Optimize functions on a second thread.

src/heap.h

 // 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 1602 matching lines @@
       if (type == CODE_TYPE) {
         ASSERT(sub_type <= Code::LAST_CODE_KIND);
         object_counts_[FIRST_CODE_KIND_SUB_TYPE + sub_type]++;
         object_sizes_[FIRST_CODE_KIND_SUB_TYPE + sub_type] += size;
       }
     }
   }
 
   void CheckpointObjectStats();
 
+  // We don't use a ScopedLock here since we want to lock the heap
+  // only when FLAG_parallel_recompilation is true.
+  class RelocationLock {
+   public:
+    explicit RelocationLock(Heap* heap) : heap_(heap) {
+      if (FLAG_parallel_recompilation) {
+        heap_->relocation_mutex_->Lock();
+      }
+    }
+    ~RelocationLock() {
+      if (FLAG_parallel_recompilation) {
+        heap_->relocation_mutex_->Unlock();
+      }
+    }
+
+   private:
+    Heap* heap_;
+  };
+
  private:
   Heap();
 
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.
   Isolate* isolate_;
 
   Object* roots_[kRootListLength];
 
   intptr_t code_range_size_;
@@ skipping 432 matching lines @@
   // Flag is set when the heap has been configured.  The heap can be repeatedly
   // configured through the API until it is set up.
   bool configured_;
 
   ExternalStringTable external_string_table_;
 
   VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_;
 
   MemoryChunk* chunks_queued_for_free_;
 
+  Mutex* relocation_mutex_;
+
   friend class Factory;
   friend class GCTracer;
   friend class DisallowAllocationFailure;
   friend class AlwaysAllocateScope;
   friend class LinearAllocationScope;
   friend class Page;
   friend class Isolate;
   friend class MarkCompactCollector;
   friend class StaticMarkingVisitor;
   friend class MapCompact;
@@ skipping 643 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_