[X86][AVX2] Prefer VPERMQ/VPERMPD over VINSERTI128/VINSERTF128 for unary shuffles

Using VPERMQ/VPERMPD allows memory folding of the (repeated) input where VINSERTI128/VINSERTF128 can not.

Differential Revision: http://reviews.llvm.org/D19228

llvm-svn: 266728

1 files changed, 10 insertions, 4 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a9e5f1fdf44..2a0e83cda7a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -10586,6 +10586,10 @@ static SDValue lowerV2X128VectorShuffle(SDLoc DL, MVT VT, SDValue V1,
     // subvector.
     bool OnlyUsesV1 = isShuffleEquivalent(V1, V2, Mask, {0, 1, 0, 1});
     if (OnlyUsesV1 || isShuffleEquivalent(V1, V2, Mask, {0, 1, 4, 5})) {
+      // With AVX2 we should use VPERMQ/VPERMPD to allow memory folding.
+      if (Subtarget.hasAVX2() && isSingleInputShuffleMask(Mask))
+        return SDValue();
+
       MVT SubVT = MVT::getVectorVT(VT.getVectorElementType(),
                                    VT.getVectorNumElements() / 2);
       SDValue LoV = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, SubVT, V1,
@@ -11038,8 +11042,9 @@ static SDValue lowerV4F64VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
 
   SmallVector<int, 4> WidenedMask;
   if (canWidenShuffleElements(Mask, WidenedMask))
-    return lowerV2X128VectorShuffle(DL, MVT::v4f64, V1, V2, Mask, Subtarget,
-                                    DAG);
+    if (SDValue V = lowerV2X128VectorShuffle(DL, MVT::v4f64, V1, V2, Mask,
+                                             Subtarget, DAG))
+      return V;
 
   if (isSingleInputShuffleMask(Mask)) {
     // Check for being able to broadcast a single element.
@@ -11133,8 +11138,9 @@ static SDValue lowerV4I64VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
 
   SmallVector<int, 4> WidenedMask;
   if (canWidenShuffleElements(Mask, WidenedMask))
-    return lowerV2X128VectorShuffle(DL, MVT::v4i64, V1, V2, Mask, Subtarget,
-                                    DAG);
+    if (SDValue V = lowerV2X128VectorShuffle(DL, MVT::v4i64, V1, V2, Mask,
+                                             Subtarget, DAG))
+      return V;
 
   if (SDValue Blend = lowerVectorShuffleAsBlend(DL, MVT::v4i64, V1, V2, Mask,
                                                 Subtarget, DAG))