[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 e233b328511601a46e9a6815763997175cdd9aa1..9289f9d060d3a083520042bac52a3237df3b388e 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -203,6 +203,8 @@ 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("[");
@@ -314,6 +316,11 @@ 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
@@ -573,6 +580,7 @@ class MemoryChunk {
   }
 
   void IncrementLiveBytes(int by) {
+    if (IsFlagSet(BLACK_PAGE)) return;
     if (FLAG_gc_verbose) {
       printf("UpdateLiveBytes:%p:%x%c=%x->%x\n", static_cast<void*>(this),
              live_byte_count_, ((by < 0) ? '-' : '+'), ((by < 0) ? -by : by),
@@ -585,10 +593,12 @@ class MemoryChunk {
 
   int LiveBytes() {
     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<unsigned>(live_bytes), size_);
     live_byte_count_ = live_bytes;
@@ -2181,6 +2191,7 @@ 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;