Introduce --job-based-sweeping flag and use individual jobs for sweeping if set

src/heap.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 6361 matching lines @@
       + old_data_space_->SizeOfObjects()
       + code_space_->SizeOfObjects()
       + map_space_->SizeOfObjects()
       + cell_space_->SizeOfObjects()
       + property_cell_space_->SizeOfObjects()
       + lo_space_->SizeOfObjects();
 }
 
 
 bool Heap::AdvanceSweepers(int step_size) {
-  ASSERT(isolate()->num_sweeper_threads() == 0);
+  ASSERT(!mark_compact_collector()->AreSweeperThreadsActivated());
   bool sweeping_complete = old_data_space()->AdvanceSweeper(step_size);
   sweeping_complete &= old_pointer_space()->AdvanceSweeper(step_size);
   return sweeping_complete;
 }
 
 
 int64_t Heap::PromotedExternalMemorySize() {
   if (amount_of_external_allocated_memory_
       <= amount_of_external_allocated_memory_at_last_global_gc_) return 0;
   return amount_of_external_allocated_memory_
@@ skipping 1346 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   OS::MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   OS::MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal