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diff --git a/deps/v8/src/heap/incremental-marking.h b/deps/v8/src/heap/incremental-marking.h
new file mode 100644
index 000000000..c054fbd40
--- /dev/null
+++ b/deps/v8/src/heap/incremental-marking.h
@@ -0,0 +1,222 @@
+// 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_INCREMENTAL_MARKING_H_
+#define V8_HEAP_INCREMENTAL_MARKING_H_
+
+
+#include "src/execution.h"
+#include "src/heap/mark-compact.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+
+
+class IncrementalMarking {
+ public:
+  enum State { STOPPED, SWEEPING, MARKING, COMPLETE };
+
+  enum CompletionAction { GC_VIA_STACK_GUARD, NO_GC_VIA_STACK_GUARD };
+
+  explicit IncrementalMarking(Heap* heap);
+
+  static void Initialize();
+
+  void TearDown();
+
+  State state() {
+    DCHECK(state_ == STOPPED || FLAG_incremental_marking);
+    return state_;
+  }
+
+  bool should_hurry() { return should_hurry_; }
+  void set_should_hurry(bool val) { should_hurry_ = val; }
+
+  inline bool IsStopped() { return state() == STOPPED; }
+
+  INLINE(bool IsMarking()) { return state() >= MARKING; }
+
+  inline bool IsMarkingIncomplete() { return state() == MARKING; }
+
+  inline bool IsComplete() { return state() == COMPLETE; }
+
+  bool WorthActivating();
+
+  enum CompactionFlag { ALLOW_COMPACTION, PREVENT_COMPACTION };
+
+  void Start(CompactionFlag flag = ALLOW_COMPACTION);
+
+  void Stop();
+
+  void PrepareForScavenge();
+
+  void UpdateMarkingDequeAfterScavenge();
+
+  void Hurry();
+
+  void Finalize();
+
+  void Abort();
+
+  void MarkingComplete(CompletionAction action);
+
+  // It's hard to know how much work the incremental marker should do to make
+  // progress in the face of the mutator creating new work for it.  We start
+  // of at a moderate rate of work and gradually increase the speed of the
+  // incremental marker until it completes.
+  // Do some marking every time this much memory has been allocated or that many
+  // heavy (color-checking) write barriers have been invoked.
+  static const intptr_t kAllocatedThreshold = 65536;
+  static const intptr_t kWriteBarriersInvokedThreshold = 32768;
+  // Start off by marking this many times more memory than has been allocated.
+  static const intptr_t kInitialMarkingSpeed = 1;
+  // But if we are promoting a lot of data we need to mark faster to keep up
+  // with the data that is entering the old space through promotion.
+  static const intptr_t kFastMarking = 3;
+  // After this many steps we increase the marking/allocating factor.
+  static const intptr_t kMarkingSpeedAccellerationInterval = 1024;
+  // This is how much we increase the marking/allocating factor by.
+  static const intptr_t kMarkingSpeedAccelleration = 2;
+  static const intptr_t kMaxMarkingSpeed = 1000;
+
+  void OldSpaceStep(intptr_t allocated);
+
+  void Step(intptr_t allocated, CompletionAction action,
+            bool force_marking = false);
+
+  inline void RestartIfNotMarking() {
+    if (state_ == COMPLETE) {
+      state_ = MARKING;
+      if (FLAG_trace_incremental_marking) {
+        PrintF("[IncrementalMarking] Restarting (new grey objects)\n");
+      }
+    }
+  }
+
+  static void RecordWriteFromCode(HeapObject* obj, Object** slot,
+                                  Isolate* isolate);
+
+  // Record a slot for compaction.  Returns false for objects that are
+  // guaranteed to be rescanned or not guaranteed to survive.
+  //
+  // No slots in white objects should be recorded, as some slots are typed and
+  // cannot be interpreted correctly if the underlying object does not survive
+  // the incremental cycle (stays white).
