[X86] canCreateUndefOrPoisonForTargetNode - X86ISD::VPERMV3 shuffles don't create undef/poison

The operands might contain an undef/poison element, but the shuffle node itself will not create one by itself.

Improves test case from llvm#109272

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -43839,7 +43839,8 @@ bool X86TargetLowering::isGuaranteedNotToBeUndefOrPoisonForTargetNode(
 
   switch (Op.getOpcode()) {
   case X86ISD::PSHUFD:
-  case X86ISD::VPERMILPI: {
+  case X86ISD::VPERMILPI:
+  case X86ISD::VPERMV3: {
     SmallVector<int, 8> Mask;
     SmallVector<SDValue, 2> Ops;
     if (getTargetShuffleMask(Op, true, Ops, Mask)) {
@@ -43883,6 +43884,7 @@ bool X86TargetLowering::canCreateUndefOrPoisonForTargetNode(
     return false;
   case X86ISD::PSHUFD:
   case X86ISD::VPERMILPI:
+  case X86ISD::VPERMV3:
   case X86ISD::UNPCKH:
   case X86ISD::UNPCKL:
     return false;

llvm/test/CodeGen/X86/vector-shuffle-combining-avx512vbmi.ll

@@ -151,10 +151,9 @@ define <64 x i8> @combine_permi2q_pshufb_as_permi2d_mask(<8 x i64> %a0, <8 x i64
 define <64 x i8> @combine_vpermi2var_v64i8_with_mask(<64 x i8> %a0, <64 x i8> %a1, <64 x i8> %a2) {
 ; CHECK-LABEL: combine_vpermi2var_v64i8_with_mask:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    vpermt2b %zmm2, %zmm1, %zmm0
 ; CHECK-NEXT:    vpmovb2m %zmm1, %k0
 ; CHECK-NEXT:    knotq %k0, %k1
-; CHECK-NEXT:    vmovdqu8 %zmm0, %zmm0 {%k1} {z}
+; CHECK-NEXT:    vpermt2b %zmm2, %zmm1, %zmm0 {%k1} {z}
 ; CHECK-NEXT:    ret{{[l|q]}}
   %perm = tail call <64 x i8> @llvm.x86.avx512.vpermi2var.qi.512(<64 x i8> %a0, <64 x i8> %a1, <64 x i8> %a2)
   %cmp = icmp slt <64 x i8> %a1, zeroinitializer