Add comment to generated code that says which code generator compiled it.

src/x64/fast-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 170 matching lines @@
   // If we didn't bailout, the result (in fact, both inputs too) is known to
   // be a smi.
   set_as_smi(accumulator0());
   set_as_smi(accumulator1());
 }
 
 
 void FastCodeGenerator::Generate(CompilationInfo* compilation_info) {
   ASSERT(info_ == NULL);
   info_ = compilation_info;
+  Comment cmnt(masm_, "[ function compiled by fast code generator");
 
   // Save the caller's frame pointer and set up our own.
   Comment prologue_cmnt(masm(), ";; Prologue");
   __ push(rbp);
   __ movq(rbp, rsp);
   __ push(rsi);  // Context.
   __ push(rdi);  // Closure.
   // Note that we keep a live register reference to esi (context) at this
   // point.
 
@@ skipping 34 matching lines @@
   __ movq(rsp, rbp);
   __ pop(rbp);
   __ ret((scope()->num_parameters() + 1) * kPointerSize);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal