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From: "rsandifo at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/114603] New: aarch64: Invalid SVE cnot optimisation Date: Fri, 05 Apr 2024 12:29:09 +0000 [thread overview] Message-ID: <bug-114603-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114603 Bug ID: 114603 Summary: aarch64: Invalid SVE cnot optimisation Product: gcc Version: 14.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: rsandifo at gcc dot gnu.org Target Milestone: --- Target: aarch64*-*-* An overly lax condition on the cnot combine pattern means that we optimise: #include <arm_sve.h> svint32_t foo(svbool_t pg, svint32_t y) { return svsel(svcmpeq(pg, y, 0), svdup_s32(1), svdup_s32(0)); } to a single cnot: foo: cnot z0.s, p0/m, z0.s ret The result must be 0 for inactive elements of pg, whereas the above would leave the elements unchanged instead. This seems to have been around since the SVE ACLE was first added.
next reply other threads:[~2024-04-05 12:29 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-04-05 12:29 rsandifo at gcc dot gnu.org [this message] 2024-04-05 13:47 ` [Bug target/114603] " cvs-commit at gcc dot gnu.org 2024-04-05 15:45 ` rsandifo at gcc dot gnu.org
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