[heap] Unify MarkingDeque push and unshift operations.

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 "src/base/bits.h"
 #include "src/heap/spaces.h"
 
@@ skipping 187 matching lines @@
   inline bool IsEmpty() { return top_ == bottom_; }
 
   bool overflowed() const { return overflowed_; }
 
   bool in_use() const { return in_use_; }
 
   void ClearOverflowed() { overflowed_ = false; }
 
   void SetOverflowed() { overflowed_ = true; }
 
-  // Push the (marked) object on the marking stack if there is room, otherwise
-  // mark the deque as overflowed and wait for a rescan of the heap.
-  INLINE(bool PushBlack(HeapObject* object)) {
+  // Push the object on the marking stack if there is room, otherwise mark the
+  // deque as overflowed and wait for a rescan of the heap.
+  INLINE(bool Push(HeapObject* object)) {
     DCHECK(object->IsHeapObject());
     if (IsFull()) {
       SetOverflowed();
       return false;
     } else {
       array_[top_] = object;
       top_ = ((top_ + 1) & mask_);
       return true;
     }
   }
 
-  INLINE(void PushGrey(HeapObject* object)) {
-    DCHECK(object->IsHeapObject());
-    if (IsFull()) {
-      SetOverflowed();
-    } else {
-      array_[top_] = object;
-      top_ = ((top_ + 1) & mask_);
-    }
-  }
-
   INLINE(HeapObject* Pop()) {
     DCHECK(!IsEmpty());
     top_ = ((top_ - 1) & mask_);
     HeapObject* object = array_[top_];
     DCHECK(object->IsHeapObject());
     return object;
   }
 
-  INLINE(void UnshiftGrey(HeapObject* object)) {
+  // Unshift the object into the marking stack if there is room, otherwise mark
+  // the deque as overflowed and wait for a rescan of the heap.
+  INLINE(bool Unshift(HeapObject* object)) {
     DCHECK(object->IsHeapObject());
     if (IsFull()) {
       SetOverflowed();
-    } else {
-      bottom_ = ((bottom_ - 1) & mask_);
-      array_[bottom_] = object;
-    }
-  }
-
-  INLINE(bool UnshiftBlack(HeapObject* object)) {
-    DCHECK(object->IsHeapObject());
-    DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
-    if (IsFull()) {
-      SetOverflowed();
       return false;
     } else {
       bottom_ = ((bottom_ - 1) & mask_);
       array_[bottom_] = object;
       return true;
     }
   }
 
   HeapObject** array() { return array_; }
   int bottom() { return bottom_; }
@@ skipping 732 matching lines @@
  private:
   MarkCompactCollector* collector_;
 };
 
 
 const char* AllocationSpaceName(AllocationSpace space);
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_MARK_COMPACT_H_