Index: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2827,7 +2827,15 @@
     Known.Zero.setBitsFrom(InVT.getScalarSizeInBits());
     break;
   }
-  // TODO ISD::SIGN_EXTEND_VECTOR_INREG
+  case ISD::SIGN_EXTEND_VECTOR_INREG: {
+    EVT InVT = Op.getOperand(0).getValueType();
+    APInt InDemandedElts = DemandedElts.zextOrSelf(InVT.getVectorNumElements());
+    Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
+    // If the sign bit is known to be zero or one, then sext will extend
+    // it to the top bits, else it will just zext.
+    Known = Known.sext(BitWidth);
+    break;
+  }
   case ISD::SIGN_EXTEND: {
     Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
     // If the sign bit is known to be zero or one, then sext will extend
Index: llvm/trunk/test/CodeGen/X86/combine-shl.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/combine-shl.ll
+++ llvm/trunk/test/CodeGen/X86/combine-shl.ll
@@ -283,17 +283,11 @@
 ; SSE41-LABEL: combine_vec_shl_ext_shl1:
 ; SSE41:       # %bb.0:
 ; SSE41-NEXT:    pmullw {{.*}}(%rip), %xmm0
-; SSE41-NEXT:    pshufd {{.*#+}} xmm1 = xmm0[2,3,0,1]
-; SSE41-NEXT:    pmovsxwd %xmm1, %xmm1
 ; SSE41-NEXT:    pmovsxwd %xmm0, %xmm0
-; SSE41-NEXT:    movdqa %xmm0, %xmm2
-; SSE41-NEXT:    pslld $30, %xmm2
-; SSE41-NEXT:    pslld $31, %xmm0
-; SSE41-NEXT:    pblendw {{.*#+}} xmm0 = xmm0[0,1,2,3],xmm2[4,5,6,7]
-; SSE41-NEXT:    movdqa %xmm1, %xmm2
-; SSE41-NEXT:    pslld $28, %xmm2
-; SSE41-NEXT:    pslld $29, %xmm1
-; SSE41-NEXT:    pblendw {{.*#+}} xmm1 = xmm1[0,1,2,3],xmm2[4,5,6,7]
+; SSE41-NEXT:    pslld $30, %xmm0
+; SSE41-NEXT:    pxor %xmm1, %xmm1
+; SSE41-NEXT:    pblendw {{.*#+}} xmm0 = xmm1[0,1,2,3],xmm0[4,5,6,7]
+; SSE41-NEXT:    pxor %xmm1, %xmm1
 ; SSE41-NEXT:    retq
 ;
 ; AVX-LABEL: combine_vec_shl_ext_shl1: