Inform the dag combiner that the predicate compares only return a low bit.

llvm-svn: 27359
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index bc865c6..2fe79ec 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -133,6 +133,11 @@
     
     virtual SDOperand PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
 
+    virtual void computeMaskedBitsForTargetNode(const SDOperand Op,
+                                                uint64_t Mask,
+                                                uint64_t &KnownZero, 
+                                                uint64_t &KnownOne,
+                                                unsigned Depth = 0) const;
     /// LowerArguments - This hook must be implemented to indicate how we should
     /// lower the arguments for the specified function, into the specified DAG.
     virtual std::vector<SDOperand>