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From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/104401] New: [x86] Failure to recognize min/max pattern
 using pcmp+pblendv
Date: Sat, 05 Feb 2022 21:32:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104401

            Bug ID: 104401
           Summary: [x86] Failure to recognize min/max pattern using
                    pcmp+pblendv
           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: ---

#include <smmintrin.h>

__m128i min32(__m128i value, __m128i input)
{
  return _mm_blendv_epi8(input, value, _mm_cmplt_epi32(value, input));
}

With -O3 -msse4.1, GCC outputs this:

min32(long long __vector(2), long long __vector(2)):
  movdqa xmm2, xmm0
  movdqa xmm0, xmm1
  movdqa xmm3, xmm1
  pcmpgtd xmm0, xmm2
  pblendvb xmm3, xmm2, xmm0
  movdqa xmm0, xmm3
  ret

LLVM instead outputs this:

min32(long long __vector(2), long long __vector(2)):
  pminsd xmm0, xmm1
  ret

The equivalent code with cmpgt used instead of cmplt can be optimized to
pmaxsd.=