Make all unnamed RegisterClass TreePatternNodes typed MVT::i32.

A register class can appear as a leaf TreePatternNode with and without a
name:

  (COPY_TO_REGCLASS GPR:$src, F8RC)

In a named leaf node like GPR:$src, the register class provides type
information for the named variable represented by the node. The TypeSet
for such a node is the set of value types that the register class can
represent.

In an unnamed leaf node like F8RC above, the register class represents
itself as a kind of immediate. Such a node has the type MVT::i32,
we'll never create a virtual register representing it.

This change makes it possible to remove the special handling of
COPY_TO_REGCLASS in CodeGenDAGPatterns.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177825 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenDAGPatterns.h b/utils/TableGen/CodeGenDAGPatterns.h
index 6190798..7c2fa36 100644
--- a/utils/TableGen/CodeGenDAGPatterns.h
+++ b/utils/TableGen/CodeGenDAGPatterns.h
@@ -334,6 +334,7 @@
   }
   ~TreePatternNode();
 
+  bool hasName() const { return !Name.empty(); }
   const std::string &getName() const { return Name; }
   void setName(StringRef N) { Name.assign(N.begin(), N.end()); }