Separate markbits from heap object map words into bitmaps.

src/mark-compact.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 23 matching lines @@
 // Callback function, returns whether an object is alive. The heap size
 // of the object is returned in size. It optionally updates the offset
 // to the first live object in the page (only used for old and map objects).
 typedef bool (*IsAliveFunction)(HeapObject* obj, int* size, int* offset);
 
 // Forward declarations.
 class RootMarkingVisitor;
 class MarkingVisitor;
 
 
+class Marking {
+ public:
+  INLINE(static bool IsMarked(HeapObject* obj)) {
+    return IsMarked(obj->address());
+  }
+
+  INLINE(static void SetMark(HeapObject* obj)) {
+    SetMark(obj->address());
+  }
+
+  INLINE(static void ClearMark(HeapObject* obj)) {
+    ClearMark(obj->address());
+  }
+
+  INLINE(static bool TestAndMark(Address addr)) {
+    if (Heap::InNewSpace(addr)) {
+      uint32_t index = Heap::new_space()->Address2MarkbitIndex(addr);
+      return new_space_bitmap_->TestAndSet(index);
+    } else {
+      Page *p = Page::FromAddress(addr);
+      return p->markbits()->TestAndSet(p->Address2Markbit(addr));
+    }
+  }
+
+  INLINE(static bool IsMarked(Address addr)) {
+    if (Heap::InNewSpace(addr)) {
+      uint32_t index = Heap::new_space()->Address2MarkbitIndex(addr);
+      return new_space_bitmap_->Get(index);
+    } else {
+      Page *p = Page::FromAddress(addr);
+      return p->markbits()->Get(p->Address2Markbit(addr));
+    }
+  }
+
+  INLINE(static void SetMark(Address addr)) {
+    if (Heap::InNewSpace(addr)) {
+      uint32_t index = Heap::new_space()->Address2MarkbitIndex(addr);
+      new_space_bitmap_->Set(index, true);
+    } else {
+      Page *p = Page::FromAddress(addr);
+      p->markbits()->Set(p->FastAddress2Markbit(addr), true);
+    }
+  }
+
+  INLINE(static void ClearMark(Address addr)) {
+    if (Heap::InNewSpace(addr)) {
+      uint32_t index = Heap::new_space()->Address2MarkbitIndex(addr);
+      new_space_bitmap_->Set(index, false);
+    } else {
+      Page *p = Page::FromAddress(addr);
+      p->markbits()->Set(p->FastAddress2Markbit(addr), false);
+    }
+  }
+
+  INLINE(static void ClearRange(Address addr, int size)) {
+    if (Heap::InNewSpace(addr)) {
+      uint32_t index = Heap::new_space()->Address2MarkbitIndex(addr);
+      new_space_bitmap_->ClearRange(index, size >> kPointerSizeLog2);
+    } else {
+      Page *p = Page::FromAddress(addr);
+      p->markbits()->ClearRange(p->FastAddress2Markbit(addr),
+                                size >> kPointerSizeLog2);
+    }
+  }
+
+  static bool Setup();
+
+  static void TearDown();
+
+ private:
+  class BitmapStorageDescriptor {
+   public:
+    INLINE(static int CellsCount(Address addr)) {
+      return HeaderOf(addr)->cells_count_;
+    }
+
+    static Bitmap<BitmapStorageDescriptor>* Allocate(int cells_count) {
+      VirtualMemory* memory = new VirtualMemory(SizeFor(cells_count));
+
+      if (!memory->Commit(memory->address(), memory->size(), false)) {
+        delete memory;
+        return NULL;
+      }
+
+      Address bitmap_address =
+          reinterpret_cast<Address>(memory->address()) + sizeof(Header);
+      HeaderOf(bitmap_address)->cells_count_ = cells_count;
+      HeaderOf(bitmap_address)->storage_ = memory;
+      return Bitmap<BitmapStorageDescriptor>::FromAddress(bitmap_address);
+    }
+
+    static void Free(Bitmap<BitmapStorageDescriptor>* bitmap) {
+      delete HeaderOf(bitmap->address())->storage_;
+    }
+
+   private:
+    struct Header {
+      VirtualMemory* storage_;
+      int cells_count_;
+    };
+
+    static int SizeFor(int cell_count) {
+      return sizeof(Header) +
+          Bitmap<BitmapStorageDescriptor>::SizeFor(cell_count);
+    }
+
+    static Header* HeaderOf(Address addr) {
+      return reinterpret_cast<Header*>(addr - sizeof(Header));
+    }
+  };
+
+  typedef Bitmap<BitmapStorageDescriptor> NewSpaceMarkbitsBitmap;
+
+  static NewSpaceMarkbitsBitmap* new_space_bitmap_;
+};
+
 // -------------------------------------------------------------------------
 // Mark-Compact collector
 //
 // All methods are static.
 
