Remove comparison methods for MVT. The main cause

of apint codegen failure is the DAG combiner doing
the wrong thing because it was comparing MVT's using
< rather than comparing the number of bits.  Removing
the < method makes this mistake impossible to commit.
Instead, add helper methods for comparing bits and use
them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52098 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/CodeGenPrepare.cpp

@@ -339,10 +339,10 @@ static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI){
   // This is an fp<->int conversion?
   if (SrcVT.isInteger() != DstVT.isInteger())
     return false;
-  
+
   // If this is an extension, it will be a zero or sign extension, which
   // isn't a noop.
-  if (SrcVT < DstVT) return false;
+  if (SrcVT.bitsLT(DstVT)) return false;
   
   // If these values will be promoted, find out what they will be promoted
   // to.  This helps us consider truncates on PPC as noop copies when they