Convert MaskedValueIsZero and all its users to use APInt. Also add
a SignBitIsZero function to simplify a common use case.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47561 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
index d1e1311..b0ca39b 100644
--- a/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
+++ b/lib/Target/Alpha/AlphaISelDAGToDAG.cpp
@@ -91,7 +91,9 @@
       // see if the missing bits (0x1000) are already known zero if not, the zap
       // isn't okay to do, as it won't clear all the required bits.
       if (BitsToCheck &&
-          !CurDAG->MaskedValueIsZero(LHS, BitsToCheck))
+          !CurDAG->MaskedValueIsZero(LHS,
+                                     APInt(LHS.getValueSizeInBits(),
+                                           BitsToCheck)))
         return 0;
       
       return Result;