[llvm-commits] [llvm] r50368 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Dan Gohman]

Author: djg
Date: Mon Apr 28 13:47:17 2008
New Revision: 50368

URL: http://llvm.org/viewvc/llvm-project?rev=50368&view=rev
Log:
Evan pointed out that folding sext to zext may not be correct
if the zext is not legal.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=50368&r1=50367&r2=50368&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Apr 28 13:47:17 2008
@@ -2888,7 +2888,8 @@
   }
   
   // fold (sext x) -> (zext x) if the sign bit is known zero.
-  if (DAG.SignBitIsZero(N0))
+  if ((!AfterLegalize || TLI.isOperationLegal(ISD::ZERO_EXTEND, VT)) &&
+      DAG.SignBitIsZero(N0))
     return DAG.getNode(ISD::ZERO_EXTEND, VT, N0);
   
   return SDOperand();