[DAGCombiner] Remove shuffle support from simplifyShuffleMask

rL310372 enabled simplifyShuffleMask to support undef shuffle mask inputs, but its causing hangs. Removing support until I can triage the problem git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310699 91177308-0d34-0410-b5e6-96231b3b80d8

Author: RKSimon

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -15161,8 +15161,6 @@ static SDValue simplifyShuffleMask(ShuffleVectorSDNode *SVN, SDValue N0,
  // TODO - handle more cases as required.
  if (V.getOpcode() == ISD::BUILD_VECTOR)
  return V.getOperand(Idx).isUndef();
- if (auto *SVN = dyn_cast<ShuffleVectorSDNode>(V))
- return SVN->getMaskElt(Idx) < 0;
  return false;
  };
 

test/CodeGen/X86/oddshuffles.ll

@@ -258,7 +258,7 @@ define void @v7i8(<4 x i8> %a, <4 x i8> %b, <7 x i8>* %p) nounwind {
 ; SSE42-NEXT: pextrb $0, %xmm1, 6(%rdi)
 ; SSE42-NEXT: pshufb {{.*#+}} xmm1 = xmm1[8,9,8,9,4,5,8,9,0,1,12,13,0,1,14,15]
 ; SSE42-NEXT: pblendw {{.*#+}} xmm1 = xmm0[0],xmm1[1],xmm0[2],xmm1[3],xmm0[4],xmm1[5,6,7]
-; SSE42-NEXT: pshufb {{.*#+}} xmm1 = xmm1[0,2,4,6,8,10,12,u,u,u,u,u,u,u,u,u]
+; SSE42-NEXT: pshufb {{.*#+}} xmm1 = xmm1[0,2,4,6,8,10,12,14,u,u,u,u,u,u,u,u]
 ; SSE42-NEXT: pextrw $2, %xmm1, 4(%rdi)
 ; SSE42-NEXT: movd %xmm1, (%rdi)
 ; SSE42-NEXT: retq
@@ -268,7 +268,7 @@ define void @v7i8(<4 x i8> %a, <4 x i8> %b, <7 x i8>* %p) nounwind {
 ; AVX-NEXT: vpshufd {{.*#+}} xmm0 = xmm0[0,3,1,3]
 ; AVX-NEXT: vpshufb {{.*#+}} xmm2 = xmm1[8,9,8,9,4,5,8,9,0,1,12,13,0,1,14,15]
 ; AVX-NEXT: vpblendw {{.*#+}} xmm0 = xmm0[0],xmm2[1],xmm0[2],xmm2[3],xmm0[4],xmm2[5,6,7]
-; AVX-NEXT: vpshufb {{.*#+}} xmm0 = xmm0[0,2,4,6,8,10,12,u,u,u,u,u,u,u,u,u]
+; AVX-NEXT: vpshufb {{.*#+}} xmm0 = xmm0[0,2,4,6,8,10,12,14,u,u,u,u,u,u,u,u]
 ; AVX-NEXT: vpextrb $0, %xmm1, 6(%rdi)
 ; AVX-NEXT: vpextrw $2, %xmm0, 4(%rdi)
 ; AVX-NEXT: vmovd %xmm0, (%rdi)