Wrap MVT::ValueType in a struct to get type safety

and better control the abstraction.  Rename the type
to MVT.  To update out-of-tree patches, the main
thing to do is to rename MVT::ValueType to MVT, and
rewrite expressions like MVT::getSizeInBits(VT) in
the form VT.getSizeInBits().  Use VT.getSimpleVT()
to extract a MVT::SimpleValueType for use in switch
statements (you will get an assert failure if VT is
an extended value type - these shouldn't exist after
type legalization).
This results in a small speedup of codegen and no
new testsuite failures (x86-64 linux).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52044 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/SelectionDAGISel.h

@@ -55,7 +55,7 @@ public:
 
   virtual bool runOnFunction(Function &Fn);
 
-  unsigned MakeReg(MVT::ValueType VT);
+  unsigned MakeReg(MVT VT);
 
   virtual void EmitFunctionEntryCode(Function &Fn, MachineFunction &MF) {}
   virtual void InstructionSelectBasicBlock(SelectionDAG &SD) = 0;