Subzero: Refactor x86 register definitions to use the alias mechanism.

src/IceConditionCodesX8664.h

 //===- subzero/src/IceConditionCodesX8664.h - Condition Codes ---*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// This file declares the condition codes for x86-64.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICECONDITIONCODESX8664_H
 #define SUBZERO_SRC_ICECONDITIONCODESX8664_H
 
 #include "IceDefs.h"
 #include "IceInstX8664.def"
 
 namespace Ice {
 
 class CondX8664 {
 public:
   /// An enum of condition codes used for branches and cmov. The enum value
   /// should match the value used to encode operands in binary instructions.
   enum BrCond {
-#define X(tag, encode, opp, dump, emit) tag encode,
+#define X(val, encode, opp, dump, emit) val = encode,
     ICEINSTX8664BR_TABLE
 #undef X
         Br_None
   };
 
   /// An enum of condition codes relevant to the CMPPS instruction. The enum
   /// value should match the value used to encode operands in binary
   /// instructions.
   enum CmppsCond {
-#define X(tag, emit) tag,
+#define X(val, emit) val,
     ICEINSTX8664CMPPS_TABLE
 #undef X
         Cmpps_Invalid
   };
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECONDITIONCODESX8664_H