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From: "ktkachov at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/98477] New: aarch64: Unnecessary GPR -> FPR moves for conditional select Date: Wed, 30 Dec 2020 09:35:35 +0000 [thread overview] Message-ID: <bug-98477-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98477 Bug ID: 98477 Summary: aarch64: Unnecessary GPR -> FPR moves for conditional select Product: gcc Version: unknown Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: ktkachov at gcc dot gnu.org Target Milestone: --- Target: aarch64 Code like void foo (int a, double *b) { *b = a ? 10000.0 : 200.0; } generates: foo: cmp w0, 0 mov x2, 149533581377536 movk x2, 0x40c3, lsl 48 mov x0, 4641240890982006784 fmov d0, x2 fmov d1, x0 fcsel d0, d0, d1, ne str d0, [x1] ret We don't need to do the FCSEL on the FPR side if we're just storing it to memory. We can just do a GPR CSEL and avoid the FMOVs. I've seen this pattern in the disassembly of some math library routines. Maybe we should add a =w,w,w alternative to the CSEL patterns in the backend?
next reply other threads:[~2020-12-30 9:35 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-30 9:35 ktkachov at gcc dot gnu.org [this message] 2020-12-30 9:40 ` [Bug target/98477] " ktkachov at gcc dot gnu.org 2020-12-30 9:47 ` pinskia at gcc dot gnu.org 2020-12-30 9:50 ` pinskia at gcc dot gnu.org 2020-12-30 9:50 ` pinskia at gcc dot gnu.org 2023-11-18 6:59 ` pinskia at gcc dot gnu.org 2024-04-24 0:02 ` pinskia at gcc dot gnu.org 2024-04-24 6:05 ` pinskia at gcc dot gnu.org 2024-04-24 6:09 ` pinskia at gcc dot gnu.org 2024-04-24 6:22 ` pinskia at gcc dot gnu.org 2024-04-24 6:28 ` pinskia at gcc dot gnu.org 2024-05-06 18:29 ` pinskia at gcc dot gnu.org
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