Change getTargetNodeName() to produce compiler warnings for missing cases, fix them

llvm-svn: 236775
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index 7e2ebd4..33cbb6e 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -24,7 +24,7 @@
 
 namespace llvm {
   namespace PPCISD {
-    enum NodeType {
+    enum NodeType : unsigned {
       // Start the numbering where the builtin ops and target ops leave off.
       FIRST_NUMBER = ISD::BUILTIN_OP_END,