[llvm] r356327 - [DAGCombine] combineShuffleOfScalars - handle non-zero SCALAR_TO_VECTOR indices (PR41097)

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Sat Mar 16 10:36:26 2019
New Revision: 356327

URL: http://llvm.org/viewvc/llvm-project?rev=356327&view=rev
Log:
[DAGCombine] combineShuffleOfScalars - handle non-zero SCALAR_TO_VECTOR indices (PR41097)

rL356292 reduces the size of scalar_to_vector if we know the upper bits are undef - which means that shuffles may find they are suddenly referencing scalar_to_vector elements other than zero - so make sure we handle this as undef.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/X86/oddshuffles.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=356327&r1=356326&r2=356327&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sat Mar 16 10:36:26 2019
@@ -17596,8 +17596,8 @@ static SDValue combineShuffleOfScalars(S
       if (S.getOpcode() == ISD::BUILD_VECTOR) {
         Op = S.getOperand(Idx);
       } else if (S.getOpcode() == ISD::SCALAR_TO_VECTOR) {
-        assert(Idx == 0 && "Unexpected SCALAR_TO_VECTOR operand index.");
-        Op = S.getOperand(0);
+        SDValue Op0 = S.getOperand(0);
+        Op = Idx == 0 ? Op0 : DAG.getUNDEF(Op0.getValueType());
       } else {
         // Operand can't be combined - bail out.
         return SDValue();

Modified: llvm/trunk/test/CodeGen/X86/oddshuffles.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/oddshuffles.ll?rev=356327&r1=356326&r2=356327&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/oddshuffles.ll (original)
+++ llvm/trunk/test/CodeGen/X86/oddshuffles.ll Sat Mar 16 10:36:26 2019
@@ -1767,3 +1767,57 @@ define <2 x double> @wrongorder(<4 x dou
   %m4 = shufflevector <8 x double> %m3, <8 x double> undef, <2 x i32> <i32 2, i32 0>
   ret <2 x double> %m4
 }
+
+define void @PR41097() {
+; SSE2-LABEL: PR41097:
+; SSE2:       # %bb.0:
+; SSE2-NEXT:    movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; SSE2-NEXT:    movzwl (%rax), %eax
+; SSE2-NEXT:    movd %eax, %xmm1
+; SSE2-NEXT:    shufps {{.*#+}} xmm1 = xmm1[0,0],xmm0[2,0]
+; SSE2-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,1,1,3,4,5,6,7]
+; SSE2-NEXT:    shufps {{.*#+}} xmm0 = xmm0[0,1],xmm1[0,2]
+; SSE2-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,2,2,3,4,5,6,7]
+; SSE2-NEXT:    pshufhw {{.*#+}} xmm0 = xmm0[0,1,2,3,4,6,6,7]
+; SSE2-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
+; SSE2-NEXT:    punpcklbw {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
+; SSE2-NEXT:    pshuflw {{.*#+}} xmm0 = xmm0[0,0,2,3,4,5,6,7]
+; SSE2-NEXT:    psrad $24, %xmm0
+; SSE2-NEXT:    xorps %xmm1, %xmm1
+; SSE2-NEXT:    punpckldq {{.*#+}} xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]
+; SSE2-NEXT:    movdqu %xmm0, (%rax)
+; SSE2-NEXT:    retq
+;
+; SSE42-LABEL: PR41097:
+; SSE42:       # %bb.0:
+; SSE42-NEXT:    movd {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; SSE42-NEXT:    pshufb {{.*#+}} xmm0 = xmm0[0,3,u,u,u,u,u,u,u,u,u,u,u,u,u,u]
+; SSE42-NEXT:    pmovsxbd %xmm0, %xmm0
+; SSE42-NEXT:    pmovzxdq {{.*#+}} xmm0 = xmm0[0],zero,xmm0[1],zero
+; SSE42-NEXT:    movdqu %xmm0, (%rax)
+; SSE42-NEXT:    retq
+;
+; AVX-LABEL: PR41097:
+; AVX:       # %bb.0:
+; AVX-NEXT:    vmovd {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; AVX-NEXT:    vpshufb {{.*#+}} xmm0 = xmm0[0,3,u,u,u,u,u,u,u,u,u,u,u,u,u,u]
+; AVX-NEXT:    vpmovsxbd %xmm0, %xmm0
+; AVX-NEXT:    vpmovzxdq {{.*#+}} xmm0 = xmm0[0],zero,xmm0[1],zero
+; AVX-NEXT:    vmovdqu %xmm0, (%rax)
+; AVX-NEXT:    retq
+;
+; XOP-LABEL: PR41097:
+; XOP:       # %bb.0:
+; XOP-NEXT:    vmovd {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; XOP-NEXT:    vpshufb {{.*#+}} xmm0 = xmm0[0,3,u,u,u,u,u,u,u,u,u,u,u,u,u,u]
+; XOP-NEXT:    vpmovsxbd %xmm0, %xmm0
+; XOP-NEXT:    vpmovzxdq {{.*#+}} xmm0 = xmm0[0],zero,xmm0[1],zero
+; XOP-NEXT:    vmovdqu %xmm0, (%rax)
+; XOP-NEXT:    retq
+  %wide.vec = load <6 x i8>, <6 x i8>* undef, align 1
+  %strided.vec = shufflevector <6 x i8> %wide.vec, <6 x i8> undef, <2 x i32> <i32 0, i32 3>
+  %tmp = sext <2 x i8> %strided.vec to <2 x i32>
+  %tmp7 = zext <2 x i32> %tmp to <2 x i64>
+  store <2 x i64> %tmp7, <2 x i64>* undef, align 8
+  ret void
+}