[heap] Allow concurrently transferring colors

src/heap/spaces.h

 // Copyright 2011 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_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include <list>
 #include <memory>
 #include <unordered_set>
@@ skipping 652 matching lines @@
 
   static MarkingState Internal(MemoryChunk* chunk) {
     return MarkingState(
         Bitmap::FromAddress(chunk->address() + MemoryChunk::kHeaderSize),
         &chunk->live_byte_count_);
   }
 
   MarkingState(Bitmap* bitmap, intptr_t* live_bytes)
       : bitmap_(bitmap), live_bytes_(live_bytes) {}
 
-  void IncrementLiveBytes(intptr_t by) const {
-    *live_bytes_ += static_cast<int>(by);
-  }
+  template <MarkBit::AccessMode mode = MarkBit::NON_ATOMIC>
+  inline void IncrementLiveBytes(intptr_t by) const;
+
   void SetLiveBytes(intptr_t value) const {
     *live_bytes_ = static_cast<int>(value);
   }
 
   void ClearLiveness() const {
     bitmap_->Clear();
     *live_bytes_ = 0;
   }
 
   Bitmap* bitmap() const { return bitmap_; }
   intptr_t live_bytes() const { return *live_bytes_; }
 
  private:
   Bitmap* bitmap_;
   intptr_t* live_bytes_;
 };
 
+template <>
+inline void MarkingState::IncrementLiveBytes<MarkBit::NON_ATOMIC>(
+    intptr_t by) const {
+  *live_bytes_ += by;
+}
+
+template <>
+inline void MarkingState::IncrementLiveBytes<MarkBit::ATOMIC>(
+    intptr_t by) const {
+  reinterpret_cast<base::AtomicNumber<intptr_t>*>(live_bytes_)->Increment(by);
+}
+
 // -----------------------------------------------------------------------------
 // A page is a memory chunk of a size 1MB. Large object pages may be larger.
 //
 // The only way to get a page pointer is by calling factory methods:
 //   Page* p = Page::FromAddress(addr); or
 //   Page* p = Page::FromTopOrLimit(top);
 class Page : public MemoryChunk {
  public:
   static const intptr_t kCopyAllFlags = ~0;
 
@@ skipping 2248 matching lines @@
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
   LargePageIterator lo_iterator_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_