[heap] Prepare IncrementalMarking::VisitObject for concurrent marking.

Currently the VisitObject function iterates the object and then colors
it black. This does not work well with concurrent marking. The function
should instead first try to mark the object black and iterate its body
only if the color transition succeeds.

BUG=chromium:694255

Review-Url: https://codereview.chromium.org/2853323003
Cr-Commit-Position: refs/heads/master@{#45095}

src/heap/incremental-marking.cc

@@ -835,12 +835,13 @@ void IncrementalMarking::UpdateMarkingDequeAfterScavenge() {
   });
 }
 
+bool IncrementalMarking::IsFixedArrayWithProgressBar(HeapObject* obj) {
+  if (!obj->IsFixedArray()) return false;
+  MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
+  return chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR);
+}
 
 void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) {
-  WhiteToGreyAndPush(map);
-
-  IncrementalMarkingMarkingVisitor::IterateBody(map, obj);
-
 #if ENABLE_SLOW_DCHECKS
   MarkBit mark_bit = ObjectMarking::MarkBitFrom(obj, marking_state(obj));
   MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
@@ -848,7 +849,13 @@ void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) {
               (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) &&
                Marking::IsBlack<kAtomicity>(mark_bit)));
 #endif
-  ObjectMarking::GreyToBlack<kAtomicity>(obj, marking_state(obj));
+  if (ObjectMarking::GreyToBlack<kAtomicity>(obj, marking_state(obj))) {
+    WhiteToGreyAndPush(map);
+    IncrementalMarkingMarkingVisitor::IterateBody(map, obj);
+  } else if (IsFixedArrayWithProgressBar(obj)) {
+    DCHECK(ObjectMarking::IsBlack<kAtomicity>(obj, marking_state(obj)));
+    IncrementalMarkingMarkingVisitor::VisitFixedArrayIncremental(map, obj);
+  }
 }
 
 intptr_t IncrementalMarking::ProcessMarkingDeque(

src/heap/incremental-marking.h

@@ -312,6 +312,7 @@ class V8_EXPORT_PRIVATE IncrementalMarking {
       intptr_t bytes_to_process,
       ForceCompletionAction completion = DO_NOT_FORCE_COMPLETION));
 
+  INLINE(bool IsFixedArrayWithProgressBar(HeapObject* object));
   INLINE(void VisitObject(Map* map, HeapObject* obj, int size));
 
   void IncrementIdleMarkingDelayCounter();