 class MarkCompactCollector: public AllStatic {
  public:
   // Type of functions to compute forwarding addresses of objects in
   // compacted spaces.  Given an object and its size, return a (non-failure)
   // Object* that will be the object after forwarding.  There is a separate
@@ skipping 41 matching lines @@
   static bool IsCompacting() {
 #ifdef DEBUG
     // For the purposes of asserts we don't want this to keep returning true
     // after the collection is completed.
     return state_ != IDLE && compacting_collection_;
 #else
     return compacting_collection_;
 #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_; }
 
 #ifdef DEBUG
   // Checks whether performing mark-compact collection.
   static bool in_use() { return state_ > PREPARE_GC; }
   static bool are_map_pointers_encoded() { return state_ == UPDATE_POINTERS; }
 #endif
 
@@ skipping 26 matching lines @@
 
   // Global flag that forces a compaction.
   static bool force_compaction_;
 
   // Global flag indicating whether spaces were compacted on the last GC.
   static bool compacting_collection_;
 
   // 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_;
 
   // Finishes GC, performs heap verification if enabled.
   static void Finish();
 
   // -----------------------------------------------------------------------
   // Phase 1: Marking live objects.
   //
   //  Before: The heap has been prepared for garbage collection by
   //          MarkCompactCollector::Prepare() and is otherwise in its
   //          normal state.
   //
   //   After: Live objects are marked and non-live objects are unmarked.
 
 
   friend class RootMarkingVisitor;
   friend class MarkingVisitor;
   friend class StaticMarkingVisitor;
   friend class CodeMarkingVisitor;
   friend class SharedFunctionInfoMarkingVisitor;
 
   static void PrepareForCodeFlushing();
 
   // Marking operations for objects reachable from roots.
   static void MarkLiveObjects();
 
-  static void MarkUnmarkedObject(HeapObject* obj);
-
   static inline void MarkObject(HeapObject* obj) {
-    if (!obj->IsMarked()) MarkUnmarkedObject(obj);
+    if (!Marking::TestAndMark(obj->address())) {
+      tracer_->increment_marked_count();
+#ifdef DEBUG
+      UpdateLiveObjectCount(obj);
+#endif
+      ProcessNewlyMarkedObject(obj);
+    }
   }
 
   static inline void SetMark(HeapObject* obj) {
+    Marking::SetMark(obj);
     tracer_->increment_marked_count();
 #ifdef DEBUG
     UpdateLiveObjectCount(obj);
 #endif
-    obj->SetMark();
   }
 
+  static void ProcessNewlyMarkedObject(HeapObject* obj);
+
   // Creates back pointers for all map transitions, stores them in
   // the prototype field.  The original prototype pointers are restored
   // in ClearNonLiveTransitions().  All JSObject maps
   // connected by map transitions have the same prototype object, which
   // is why we can use this field temporarily for back pointers.
   static void CreateBackPointers();
 
   // Mark a Map and its DescriptorArray together, skipping transitions.
   static void MarkMapContents(Map* map);
   static void MarkDescriptorArray(DescriptorArray* descriptors);
@@ skipping 68 matching lines @@
   // Iterates the live objects between a range of addresses, returning the
   // number of live objects.
   static int IterateLiveObjectsInRange(Address start, Address end,
                                        HeapObjectCallback size_func);
 
   // 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.
   static void SweepSpaces();
 
+  static void SweepNewSpace(NewSpace* space);
+  static void SweepSpace(PagedSpace* space);
+
 #ifdef DEBUG
   // -----------------------------------------------------------------------
   // Debugging variables, functions and classes
   // Counters used for debugging the marking phase of mark-compact or
   // mark-sweep collection.
 
   // Size of live objects in Heap::to_space_.
   static int live_young_objects_size_;
 
   // Size of live objects in Heap::old_pointer_space_.
@@ skipping 22 matching lines @@
 
   friend class UnmarkObjectVisitor;
   static void UnmarkObject(HeapObject* obj);
 #endif
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_