Replace the PointerLikeTypeTraits::getNumLowBitsAvailable

function with a new NumLowBitsAvailable enum, which makes the
value available as an integer constant expression.

Add PointerLikeTypeTraits specializations for Instruction* and
Use** since they are only guaranteed 4-byte aligned.

Enhance PointerIntPair to know about (and enforce) the alignment
specified by PointerLikeTypeTraits.  This should allow things 
like PointerIntPair<PointerIntPair<void*, 1,bool>, 1, bool> 
because the inner one knows that 2 low bits are free.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67979 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/PointerLikeTypeTraits.h

@@ -42,7 +42,7 @@ public:
   ///
   /// All clients should use assertions to do a run-time check to ensure that
   /// this is actually true.
-  static inline unsigned getNumLowBitsAvailable() { return 3; }
+  enum { NumLowBitsAvailable = 3 };
 };
   
 // Provide PointerLikeTypeTraits for const pointers.
@@ -53,7 +53,7 @@ public:
   static inline const T *getFromVoidPointer(const void *P) {
     return static_cast<const T*>(P);
   }
-  static inline unsigned getNumLowBitsAvailable() { return 3; }
+  enum { NumLowBitsAvailable = 3 };
 };
   
 } // end namespace llvm