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From: "liuhongt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/114429] New: [x86] (neg a) ashifrt>> 31 can be optimized to a > 0. Date: Fri, 22 Mar 2024 05:39:26 +0000 [thread overview] Message-ID: <bug-114429-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114429 Bug ID: 114429 Summary: [x86] (neg a) ashifrt>> 31 can be optimized to a > 0. Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: liuhongt at gcc dot gnu.org Target Milestone: --- typedef unsigned char uint8_t; uint8_t x264_clip_uint8( int x ) { return x&(~255) ? (-x)>>31 : x; } void foo (int* a, int* __restrict b, int n) { for (int i = 0; i != 8; i++) b[i] = x264_clip_uint8 (a[i]); } gcc -O2 -march=x86-64-v3 -S foo(int*, int*, int): .. mov eax, 255 vpxor xmm0, xmm0, xmm0 vmovd xmm1, eax vpbroadcastd ymm1, xmm1 vmovdqu ymm2, YMMWORD PTR [rdi] vpminud ymm3, ymm2, ymm1 vpsubd ymm0, ymm0, ymm2 vmovdqa YMMWORD PTR [rsp-32], ymm3 vpsrad ymm0, ymm0, 31 vpcmpeqd ymm3, ymm2, YMMWORD PTR [rsp-32] vpblendvb ymm0, ymm0, ymm2, ymm3 vpand ymm1, ymm1, ymm0 vmovdqu YMMWORD PTR [rsi], ymm1 It can be better with mov eax, 255 vmovd xmm1, eax vpxor xmm0, xmm0, xmm0. vpbroadcastd ymm1, xmm1 vmovdqu ymm2, YMMWORD PTR [rdi] vpminud ymm3, ymm2, ymm1 vmovdqa YMMWORD PTR [rsp-32], ymm3 vcmpgtps ymm0, ymm2, ymm0 vpcmpeqd ymm3, ymm2, YMMWORD PTR [rsp-32] vpblendvb ymm0, ymm0, ymm2, ymm3 vpand ymm1, ymm1, ymm0 vmovdqu YMMWORD PTR [rsi], ymm1
next reply other threads:[~2024-03-22 5:39 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-22 5:39 liuhongt at gcc dot gnu.org [this message] 2024-03-22 5:44 ` [Bug target/114429] " liuhongt at gcc dot gnu.org 2024-03-22 6:09 ` liuhongt at gcc dot gnu.org 2024-03-22 6:47 ` liuhongt at gcc dot gnu.org
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