[llvm] r225718 - [X86][SSE] Minor regression fix for r225551

[Simon Pilgrim]

Author: rksimon
Date: Mon Jan 12 16:38:08 2015
New Revision: 225718

URL: http://llvm.org/viewvc/llvm-project?rev=225718&view=rev
Log:
[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.


Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=225718&r1=225717&r2=225718&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Jan 12 16:38:08 2015
@@ -9652,7 +9652,6 @@ static SDValue lowerV16I8VectorShuffle(S
         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(S
       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.