[heap] Simplify MarkingDeque implementation.

src/heap/mark-compact-inl.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_INL_H_
 #define V8_HEAP_MARK_COMPACT_INL_H_
 
 #include "src/heap/mark-compact.h"
 #include "src/isolate.h"
 
 
 namespace v8 {
 namespace internal {
 
 
 void MarkCompactCollector::SetFlags(int flags) {
   reduce_memory_footprint_ = ((flags & Heap::kReduceMemoryFootprintMask) != 0);
   abort_incremental_marking_ =
       ((flags & Heap::kAbortIncrementalMarkingMask) != 0);
   finalize_incremental_marking_ =
       ((flags & Heap::kFinalizeIncrementalMarkingMask) != 0);
   DCHECK(!finalize_incremental_marking_ || !abort_incremental_marking_);
 }
 
 
+void MarkCompactCollector::PushBlack(HeapObject* obj) {
+  if (marking_deque_.PushBlack(obj)) {
+    MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
+  } else {
+    Marking::BlackToGrey(obj);
+  }
+}
+
+
+void MarkCompactCollector::UnshiftBlack(HeapObject* obj) {
+  if (!marking_deque_.UnshiftBlack(obj)) {
+    MemoryChunk::IncrementLiveBytesFromGC(obj, -obj->Size());
+    Marking::BlackToGrey(obj);
+  }
+}
+
+
 void MarkCompactCollector::MarkObject(HeapObject* obj, MarkBit mark_bit) {
   DCHECK(Marking::MarkBitFrom(obj) == mark_bit);
   if (Marking::IsWhite(mark_bit)) {
     Marking::WhiteToBlack(mark_bit);
-    MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
     DCHECK(obj->GetIsolate()->heap()->Contains(obj));
-    marking_deque_.PushBlack(obj);
+    PushBlack(obj);
   }
 }
 
 
 void MarkCompactCollector::SetMark(HeapObject* obj, MarkBit mark_bit) {
   DCHECK(Marking::IsWhite(mark_bit));
   DCHECK(Marking::MarkBitFrom(obj) == mark_bit);
   Marking::WhiteToBlack(mark_bit);
   MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
 }
@@ skipping 103 matching lines @@
 
 void CodeFlusher::ClearNextCodeMap(SharedFunctionInfo* holder) {
   FixedArray* code_map = FixedArray::cast(holder->optimized_code_map());
   code_map->set_undefined(SharedFunctionInfo::kNextMapIndex);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_INL_H_