[heap] MC: Refactor page evacuation

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index e4acac031a5d045adc7e70098d4e55770e96af20..c1ab317d25ba7a841ac9f92765702e874a4da9da 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -415,6 +415,12 @@ enum PageEvacuationMode { NEW_TO_NEW, NEW_TO_OLD };
 class MarkCompactCollectorBase {
  public:
   virtual ~MarkCompactCollectorBase() {}
+
+  // Note: Make sure to refer to the instances by their concrete collector
+  // type to avoid vtable lookups marking state methods when used in hot paths.
+  virtual MarkingState marking_state(HeapObject* object) const = 0;
+  virtual MarkingState marking_state(MemoryChunk* chunk) const = 0;
+
   virtual void SetUp() = 0;
   virtual void TearDown() = 0;
   virtual void CollectGarbage() = 0;
@@ -439,6 +445,14 @@ class MinorMarkCompactCollector final : public MarkCompactCollectorBase {
   explicit MinorMarkCompactCollector(Heap* heap)
       : MarkCompactCollectorBase(heap), marking_deque_(heap) {}
 
+  MarkingState marking_state(HeapObject* object) const override {
+    return MarkingState::External(object);
+  }
+
+  MarkingState marking_state(MemoryChunk* chunk) const override {
+    return MarkingState::External(chunk);
+  }
+
   void SetUp() override;
   void TearDown() override;
   void CollectGarbage() override;
@@ -549,6 +563,14 @@ class MarkCompactCollector final : public MarkCompactCollectorBase {
 
   static void Initialize();
 
+  MarkingState marking_state(HeapObject* object) const override {
+    return MarkingState::Internal(object);

[Michael Lippautz, 2017/04/25 14:14:37]

These should be the only getters that know about the internal/external state. I
will incrementally replace the uses in mark-compact.cc

+  }
+
+  MarkingState marking_state(MemoryChunk* chunk) const override {
+    return MarkingState::Internal(chunk);
+  }
+
   void SetUp() override;
   void TearDown() override;
   // Performs a global garbage collection.