+  INLINE(bool BaseRecordWrite(HeapObject* obj, Object** slot, Object* value));
+  INLINE(void RecordWrite(HeapObject* obj, Object** slot, Object* value));
+  INLINE(void RecordWriteIntoCode(HeapObject* obj, RelocInfo* rinfo,
+                                  Object* value));
+  INLINE(void RecordWriteOfCodeEntry(JSFunction* host, Object** slot,
+                                     Code* value));
+
+
+  void RecordWriteSlow(HeapObject* obj, Object** slot, Object* value);
+  void RecordWriteIntoCodeSlow(HeapObject* obj, RelocInfo* rinfo,
+                               Object* value);
+  void RecordWriteOfCodeEntrySlow(JSFunction* host, Object** slot, Code* value);
+  void RecordCodeTargetPatch(Code* host, Address pc, HeapObject* value);
+  void RecordCodeTargetPatch(Address pc, HeapObject* value);
+
+  inline void RecordWrites(HeapObject* obj);
+
+  inline void BlackToGreyAndUnshift(HeapObject* obj, MarkBit mark_bit);
+
+  inline void WhiteToGreyAndPush(HeapObject* obj, MarkBit mark_bit);
+
+  inline void SetOldSpacePageFlags(MemoryChunk* chunk) {
+    SetOldSpacePageFlags(chunk, IsMarking(), IsCompacting());
+  }
+
+  inline void SetNewSpacePageFlags(NewSpacePage* chunk) {
+    SetNewSpacePageFlags(chunk, IsMarking());
+  }
+
+  MarkingDeque* marking_deque() { return &marking_deque_; }
+
+  bool IsCompacting() { return IsMarking() && is_compacting_; }
+
+  void ActivateGeneratedStub(Code* stub);
+
+  void NotifyOfHighPromotionRate() {
+    if (IsMarking()) {
+      if (marking_speed_ < kFastMarking) {
+        if (FLAG_trace_gc) {
+          PrintPID(
+              "Increasing marking speed to %d "
+              "due to high promotion rate\n",
+              static_cast<int>(kFastMarking));
+        }
+        marking_speed_ = kFastMarking;
+      }
+    }
+  }
+
+  void EnterNoMarkingScope() { no_marking_scope_depth_++; }
+
+  void LeaveNoMarkingScope() { no_marking_scope_depth_--; }
+
+  void UncommitMarkingDeque();
+
+  void NotifyIncompleteScanOfObject(int unscanned_bytes) {
+    unscanned_bytes_of_large_object_ = unscanned_bytes;
+  }
+
+ private:
+  int64_t SpaceLeftInOldSpace();
+
+  void ResetStepCounters();
+
+  void StartMarking(CompactionFlag flag);
+
+  void ActivateIncrementalWriteBarrier(PagedSpace* space);
+  static void ActivateIncrementalWriteBarrier(NewSpace* space);
+  void ActivateIncrementalWriteBarrier();
+
+  static void DeactivateIncrementalWriteBarrierForSpace(PagedSpace* space);
+  static void DeactivateIncrementalWriteBarrierForSpace(NewSpace* space);
+  void DeactivateIncrementalWriteBarrier();
+
+  static void SetOldSpacePageFlags(MemoryChunk* chunk, bool is_marking,
+                                   bool is_compacting);
+
+  static void SetNewSpacePageFlags(NewSpacePage* chunk, bool is_marking);
+
+  void EnsureMarkingDequeIsCommitted();
+
+  INLINE(void ProcessMarkingDeque());
+
+  INLINE(intptr_t ProcessMarkingDeque(intptr_t bytes_to_process));
+
+  INLINE(void VisitObject(Map* map, HeapObject* obj, int size));
+
+  Heap* heap_;
+
+  State state_;
+  bool is_compacting_;
+
+  base::VirtualMemory* marking_deque_memory_;
+  bool marking_deque_memory_committed_;
+  MarkingDeque marking_deque_;
+
+  int steps_count_;
+  int64_t old_generation_space_available_at_start_of_incremental_;
+  int64_t old_generation_space_used_at_start_of_incremental_;
+  int64_t bytes_rescanned_;
+  bool should_hurry_;
+  int marking_speed_;
+  intptr_t bytes_scanned_;
+  intptr_t allocated_;
+  intptr_t write_barriers_invoked_since_last_step_;
+
+  int no_marking_scope_depth_;
+
+  int unscanned_bytes_of_large_object_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
+};
+}
+}  // namespace v8::internal
+
+#endif  // V8_HEAP_INCREMENTAL_MARKING_H_