[x86] Teach the new vector shuffle lowering to use the AVX VPERMILPS

[oota-llvm.git] / lib / Target / X86 / X86ISelLowering.cpp

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 6ffda166ed209c11d4debe5af9ef0af19c4ff930..29b9effad731c951dc781f4db6598c9b55e7a001 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -7772,11 +7772,19 @@ static SDValue lowerV4F32VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
   int NumV2Elements =
       std::count_if(Mask.begin(), Mask.end(), [](int M) { return M >= 4; });
 
-  if (NumV2Elements == 0)
-    // Straight shuffle of a single input vector. We pass the input vector to
-    // both operands to simulate this with a SHUFPS.
+  if (NumV2Elements == 0) {
+    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::v4f32, V1,
+                         getV4X86ShuffleImm8ForMask(Mask, DAG));
+    }
+
+    // Otherwise, use a straight shuffle of a single input vector. We pass the
+    // input vector to both operands to simulate this with a SHUFPS.
     return DAG.getNode(X86ISD::SHUFP, DL, MVT::v4f32, V1, V1,
                        getV4X86ShuffleImm8ForMask(Mask, DAG));
+  }
 
   // Use dedicated unpack instructions for masks that match their pattern.
   if (isShuffleEquivalent(Mask, 0, 4, 1, 5))