[X86][SSE] Minor regression fix for r225551

r225551 vector byte shuffle optimization caused an assertion as fully zeroable vectors can be produced under certain circumstances. This fix drops the assert and returns a zero vector where the assert would have failed.

llvm-svn: 225718

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f455700d5ad..c36bd52fc55 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -9652,7 +9652,6 @@ static SDValue lowerV16I8VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
         V2InUse |= (ZeroMask != V2Idx);
       }
     }
-    assert((V1InUse || V2InUse) && "Shuffling to a zeroable vector");
 
     if (V1InUse)
       V1 = DAG.getNode(X86ISD::PSHUFB, DL, MVT::v16i8, V1,
@@ -9668,6 +9667,8 @@ static SDValue lowerV16I8VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
       return V1; // Single inputs are easy.
     if (V2InUse)
       return V2; // Single inputs are easy.
+    // Shuffling to a zeroable vector.
+    return getZeroVector(MVT::v16i8, Subtarget, DAG, DL);
   }
 
   // There are special ways we can lower some single-element blends.