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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/102575] New: Failure to optimize double _Complex stores to use largest loads/stores possible Date: Sun, 03 Oct 2021 14:01:34 +0000 [thread overview] Message-ID: <bug-102575-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102575 Bug ID: 102575 Summary: Failure to optimize double _Complex stores to use largest loads/stores possible Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: gabravier at gmail dot com Target Milestone: --- void test(double _Complex *a) { a[0] = 1; a[1] = 1; } With -O3, on AMD64 GCC outputs this: test(double _Complex*): movsd xmm1, QWORD PTR .LC0[rip] movsd xmm0, QWORD PTR .LC0[rip+8] movsd QWORD PTR [rdi], xmm1 movsd QWORD PTR [rdi+8], xmm0 movsd QWORD PTR [rdi+16], xmm1 movsd QWORD PTR [rdi+24], xmm0 ret Clang instead outputs this: test(double _Complex*): movsd xmm0, qword ptr [rip + .LCPI0_0] # xmm0 = mem[0],zero movups xmmword ptr [rdi], xmm0 movups xmmword ptr [rdi + 16], xmm0 ret It seems to me like the second output should always be faster. PS: The difference is even larger with `-mavx2`.
next reply other threads:[~2021-10-03 14:01 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-03 14:01 gabravier at gmail dot com [this message] 2021-10-03 18:48 ` [Bug tree-optimization/102575] " pinskia at gcc dot gnu.org 2021-10-04 7:21 ` rguenth at gcc dot gnu.org 2022-07-20 8:18 ` crazylht at gmail dot com 2022-07-20 9:06 ` rguenth at gcc dot gnu.org
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