874 Summary: [12 Regression] slight missed optimization with min<a,CST>-CST on aarch64 Product: gcc Version: 12.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Target: aarch64-*-* Take: int f(int a) { return a < 4 ? a - 4 : 0; } int f1(int a) { int x = a - 4; if (a < 4) return x; return 0; } int f2(int a) { int t = a < 4 ? a : 4; return t - 4; } In GCC 11, we produce: f(int): mov w1, 4 cmp w0, w1 csel w0, w0, w1, le sub w0, w0, #4 ret f1(int): subs w0, w0, 4 csel w0, w0, wzr, lt ret f2(int): mov w1, 4 cmp w0, w1 csel w0, w0, w1, le sub w0, w0, #4 ret On the trunk all three give the same code gen (due to PHI-OPT being improved) but of what f and f2 used to give. All three should produce what f1 had produed instead. This is gcc.target/aarch64/subs_compare_2.c
next reply other threads:[~2021-06-02 9:32 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-02 9:32 pinskia at gcc dot gnu.org [this message] 2021-06-02 9:33 ` [Bug target/100874] " pinskia at gcc dot gnu.org 2021-06-02 9:35 ` pinskia at gcc dot gnu.org 2021-06-02 9:39 ` pinskia at gcc dot gnu.org 2022-02-15 18:10 ` [Bug target/100874] [12 Regression] slight missed optimization with min<a,CST>-CST on aarch64 (subs_compare_2.c) cvs-commit at gcc dot gnu.org 2022-02-15 18:15 ` rsandifo at gcc dot gnu.org
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