[llvm-bugs] [Bug 50603] New: Suboptimal codegen for vector pattern M < 0 ? X : Y

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50603

            Bug ID: 50603
           Summary: Suboptimal codegen for vector pattern M < 0 ? X : Y
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, pengfei.wang at intel.com,
                    spatel+llvm at rotateright.com

typedef int V __attribute__((vector_size(16)));

V lt_zero_x_y(V mask, V x, V y) { return mask <  0 ? x : y; }

GCC 9+ -O3 -mavx512f 
lt_zero_x_y(int __vector(4), int __vector(4), int __vector(4)):
  vblendvps xmm0, xmm2, xmm1, xmm0
  ret

LLVM  -O3 -mavx512f 
lt_zero_x_y(int __vector(4), int __vector(4), int __vector(4)):               #
@lt_zero_x_y(int __vector(4), int __vector(4), int __vector(4))
        vpcmpeqd        xmm3, xmm3, xmm3
        vpcmpgtd        k1, zmm0, zmm3
        vpblendmd       zmm0 {k1}, zmm1, zmm2
        vzeroupper
        ret


https://godbolt.org/z/W9fshMoao

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