[heap] Provide ObjectMarking with marking transitions

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index c931f520b7aea13f03a45941eca58e76d05b65cb..9230bb2d7e1c8158c9e4a20959c2f40edb6051a7 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -398,7 +398,7 @@ void MarkCompactCollector::ClearMarkbits() {
 
   LargeObjectIterator it(heap_->lo_space());
   for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
-    Marking::MarkWhite(ObjectMarking::MarkBitFrom(obj));
+    ObjectMarking::MarkWhite(obj);
     MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
     chunk->ResetProgressBar();
     chunk->ResetLiveBytes();
@@ -1506,7 +1506,7 @@ void MarkCompactCollector::DiscoverGreyObjectsWithIterator(T* it) {
   for (HeapObject* object = it->Next(); object != NULL; object = it->Next()) {
     MarkBit markbit = ObjectMarking::MarkBitFrom(object);
     if ((object->map() != filler_map) && Marking::IsGrey(markbit)) {

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

It is a bit weird now that we still use MarkBit for getters. In this case, why
not have ObjectMarking::IsGrey(object)?

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

Done.

-      Marking::GreyToBlack(markbit);
+      ObjectMarking::GreyToBlack(object);
       PushBlack(object);
       if (marking_deque()->IsFull()) return;
     }
@@ -1520,7 +1520,7 @@ void MarkCompactCollector::DiscoverGreyObjectsOnPage(MemoryChunk* p) {
   while ((object = it.Next()) != NULL) {
     MarkBit markbit = ObjectMarking::MarkBitFrom(object);

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

Same here.

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

Done.

     DCHECK(Marking::IsGrey(markbit));
-    Marking::GreyToBlack(markbit);
+    ObjectMarking::GreyToBlack(object);
     PushBlack(object);
     if (marking_deque()->IsFull()) return;
   }