Allow the optimizing compiler to use an existing macro assembler....

src/x64/codegen-x64.cc

 // Copyright 2010 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 228 matching lines @@
   // and rcx.
   static void LoadAsIntegers(MacroAssembler* masm,
                              bool use_sse3,
                              Label* operand_conversion_failure);
 };
 
 
 // -----------------------------------------------------------------------------
 // CodeGenerator implementation.
 
-CodeGenerator::CodeGenerator(int buffer_size,
+CodeGenerator::CodeGenerator(MacroAssembler* masm,
                              Handle<Script> script,
                              bool is_eval)
     : is_eval_(is_eval),
       script_(script),
       deferred_(8),
-      masm_(new MacroAssembler(NULL, buffer_size)),
+      masm_(masm),
       scope_(NULL),
       frame_(NULL),
       allocator_(NULL),
       state_(NULL),
       loop_nesting_(0),
       function_return_is_shadowed_(false),
       in_spilled_code_(false) {
 }
 
 
@@ skipping 8941 matching lines @@
   // Call the function from C++.
   return FUNCTION_CAST<ModuloFunction>(buffer);
 }
 
 #endif
 
 
 #undef __
 
 } }  // namespace v8::internal