[x86] Teach the new vector shuffle lowering to use VPERMILPD for

single-input shuffles with doubles. This allows them to fold memory
operands into the shuffle, etc. This is just the analog to the v4f32
case in my prior commit.

llvm-svn: 218193

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 29b9effad73..654a1abf710 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -7657,6 +7657,14 @@ static SDValue lowerV2F64VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
     // Straight shuffle of a single input vector. Simulate this by using the
     // single input as both of the "inputs" to this instruction..
     unsigned SHUFPDMask = (Mask[0] == 1) | ((Mask[1] == 1) << 1);
+
+    if (Subtarget->hasAVX()) {
+      // If we have AVX, we can use VPERMILPS which will allow folding a load
+      // into the shuffle.
+      return DAG.getNode(X86ISD::VPERMILP, DL, MVT::v2f64, V1,
+                         DAG.getConstant(SHUFPDMask, MVT::i8));
+    }
+
     return DAG.getNode(X86ISD::SHUFP, SDLoc(Op), MVT::v2f64, V1, V1,
                        DAG.getConstant(SHUFPDMask, MVT::i8));
   }