[heap] Provide ObjectMarking with marking transitions

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 28 matching lines @@
   V8_INLINE static MarkBit MarkBitFrom(HeapObject* obj) {
     const Address address = obj->address();
     MemoryChunk* p = MemoryChunk::FromAddress(address);
     return p->markbits()->MarkBitFromIndex(p->AddressToMarkbitIndex(address));
   }
 
   static Marking::ObjectColor Color(HeapObject* obj) {
     return Marking::Color(ObjectMarking::MarkBitFrom(obj));
   }
 
+  V8_INLINE static void MarkWhite(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    if (Marking::IsBlack(markbit)) {
+      MemoryChunk::IncrementLiveBytes(obj, -obj->Size());
+    }
+    Marking::MarkWhite(markbit);
+  }
+

[Hannes Payer (out of office), 2017/01/18 14:43:35]

Should we add DCHECKs to the transitions where we expect a color? The lower
level has the DCHECKs but this may change for whatever reason.

[Michael Lippautz, 2017/01/18 15:58:07]

Done.

+  V8_INLINE static void BlackToWhite(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    Marking::BlackToWhite(markbit);
+    MemoryChunk::IncrementLiveBytes(obj, -obj->Size());
+  }
+
+  V8_INLINE static void GreyToWhite(HeapObject* obj) {
+    Marking::GreyToWhite(MarkBitFrom(obj));
+  }
+
+  V8_INLINE static void BlackToGrey(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    Marking::BlackToGrey(markbit);
+    MemoryChunk::IncrementLiveBytes(obj, -obj->Size());
+  }
+
+  V8_INLINE static void WhiteToGrey(HeapObject* obj) {
+    Marking::WhiteToGrey(MarkBitFrom(obj));
+  }
+
+  V8_INLINE static void WhiteToBlack(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    Marking::WhiteToBlack(markbit);
+    MemoryChunk::IncrementLiveBytes(obj, obj->Size());
+  }
+
+  V8_INLINE static void GreyToBlack(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    Marking::GreyToBlack(markbit);
+    MemoryChunk::IncrementLiveBytes(obj, obj->Size());
+  }
+
+  V8_INLINE static void AnyToGrey(HeapObject* obj) {
+    MarkBit markbit = MarkBitFrom(obj);
+    if (Marking::IsBlack(markbit)) {
+      MemoryChunk::IncrementLiveBytes(obj, -obj->Size());
+    }
+    Marking::AnyToGrey(markbit);
+  }
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ObjectMarking);
 };
 
 // ----------------------------------------------------------------------------
 // Marking deque for tracing live objects.
 class MarkingDeque {
  public:
   explicit MarkingDeque(Heap* heap)
       : backing_store_(nullptr),
@@ skipping 719 matching lines @@
 
  private:
   MarkCompactCollector* collector_;
 };
 
 V8_EXPORT_PRIVATE const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_