Revert of Remove register index/code indirection

src/x64/macro-assembler-x64.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_X64_MACRO_ASSEMBLER_X64_H_
 #define V8_X64_MACRO_ASSEMBLER_X64_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/base/flags.h"
 #include "src/frames.h"
 #include "src/globals.h"
 #include "src/x64/frames-x64.h"
 
 namespace v8 {
 namespace internal {
 
 // Give alias names to registers for calling conventions.
-const Register kReturnRegister0 = {Register::kCode_rax};
-const Register kReturnRegister1 = {Register::kCode_rdx};
-const Register kJSFunctionRegister = {Register::kCode_rdi};
-const Register kContextRegister = {Register::kCode_rsi};
-const Register kInterpreterAccumulatorRegister = {Register::kCode_rax};
-const Register kInterpreterRegisterFileRegister = {Register::kCode_r11};
-const Register kInterpreterBytecodeOffsetRegister = {Register::kCode_r12};
-const Register kInterpreterBytecodeArrayRegister = {Register::kCode_r14};
-const Register kInterpreterDispatchTableRegister = {Register::kCode_r15};
-const Register kRuntimeCallFunctionRegister = {Register::kCode_rbx};
-const Register kRuntimeCallArgCountRegister = {Register::kCode_rax};
+const Register kReturnRegister0 = {kRegister_rax_Code};
+const Register kReturnRegister1 = {kRegister_rdx_Code};
+const Register kJSFunctionRegister = {kRegister_rdi_Code};
+const Register kContextRegister = {kRegister_rsi_Code};
+const Register kInterpreterAccumulatorRegister = {kRegister_rax_Code};
+const Register kInterpreterRegisterFileRegister = {kRegister_r11_Code};
+const Register kInterpreterBytecodeOffsetRegister = {kRegister_r12_Code};
+const Register kInterpreterBytecodeArrayRegister = {kRegister_r14_Code};
+const Register kInterpreterDispatchTableRegister = {kRegister_r15_Code};
+const Register kRuntimeCallFunctionRegister = {kRegister_rbx_Code};
+const Register kRuntimeCallArgCountRegister = {kRegister_rax_Code};
 
 // Default scratch register used by MacroAssembler (and other code that needs
 // a spare register). The register isn't callee save, and not used by the
 // function calling convention.
 const Register kScratchRegister = { 10 };      // r10.
 const Register kRootRegister = { 13 };         // r13 (callee save).
 // Actual value of root register is offset from the root array's start
 // to take advantage of negitive 8-bit displacement values.
 const int kRootRegisterBias = 128;
 
@@ skipping 1593 matching lines @@
     masm->popfq();                                                           \
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_