Reland "[heap] Introduce parallel compaction algorithm."

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include "src/base/bits.h"
 #include "src/heap/spaces.h"
 
@@ skipping 535 matching lines @@
 
   // True if concurrent or parallel sweeping is currently in progress.
   bool sweeping_in_progress_;
 
   // True if parallel compaction is currently in progress.
   bool parallel_compaction_in_progress_;
 
   // Synchronize sweeper threads.
   base::Semaphore pending_sweeper_jobs_semaphore_;
 
-  // Synchronize compaction threads.
-  base::Semaphore pending_compaction_jobs_semaphore_;
+  // Synchronize compaction tasks.
+  base::Semaphore pending_compaction_tasks_semaphore_;
+
+  // Number of active compaction tasks (including main thread).
+  intptr_t concurrent_compaction_tasks_active_;
 
   bool evacuation_;
 
   SlotsBufferAllocator* slots_buffer_allocator_;
 
   SlotsBuffer* migration_slots_buffer_;
 
   base::Mutex migration_slots_buffer_mutex_;
 
   // Finishes GC, performs heap verification if enabled.
@@ skipping 137 matching lines @@
   // If we are not compacting the heap, we simply sweep the spaces except
   // for the large object space, clearing mark bits and adding unmarked
   // regions to each space's free list.
   void SweepSpaces();
 
   int DiscoverAndEvacuateBlackObjectsOnPage(NewSpace* new_space,
                                             NewSpacePage* p);
 
   void EvacuateNewSpace();
 
-  void EvacuateLiveObjectsFromPage(Page* p, PagedSpace* target_space);
+  bool EvacuateLiveObjectsFromPage(Page* p, PagedSpace* target_space);
 
-  void EvacuatePages();
+  void EvacuatePages(CompactionSpaceCollection* compaction_spaces);
+  void EvacuatePagesInParallel();
 
-  void EvacuatePagesInParallel();
+  int NumberOfParallelCompactionTasks() {
+    // TODO(hpayer, mlippautz): Figure out some logic to determine the number
+    // of compaction tasks.
+    return 1;
+  }
 
   void WaitUntilCompactionCompleted();
 
   void EvacuateNewSpaceAndCandidates();
 
   void ReleaseEvacuationCandidates();
 
   // Moves the pages of the evacuation_candidates_ list to the end of their
   // corresponding space pages list.
   void MoveEvacuationCandidatesToEndOfPagesList();
@@ skipping 93 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_MARK_COMPACT_H_