Add an isAllOnesValue utility function, similar to isZero and isOne.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74032 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/ScalarEvolution.h

@@ -82,6 +82,11 @@ namespace llvm {
     ///
     bool isOne() const;
 
+    /// isAllOnesValue - Return true if the expression is a constant
+    /// all-ones value.
+    ///
+    bool isAllOnesValue() const;
+
     /// replaceSymbolicValuesWithConcrete - If this SCEV internally references
     /// the symbolic value "Sym", construct and return a new SCEV that produces
     /// the same value, but which uses the concrete value Conc instead of the