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/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c7e055d..556aaac 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5640,7 +5640,7 @@
 //===----------------------------------------------------------------------===//
 
 void X86TargetLowering::computeMaskedBitsForTargetNode(const SDOperand Op,
-                                                       APInt Mask,
+                                                       const APInt &Mask,
                                                        APInt &KnownZero,
                                                        APInt &KnownOne,
                                                        const SelectionDAG &DAG,