Add immediate operands and arithmetic operations to the x64 assembler.

src/memory.h

 // Copyright 2006-2008 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 26 matching lines @@
 class Memory {
  public:
   static uint32_t& uint32_at(Address addr)  {
     return *reinterpret_cast<uint32_t*>(addr);
   }
 
   static int32_t& int32_at(Address addr)  {
     return *reinterpret_cast<int32_t*>(addr);
   }
 
+  static uint64_t& uint64_at(Address addr)  {
+    return *reinterpret_cast<uint64_t*>(addr);
+  }
+
   static int& int_at(Address addr)  {
     return *reinterpret_cast<int*>(addr);
   }
 
   static Address& Address_at(Address addr)  {
     return *reinterpret_cast<Address*>(addr);
   }
 
   static Object*& Object_at(Address addr)  {
     return *reinterpret_cast<Object**>(addr);
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_MEMORY_H_