[heap] Black allocation.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 32513b7c960b4d78f606eeade15fa0987a5943ed..1f72a130cda88cf2f2ca7499201985c5b2b8d900 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -201,6 +201,8 @@ class Bitmap {
 
   static inline void Clear(MemoryChunk* chunk);
 
+  static inline void SetAllBits(MemoryChunk* chunk);
+
   static void PrintWord(uint32_t word, uint32_t himask = 0) {
     for (uint32_t mask = 1; mask != 0; mask <<= 1) {
       if ((mask & himask) != 0) PrintF("[");
@@ -309,6 +311,11 @@ class MemoryChunk {
     // to grey transition is performed in the value.
     HAS_PROGRESS_BAR,
 
+    // A black page has all mark bits set to 1 (black). A black page currently
+    // cannot be iterated because it is not swept. Moreover live bytes are also
+    // not updated.
+    BLACK_PAGE,
+
     // This flag is intended to be used for testing. Works only when both
     // FLAG_stress_compaction and FLAG_manual_evacuation_candidates_selection
     // are set. It forces the page to become an evacuation candidate at next
@@ -461,11 +468,13 @@ class MemoryChunk {
   inline void IncrementLiveBytes(int by);
 
   int LiveBytes() {
-    DCHECK_LE(static_cast<size_t>(live_byte_count_), size_);
+    DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
+    DCHECK(!IsFlagSet(BLACK_PAGE) || live_byte_count_ == 0);
     return live_byte_count_;
   }
 
   void SetLiveBytes(int live_bytes) {
+    if (IsFlagSet(BLACK_PAGE)) return;
     DCHECK_GE(live_bytes, 0);
     DCHECK_LE(static_cast<size_t>(live_bytes), size_);
     live_byte_count_ = live_bytes;
@@ -2142,6 +2151,7 @@ class PagedSpace : public Space {
   // Mutex guarding any concurrent access to the space.
   base::Mutex space_mutex_;
 
+  friend class IncrementalMarking;
   friend class MarkCompactCollector;
   friend class PageIterator;