[llvm-bugs] [Bug 30945] New: [AVX512] Failure to flip vector comparison to remove not mask instruction

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=30945

            Bug ID: 30945
           Summary: [AVX512] Failure to flip vector comparison to remove
                    not mask instruction
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: craig.topper at gmail.com, elena.demikhovsky at intel.com,
                    igor.breger at intel.com, llvm-bugs at lists.llvm.org
    Classification: Unclassified

Unearthed by https://reviews.llvm.org/rL286238

define <16 x i32> @test14(<16 x i32>%a, <16 x i32>%b) {
; CHECK-LABEL: test14:
; CHECK:       ## BB#0:
; CHECK-NEXT:    vpsubd %zmm1, %zmm0, %zmm1
; CHECK-NEXT:    vpcmpled %zmm0, %zmm1, %k0
; CHECK-NEXT:    knotw %k0, %k1  <-- REMOVED IF WE USED vpcmpgtd INSTEAD
; CHECK-NEXT:    vmovdqa32 %zmm1, %zmm0 {%k1} {z}
; CHECK-NEXT:    retq
  %sub_r = sub <16 x i32> %a, %b
  %cmp.i2.i = icmp sgt <16 x i32> %sub_r, %a
  %sext.i3.i = sext <16 x i1> %cmp.i2.i to <16 x i32>
  %mask = icmp eq <16 x i32> %sext.i3.i, zeroinitializer
  %res = select <16 x i1> %mask, <16 x i32> zeroinitializer, <16 x i32> %sub_r
  ret <16 x i32>%res
}

define <8 x i64> @test15(<8 x i64>%a, <8 x i64>%b) {
; CHECK-LABEL: test15:
; CHECK:       ## BB#0:
; CHECK-NEXT:    vpsubq %zmm1, %zmm0, %zmm1
; CHECK-NEXT:    vpcmpleq %zmm0, %zmm1, %k0
; CHECK-NEXT:    knotw %k0, %k1m  <-- REMOVED IF WE USED vpcmpgtq INSTEAD
; CHECK-NEXT:    vmovdqa64 %zmm1, %zmm0 {%k1} {z}
; CHECK-NEXT:    retq
  %sub_r = sub <8 x i64> %a, %b
  %cmp.i2.i = icmp sgt <8 x i64> %sub_r, %a
  %sext.i3.i = sext <8 x i1> %cmp.i2.i to <8 x i64>
  %mask = icmp eq <8 x i64> %sext.i3.i, zeroinitializer
  %res = select <8 x i1> %mask, <8 x i64> zeroinitializer, <8 x i64> %sub_r
  ret <8 x i64>%res
}

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