1 files changed, 31 insertions, 9 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 63874767b71..5303d7a406a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -5848,17 +5848,39 @@ static bool getFauxShuffleMask(SDValue N, SmallVectorImpl<int> &Mask,
     return true;
   }
   case ISD::SCALAR_TO_VECTOR: {
-    // Match against a scalar_to_vector of an extract from a similar vector.
+    // Match against a scalar_to_vector of an extract from a vector,
+    // for PEXTRW/PEXTRB we must handle the implicit zext of the scalar.
     SDValue N0 = N.getOperand(0);
-    if (N0.getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
-        N0.getOperand(0).getValueType() != VT ||
-        !isa<ConstantSDNode>(N0.getOperand(1)) ||
-        NumElts <= N0.getConstantOperandVal(1) ||
-        !N->isOnlyUserOf(N0.getNode()))
+    SDValue SrcExtract;
+
+    if (N0.getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
+        N0.getOperand(0).getValueType() == VT) {
+      SrcExtract = N0;
+    } else if (N0.getOpcode() == ISD::AssertZext &&
+               N0.getOperand(0).getOpcode() == X86ISD::PEXTRW &&
+               cast<VTSDNode>(N0.getOperand(1))->getVT() == MVT::i16) {
+      SrcExtract = N0.getOperand(0);
+      assert(SrcExtract.getOperand(0).getValueType() == MVT::v8i16);
+    } else if (N0.getOpcode() == ISD::AssertZext &&
+               N0.getOperand(0).getOpcode() == X86ISD::PEXTRB &&
+               cast<VTSDNode>(N0.getOperand(1))->getVT() == MVT::i8) {
+      SrcExtract = N0.getOperand(0);
+      assert(SrcExtract.getOperand(0).getValueType() == MVT::v16i8);
+    }
+
+    if (!SrcExtract || !isa<ConstantSDNode>(SrcExtract.getOperand(1)) ||
+        NumElts <= SrcExtract.getConstantOperandVal(1))
       return false;
-    Ops.push_back(N0.getOperand(0));
-    Mask.push_back(N0.getConstantOperandVal(1));
-    Mask.append(NumElts - 1, SM_SentinelUndef);
+
+    SDValue SrcVec = SrcExtract.getOperand(0);
+    EVT SrcVT = SrcVec.getValueType();
+    unsigned NumSrcElts = SrcVT.getVectorNumElements();
+    unsigned NumZeros = (NumBitsPerElt / SrcVT.getScalarSizeInBits()) - 1;
+
+    Ops.push_back(SrcVec);
+    Mask.push_back(SrcExtract.getConstantOperandVal(1));
+    Mask.append(NumZeros, SM_SentinelZero);
+    Mask.append(NumSrcElts - Mask.size(), SM_SentinelUndef);
     return true;
   }
   case X86ISD::PINSRB: