[AVX512] Add support for lowering to 512-bit SHUFPS.

llvm-svn: 275011

1 files changed, 8 insertions, 4 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 83e910d4f14..1bdb762a4b7 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -11821,11 +11821,15 @@ static SDValue lowerV16F32VectorShuffle(SDLoc DL, ArrayRef<int> Mask,
     if (V2.isUndef())
       return DAG.getNode(X86ISD::VPERMILPI, DL, MVT::v16f32, V1,
                          getV4X86ShuffleImm8ForMask(RepeatedMask, DL, DAG));
-  }
 
-  if (SDValue Unpck =
-          lowerVectorShuffleWithUNPCK(DL, MVT::v16f32, Mask, V1, V2, DAG))
-    return Unpck;
+    // Use dedicated unpack instructions for masks that match their pattern.
+    if (SDValue Unpck =
+            lowerVectorShuffleWithUNPCK(DL, MVT::v16f32, Mask, V1, V2, DAG))
+      return Unpck;
+
+    // Otherwise, fall back to a SHUFPS sequence.
+    return lowerVectorShuffleWithSHUFPS(DL, MVT::v16f32, RepeatedMask, V1, V2, DAG);
+  }
 
   return lowerVectorShuffleWithPERMV(DL, MVT::v16f32, Mask, V1, V2, DAG);
 }