[llvm] r321463 - [X86] Return SDValue(N, 0) instead of an SDValue() after a successful combine.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Tue Dec 26 14:22:58 2017
New Revision: 321463

URL: http://llvm.org/viewvc/llvm-project?rev=321463&view=rev
Log:
[X86] Return SDValue(N, 0) instead of an SDValue() after a successful combine.

Returning SDValue() means nothing changed, SDValue(N,0) means there was a change but the worklist management was taken care of.

I don't know if this has a real effect other than making sure the combine counter in the DAG combiner gets updated, but it is the correct thing to do.

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=321463&r1=321462&r2=321463&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue Dec 26 14:22:58 2017
@@ -31003,8 +31003,8 @@ static SDValue combineExtractVectorElt(S
     DAG.ReplaceAllUsesOfValueWith(SDValue(Extract, 0), Vals[IdxVal]);
   }
 
-  // The replacement was made in place; don't return anything.
-  return SDValue();
+  // The replacement was made in place; return N so it won't be revisited.
+  return SDValue(N, 0);
 }
 
 /// If a vector select has an operand that is -1 or 0, try to simplify the