[heap] IncrementalMarking: Simplifiy MarkingWorklist handling

Bug: 
Change-Id: I0eb97474acaed7180bf90a47a9761df466d7e0a2
Reviewed-on: https://chromium-review.googlesource.com/716037Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48501}

src/heap/heap.cc

@@ -5383,10 +5383,9 @@ bool Heap::SetUp() {
   store_buffer_ = new StoreBuffer(this);
 
   mark_compact_collector_ = new MarkCompactCollector(this);
-  incremental_marking_ = new IncrementalMarking(this);
+  incremental_marking_ =
+      new IncrementalMarking(this, mark_compact_collector_->marking_worklist());
 
-  incremental_marking_->set_marking_worklist(
-      mark_compact_collector_->marking_worklist());
   if (FLAG_concurrent_marking) {
     MarkCompactCollector::MarkingWorklist* marking_worklist =
         mark_compact_collector_->marking_worklist();

src/heap/incremental-marking.cc

@@ -45,9 +45,10 @@ void IncrementalMarking::Observer::Step(int bytes_allocated, Address addr,
   }
 }
 
-IncrementalMarking::IncrementalMarking(Heap* heap)
+IncrementalMarking::IncrementalMarking(
+    Heap* heap, MarkCompactCollector::MarkingWorklist* marking_worklist)
     : heap_(heap),
-      marking_worklist_(nullptr),
+      marking_worklist_(marking_worklist),
       initial_old_generation_size_(0),
       bytes_marked_ahead_of_schedule_(0),
       unscanned_bytes_of_large_object_(0),
@@ -60,6 +61,7 @@ IncrementalMarking::IncrementalMarking(Heap* heap)
       request_type_(NONE),
       new_generation_observer_(*this, kYoungGenerationAllocatedThreshold),
       old_generation_observer_(*this, kOldGenerationAllocatedThreshold) {
+  DCHECK_NOT_NULL(marking_worklist_);
   SetState(STOPPED);
 }
 

src/heap/incremental-marking.h

@@ -107,7 +107,8 @@ class V8_EXPORT_PRIVATE IncrementalMarking {
   static const AccessMode kAtomicity = AccessMode::NON_ATOMIC;
 #endif
 
-  explicit IncrementalMarking(Heap* heap);
+  IncrementalMarking(Heap* heap,
+                     MarkCompactCollector::MarkingWorklist* marking_worklist);
 
   MarkingState* marking_state() { return &marking_state_; }
 
@@ -273,16 +274,10 @@ class V8_EXPORT_PRIVATE IncrementalMarking {
 
   void AbortBlackAllocation();
 
-  MarkCompactCollector::MarkingWorklist* marking_worklist() {
-    SLOW_DCHECK(marking_worklist_ != nullptr);
+  MarkCompactCollector::MarkingWorklist* marking_worklist() const {
     return marking_worklist_;
   }
 
-  void set_marking_worklist(
-      MarkCompactCollector::MarkingWorklist* marking_worklist) {
-    marking_worklist_ = marking_worklist;
-  }
-
   void Deactivate();
 
  private:
@@ -345,8 +340,8 @@ class V8_EXPORT_PRIVATE IncrementalMarking {
     heap_->SetIsMarkingFlag(s >= MARKING);
   }
 
-  Heap* heap_;
-  MarkCompactCollector::MarkingWorklist* marking_worklist_;
+  Heap* const heap_;
+  MarkCompactCollector::MarkingWorklist* const marking_worklist_;
 
   double start_time_ms_;
   size_t initial_old_generation_size_;