1 files changed, 43 insertions, 19 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 5d81debb5f6..838e75b4b36 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -20144,33 +20144,43 @@ static SDValue LowerMUL(SDValue Op, const X86Subtarget &Subtarget,
   //  AloBhi = psllqi(AloBhi, 32);
   //  AhiBlo = psllqi(AhiBlo, 32);
   //  return AloBlo + AloBhi + AhiBlo;
+  APInt LowerBitsMask = APInt::getLowBitsSet(64, 32);
+  bool ALoiIsZero = DAG.MaskedValueIsZero(A, LowerBitsMask);
+  bool BLoiIsZero = DAG.MaskedValueIsZero(B, LowerBitsMask);
 
-  SDValue Ahi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, A, 32, DAG);
-  SDValue Bhi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, B, 32, DAG);
+  APInt UpperBitsMask = APInt::getHighBitsSet(64, 32);
+  bool AHiIsZero = DAG.MaskedValueIsZero(A, UpperBitsMask);
+  bool BHiIsZero = DAG.MaskedValueIsZero(B, UpperBitsMask);
 
-  SDValue AhiBlo = Ahi;
-  SDValue AloBhi = Bhi;
   // Bit cast to 32-bit vectors for MULUDQ
   MVT MulVT = (VT == MVT::v2i64) ? MVT::v4i32 :
                                   (VT == MVT::v4i64) ? MVT::v8i32 : MVT::v16i32;
-  A = DAG.getBitcast(MulVT, A);
-  B = DAG.getBitcast(MulVT, B);
-  Ahi = DAG.getBitcast(MulVT, Ahi);
-  Bhi = DAG.getBitcast(MulVT, Bhi);
-
-  SDValue AloBlo = DAG.getNode(X86ISD::PMULUDQ, dl, VT, A, B);
-  // After shifting right const values the result may be all-zero.
-  if (!ISD::isBuildVectorAllZeros(Ahi.getNode())) {
-    AhiBlo = DAG.getNode(X86ISD::PMULUDQ, dl, VT, Ahi, B);
-    AhiBlo = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, AhiBlo, 32, DAG);
-  }
-  if (!ISD::isBuildVectorAllZeros(Bhi.getNode())) {
-    AloBhi = DAG.getNode(X86ISD::PMULUDQ, dl, VT, A, Bhi);
+  SDValue Alo = DAG.getBitcast(MulVT, A);
+  SDValue Blo = DAG.getBitcast(MulVT, B);
+
+  SDValue Res;
+
+  // Only multiply lo/hi halves that aren't known to be zero.
+  if (!ALoiIsZero && !BLoiIsZero)
+    Res = DAG.getNode(X86ISD::PMULUDQ, dl, VT, Alo, Blo);
+
+  if (!ALoiIsZero && !BHiIsZero) {
+    SDValue Bhi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, B, 32, DAG);
+    Bhi = DAG.getBitcast(MulVT, Bhi);
+    SDValue AloBhi = DAG.getNode(X86ISD::PMULUDQ, dl, VT, Alo, Bhi);
     AloBhi = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, AloBhi, 32, DAG);
+    Res = (Res.getNode() ? DAG.getNode(ISD::ADD, dl, VT, Res, AloBhi) : AloBhi);
   }
 
-  SDValue Res = DAG.getNode(ISD::ADD, dl, VT, AloBlo, AloBhi);
-  return DAG.getNode(ISD::ADD, dl, VT, Res, AhiBlo);
+  if (!AHiIsZero && !BLoiIsZero) {
+    SDValue Ahi = getTargetVShiftByConstNode(X86ISD::VSRLI, dl, VT, A, 32, DAG);
+    Ahi = DAG.getBitcast(MulVT, Ahi);
+    SDValue AhiBlo = DAG.getNode(X86ISD::PMULUDQ, dl, VT, Ahi, Blo);
+    AhiBlo = getTargetVShiftByConstNode(X86ISD::VSHLI, dl, VT, AhiBlo, 32, DAG);
+    Res = (Res.getNode() ? DAG.getNode(ISD::ADD, dl, VT, Res, AhiBlo) : AhiBlo);
+  }
+
+  return (Res.getNode() ? Res : getZeroVector(VT, Subtarget, DAG, dl));
 }
 
 static SDValue LowerMULH(SDValue Op, const X86Subtarget &Subtarget,
@@ -25256,6 +25266,20 @@ void X86TargetLowering::computeKnownBitsForTargetNode(const SDValue Op,
     KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - NumLoBits);
     break;
   }
+  case X86ISD::VZEXT: {
+    SDValue N0 = Op.getOperand(0);
+    unsigned NumElts = Op.getValueType().getVectorNumElements();
+    unsigned InNumElts = N0.getValueType().getVectorNumElements();
+    unsigned InBitWidth = N0.getValueType().getScalarSizeInBits();
+
+    KnownZero = KnownOne = APInt(InBitWidth, 0);
+    APInt DemandedElts = APInt::getLowBitsSet(InNumElts, NumElts);
+    DAG.computeKnownBits(N0, KnownZero, KnownOne, DemandedElts, Depth + 1);
+    KnownOne = KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - InBitWidth);
+    break;
+  }
   }
 }