Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/full-codegen.cc

 // Copyright 2012 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 396 matching lines @@
 void FullCodeGenerator::Initialize() {
   // The generation of debug code must match between the snapshot code and the
   // code that is generated later.  This is assumed by the debugger when it is
   // calculating PC offsets after generating a debug version of code.  Therefore
   // we disable the production of debug code in the full compiler if we are
   // either generating a snapshot or we booted from a snapshot.
   generate_debug_code_ = FLAG_debug_code &&
                          !Serializer::enabled() &&
                          !Snapshot::HaveASnapshotToStartFrom();
   masm_->set_emit_debug_code(generate_debug_code_);
+  masm_->set_emit_allocations_tracking_code(
+      masm_->isolate()->heap_profiler()->is_tracking_allocations());
   masm_->set_predictable_code_size(true);
   InitializeAstVisitor(info_->isolate());
 }
 
 
 void FullCodeGenerator::PopulateTypeFeedbackCells(Handle<Code> code) {
   if (type_feedback_cells_.is_empty()) return;
   int length = type_feedback_cells_.length();
   int array_size = TypeFeedbackCells::LengthOfFixedArray(length);
   Handle<TypeFeedbackCells> cache = Handle<TypeFeedbackCells>::cast(
@@ skipping 1258 matching lines @@
   }
   return true;
 }
 #endif  // DEBUG
 
 
 #undef __
 
 
 } }  // namespace v8::internal