Use uniqued StringInit pointers for lookups.

This avoids a gazillion StringMap and dynamic_cast calls, making
TableGen run 3x faster.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148091 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/TableGen/TGParser.cpp b/lib/TableGen/TGParser.cpp
index 8bcb029..5c13af1 100644
--- a/lib/TableGen/TGParser.cpp
+++ b/lib/TableGen/TGParser.cpp
@@ -64,7 +64,7 @@
   if (CurRec == 0)
     CurRec = &CurMultiClass->Rec;
 
-  if (RecordVal *ERV = CurRec->getValue(RV.getName())) {
+  if (RecordVal *ERV = CurRec->getValue(RV.getNameInit())) {
     // The value already exists in the class, treat this as a set.
     if (ERV->setValue(RV.getValue()))
       return Error(Loc, "New definition of '" + RV.getName() + "' of type '" +