Parallelize marking phase of mark-sweep/compact collection cycle.

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index 72a6fa3b624092cea830bedd7230e673f8844a23..0f7b477eb50daf0f882d83df43f1a0e9b9620036 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -39,8 +39,10 @@ typedef bool (*IsAliveFunction)(HeapObject* obj, int* size, int* offset);
 // Forward declarations.
 class RootMarkingVisitor;
 class MarkingVisitor;
+class Marker;
 
-
+// ----------------------------------------------------------------------------
+// Marking stack for tracing live objects.
 // -------------------------------------------------------------------------
 // Mark-Compact collector
 //
@@ -101,10 +103,6 @@ class MarkCompactCollector: public AllStatic {
 #endif
   }
 
-  // The count of the number of objects left marked at the end of the last
-  // completed full GC (expected to be zero).
-  static int previous_marked_count() { return previous_marked_count_; }
-
   // During a full GC, there is a stack-allocated GCTracer that is used for
   // bookkeeping information.  Return a pointer to that tracer.
   static GCTracer* tracer() { return tracer_; }
@@ -148,10 +146,6 @@ class MarkCompactCollector: public AllStatic {
   // Global flag indicating whether spaces will be compacted on the next GC.
   static bool compact_on_next_gc_;
 
-  // The number of objects left marked at the end of the last completed full
-  // GC (expected to be zero).
-  static int previous_marked_count_;
-
   // A pointer to the current stack-allocated GC tracer object during a full
   // collection (NULL before and after).
   static GCTracer* tracer_;
@@ -174,25 +168,28 @@ class MarkCompactCollector: public AllStatic {
   friend class StaticMarkingVisitor;
   friend class CodeMarkingVisitor;
   friend class SharedFunctionInfoMarkingVisitor;
+  friend class Marker;
 
   static void PrepareForCodeFlushing();
 
-  // Marking operations for objects reachable from roots.
-  static void MarkLiveObjects();
-
-  static void MarkUnmarkedObject(HeapObject* obj);
+  // Return total number of markers that will be used during
+  // marking phase.
+  static int NumberOfMarkers() {
+    // If parallel marking is enabled and atomic operations is supported
+    // on this platform use FLAG_number_of_markers otherwise use only
+    // main marker.
+#if ATOMIC_SUPPORTED
+    if (FLAG_parallel_marking) {
+      return 1 + FLAG_number_of_markers;
+    }
+#endif
 
-  static inline void MarkObject(HeapObject* obj) {
-    if (!obj->IsMarked()) MarkUnmarkedObject(obj);
+    return 1;
   }
 
-  static inline void SetMark(HeapObject* obj) {
-    tracer_->increment_marked_count();
-#ifdef DEBUG
-    UpdateLiveObjectCount(obj);
-#endif
-    obj->SetMark();
-  }
+
+  // Marking operations for objects reachable from roots.
+  static void MarkLiveObjects();
 
   // Creates back pointers for all map transitions, stores them in
   // the prototype field.  The original prototype pointers are restored
@@ -202,15 +199,16 @@ class MarkCompactCollector: public AllStatic {
   static void CreateBackPointers();
 
   // Mark a Map and its DescriptorArray together, skipping transitions.
-  static void MarkMapContents(Map* map);
-  static void MarkDescriptorArray(DescriptorArray* descriptors);
+  static void MarkMapContents(Map* map, Marker* marker);
+
+  static void MarkDescriptorArray(DescriptorArray* descriptors, Marker* marker);
 
   // Mark the heap roots and all objects reachable from them.
-  static void MarkRoots(RootMarkingVisitor* visitor);
+  static void MarkRoots();
 
   // Mark the symbol table specially.  References to symbols from the
   // symbol table are weak.
-  static void MarkSymbolTable();
+  static void MarkSymbolTable(Marker* marker);
 
   // Mark objects in object groups that have at least one object in the
   // group marked.
@@ -221,21 +219,6 @@ class MarkCompactCollector: public AllStatic {
   // groups, and repeat.
   static void ProcessObjectGroups();
 
-  // Mark objects reachable (transitively) from objects in the marking stack
-  // or overflowed in the heap.
-  static void ProcessMarkingStack();
-
-  // Mark objects reachable (transitively) from objects in the marking
-  // stack.  This function empties the marking stack, but may leave
-  // overflowed objects in the heap, in which case the marking stack's
-  // overflow flag will be set.
-  static void EmptyMarkingStack();
-
-  // Refill the marking stack with overflowed objects from the heap.  This
-  // function either leaves the marking stack full or clears the overflow
-  // flag on the marking stack.
-  static void RefillMarkingStack();
-
   // Callback function for telling whether the object *p is an unmarked
   // heap object.
   static bool IsUnmarkedHeapObject(Object** p);