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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/109657] New: (a ? -1 : 0) | b could be optimized better for aarch64 Date: Thu, 27 Apr 2023 22:47:15 +0000 [thread overview] Message-ID: <bug-109657-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109657 Bug ID: 109657 Summary: (a ? -1 : 0) | b could be optimized better for aarch64 Product: gcc Version: 13.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: target Assignee: pinskia at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Target: aarch64-*-* Take (at -O2): ``` unsigned b(unsigned a, unsigned b){ if(b){ return -1; } return a; } unsigned b1(unsigned a, unsigned b){ unsigned t = b ? -1 : 0; return a | t; } ``` Right now we produce: ``` b: cmp w1, 0 csinv w0, w0, wzr, eq ret b1: cmp w1, 0 csetm w1, ne orr w0, w1, w0 ret ``` We can help combine here by adding a pattern for: (set (reg/i:SI 0 x0) (ior:SI (neg:SI (ne:SI (reg:CC 66 cc) (const_int 0 [0]))) (reg:SI 102))) Which is the same as (set (reg/i:SI 0 x0) (if_then_else:SI (eq (reg:CC 66 cc) (const_int 0 [0])) (reg:SI 97) (const_int -1 [0xffffffffffffffff]))) pattern. I suspect both are considered canonical too.
next reply other threads:[~2023-04-27 22:47 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-04-27 22:47 pinskia at gcc dot gnu.org [this message] 2023-04-28 5:07 ` [Bug target/109657] " pinskia at gcc dot gnu.org 2023-04-28 23:35 ` pinskia at gcc dot gnu.org 2023-05-02 21:10 ` cvs-commit at gcc dot gnu.org 2023-05-02 21:11 ` pinskia at gcc dot gnu.org
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