[heap] Reland "Remove black pages and use black areas instead."

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 200 matching lines @@
   }
 
   inline Address CurrentCellBase() {
     DCHECK(cell_index_ == Bitmap::IndexToCell(Bitmap::CellAlignIndex(
                               chunk_->AddressToMarkbitIndex(cell_base_))));
     return cell_base_;
   }
 
   inline void Advance() {
     cell_index_++;
-    cell_base_ += 32 * kPointerSize;
+    cell_base_ += Bitmap::kBitsPerCell * kPointerSize;
+  }
+
+  inline bool Advance(unsigned int new_cell_index) {
+    if (new_cell_index != cell_index_) {
+      DCHECK_GT(new_cell_index, cell_index_);
+      DCHECK_LE(new_cell_index, last_cell_index_);
+      unsigned int diff = new_cell_index - cell_index_;
+      cell_index_ = new_cell_index;
+      cell_base_ += diff * (Bitmap::kBitsPerCell * kPointerSize);
+      return true;
+    }
+    return false;
   }
 
   // Return the next mark bit cell. If there is no next it returns 0;
   inline MarkBit::CellType PeekNext() {
     if (HasNext()) {
       return cells_[cell_index_ + 1];
     }
     return 0;
   }
 
@@ skipping 14 matching lines @@
 };
 
 template <LiveObjectIterationMode T>
 class LiveObjectIterator BASE_EMBEDDED {
  public:
   explicit LiveObjectIterator(MemoryChunk* chunk)
       : chunk_(chunk),
         it_(chunk_),
         cell_base_(it_.CurrentCellBase()),
         current_cell_(*it_.CurrentCell()) {
-    // Black pages can not be iterated.
-    DCHECK(!chunk->IsFlagSet(Page::BLACK_PAGE));
   }
 
   HeapObject* Next();
 
  private:
   MemoryChunk* chunk_;
   MarkBitCellIterator it_;
   Address cell_base_;
   MarkBit::CellType current_cell_;
 };
@@ skipping 493 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_