--- old/src/share/vm/opto/opcodes.hpp	2016-07-11 22:46:48.197371491 +0900
+++ new/src/share/vm/opto/opcodes.hpp	2016-07-11 22:46:48.050372005 +0900
@@ -27,7 +27,7 @@
 
 // Build a big enum of class names to give them dense integer indices
 #define macro(x) Op_##x,
-enum Opcodes {
+enum class Opcodes : uint {
   Op_Node = 0,
   macro(Set)                    // Instruction selection match rule
   macro(RegN)                   // Machine narrow oop register
@@ -44,7 +44,11 @@
   macro(RegFlags)               // Machine flags   register
   _last_machine_leaf,           // Split between regular opcodes and machine
 #include "classes.hpp"
-  _last_opcode
+  _last_opcode,
+
+  NotAMachineReg = 0xffff0000,  // Arena we are currently building Nodes in
+
+  MaxVal = 0xffffffff
 };
 #undef macro