Simplify some logic in ComputeMaskedBits. And change ComputeMaskedBits
to pass the mask APInt by value, not by reference. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47096 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 80ee51a..285a20d 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -106,7 +106,7 @@
                                             SelectionDAG &DAG);
 
     virtual void computeMaskedBitsForTargetNode(const SDOperand Op,
-                                                APInt Mask,
+                                                const APInt &Mask,
                                                 APInt &KnownZero, 
                                                 APInt &KnownOne,
                                                 const SelectionDAG &DAG,