1 files changed, 44 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1a9cac23399..182e9116bfb 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -10747,6 +10747,42 @@ static SDValue lower256BitVectorShuffle(SDValue Op, SDValue V1, SDValue V2,
   }
 }
 
+/// \brief Try to lower a vector shuffle as a 128-bit shuffles.
+static SDValue lowerV4X128VectorShuffle(SDLoc DL, MVT VT,
+                                             ArrayRef<int> Mask,
+                                             SDValue V1, SDValue V2,
+                                             SelectionDAG &DAG) {
+  assert(VT.getScalarSizeInBits() == 64 &&
+         "Unexpected element type size for 128bit shuffle.");
+
+  // To handle 256 bit vector requires VLX and most probably
+  // function lowerV2X128VectorShuffle() is better solution.
+  assert(VT.getSizeInBits() == 512 &&
+         "Unexpected vector size for 128bit shuffle.");
+
+  SmallVector<int, 4> WidenedMask;
+  if (!canWidenShuffleElements(Mask, WidenedMask))
+    return SDValue();
+
+  // Form a 128-bit permutation.
+  // Convert the 64-bit shuffle mask selection values into 128-bit selection
+  // bits defined by a vshuf64x2 instruction's immediate control byte.
+  unsigned PermMask = 0, Imm = 0;
+  unsigned ControlBitsNum = WidenedMask.size() / 2;
+
+  for (int i = 0, Size = WidenedMask.size(); i < Size; ++i) {
+    if (WidenedMask[i] == SM_SentinelZero)
+      return SDValue();
+
+    // Use first element in place of undef mask.
+    Imm = (WidenedMask[i] == SM_SentinelUndef) ? 0 : WidenedMask[i];
+    PermMask |= (Imm % WidenedMask.size()) << (i * ControlBitsNum);
+  }
+
+  return DAG.getNode(X86ISD::SHUF128, DL, VT, V1, V2,
+                     DAG.getConstant(PermMask, DL, MVT::i8));
+}
+
 static SDValue lowerVectorShuffleWithPERMV(SDLoc DL, MVT VT,
                                            ArrayRef<int> Mask, SDValue V1,
                                            SDValue V2, SelectionDAG &DAG) {
@@ -10774,6 +10810,10 @@ static SDValue lowerV8F64VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
   ArrayRef<int> Mask = SVOp->getMask();
   assert(Mask.size() == 8 && "Unexpected mask size for v8 shuffle!");
 
+  if (SDValue Shuf128 =
+          lowerV4X128VectorShuffle(DL, MVT::v8f64, Mask, V1, V2, DAG))
+    return Shuf128;
+
   if (SDValue Unpck =
           lowerVectorShuffleWithUNPCK(DL, MVT::v8f64, Mask, V1, V2, DAG))
     return Unpck;
@@ -10810,6 +10850,10 @@ static SDValue lowerV8I64VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
   ArrayRef<int> Mask = SVOp->getMask();
   assert(Mask.size() == 8 && "Unexpected mask size for v8 shuffle!");
 
+  if (SDValue Shuf128 =
+          lowerV4X128VectorShuffle(DL, MVT::v8i64, Mask, V1, V2, DAG))
+    return Shuf128;
+
   if (SDValue Unpck =
           lowerVectorShuffleWithUNPCK(DL, MVT::v8i64, Mask, V1, V2, DAG))
     return Unpck;