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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/104610] memcmp () == 0 can be optimized better for avx512f Date: Wed, 28 Jun 2023 11:05:42 +0000 [thread overview] Message-ID: <bug-104610-4-8WHPGMbzZw@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-104610-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104610 --- Comment #21 from Uroš Bizjak <ubizjak at gmail dot com> --- Just before the patch from Comment #20, the compiler creates (-O2 -mavx): --cut here-- vmovdqa .LC1(%rip), %xmm0 vmovdqa %xmm0, -24(%rsp) vmovdqu (%rdi), %xmm0 vpxor .LC0(%rip), %xmm0, %xmm0 vptest %xmm0, %xmm0 je .L5 .L2: movl $1, %eax testl %eax, %eax sete %al ret .L5: vmovdqu 16(%rdi), %xmm0 vpxor -24(%rsp), %xmm0, %xmm0 vptest %xmm0, %xmm0 jne .L2 xorl %eax, %eax testl %eax, %eax sete %al ret --cut here-- Please note the creative way of returning 0 and 1 ... : movl $1, %eax testl %eax, %eax sete %al ret Even the new code (From comment #20) is unnecessarily convoluted: .L2: movl $1, %eax xorl $1, %eax ret .L5: xorl %eax, %eax xorl $1, %eax ret
next prev parent reply other threads:[~2023-06-28 11:05 UTC|newest] Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-21 11:00 [Bug target/104610] New: " pinskia at gcc dot gnu.org 2022-02-21 11:01 ` [Bug target/104610] " pinskia at gcc dot gnu.org 2022-02-22 4:03 ` crazylht at gmail dot com 2022-02-22 5:54 ` crazylht at gmail dot com 2022-02-22 5:55 ` crazylht at gmail dot com 2022-02-22 6:18 ` crazylht at gmail dot com 2022-02-22 6:32 ` crazylht at gmail dot com 2022-02-23 2:15 ` crazylht at gmail dot com 2022-02-23 6:18 ` crazylht at gmail dot com 2022-02-23 21:04 ` hjl.tools at gmail dot com 2022-02-24 5:33 ` crazylht at gmail dot com 2022-02-24 6:00 ` hjl.tools at gmail dot com 2022-02-26 20:26 ` hjl.tools at gmail dot com 2022-02-27 19:02 ` hjl.tools at gmail dot com 2022-02-27 19:29 ` hjl.tools at gmail dot com 2022-03-04 3:03 ` hjl.tools at gmail dot com 2022-03-28 5:05 ` crazylht at gmail dot com 2022-03-28 5:27 ` crazylht at gmail dot com 2022-05-18 2:47 ` cvs-commit at gcc dot gnu.org 2022-05-18 2:49 ` crazylht at gmail dot com 2022-06-16 7:41 ` crazylht at gmail dot com 2023-06-28 10:12 ` cvs-commit at gcc dot gnu.org 2023-06-28 11:05 ` ubizjak at gmail dot com [this message] 2023-10-10 7:37 ` crazylht at gmail dot com 2023-10-30 3:10 ` cvs-commit at gcc dot gnu.org
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