X64 implementation starts using virtual frame and register allocators.

src/x64/virtual-frame-x64.h

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 354 matching lines @@
   // Duplicate the top element of the frame.
   void Dup() { PushFrameSlotAt(element_count() - 1); }
 
   // Pop an element from the top of the expression stack.  Returns a
   // Result, which may be a constant or a register.
   Result Pop();
 
   // Pop and save an element from the top of the expression stack and
   // emit a corresponding pop instruction.
   void EmitPop(Register reg);
-  void EmitPop(Operand operand);
+  void EmitPop(const Operand& operand);
 
   // Push an element on top of the expression stack and emit a
   // corresponding push instruction.
   void EmitPush(Register reg);
-  void EmitPush(Operand operand);
+  void EmitPush(const Operand& operand);
   void EmitPush(Immediate immediate);
 
   // Push an element on the virtual frame.
   void Push(Register reg, StaticType static_type = StaticType());
   void Push(Handle<Object> value);
   void Push(Smi* value) { Push(Handle<Object>(value)); }
 
   // Pushing a result invalidates it (its contents become owned by the
   // frame).
   void Push(Result* result) {
@@ skipping 156 matching lines @@
 
   // Classes that need raw access to the elements_ array.
   friend class DeferredCode;
   friend class JumpTarget;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_VIRTUAL_FRAME_X64_H_