Implement progress bar for large objects.

src/incremental-marking.cc

Index: src/incremental-marking.cc
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index b34d6d902c8a59761d4578a1722df83410dc4993..e9fd74c0d18dabccea727270af200308af6ff031 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -188,16 +188,78 @@ static void MarkObjectGreyDoNotEnqueue(Object* obj) {
 }
 
 
+static inline void MarkBlackOrKeepGrey(HeapObject* heap_object,
+                                       MarkBit mark_bit,
+                                       int size) {
+  ASSERT(!Marking::IsImpossible(mark_bit));
+  if (mark_bit.Get()) return;
+  mark_bit.Set();
+  MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size);
+  ASSERT(Marking::IsBlack(mark_bit));
+}
+
+
+static inline void MarkBlackOrKeepBlack(HeapObject* heap_object,
+                                        MarkBit mark_bit,
+                                        int size) {
+  ASSERT(!Marking::IsImpossible(mark_bit));
+  if (Marking::IsBlack(mark_bit)) return;
+  Marking::MarkBlack(mark_bit);
+  MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(), size);
+  ASSERT(Marking::IsBlack(mark_bit));
+}
+
+
 class IncrementalMarkingMarkingVisitor
     : public StaticMarkingVisitor<IncrementalMarkingMarkingVisitor> {
  public:
   static void Initialize() {
     StaticMarkingVisitor<IncrementalMarkingMarkingVisitor>::Initialize();
-
+    table_.Register(kVisitFixedArray, &VisitFixedArrayIncremental);
     table_.Register(kVisitNativeContext, &VisitNativeContextIncremental);
     table_.Register(kVisitJSRegExp, &VisitJSRegExp);
   }
 
+  static const int kProgressBarScanningChunk = 32 * 1024;
+
+  static void VisitFixedArrayIncremental(Map* map, HeapObject* object) {
+    MemoryChunk* chunk = MemoryChunk::FromAddress(object->address());
+    // TODO(mstarzinger): Move setting of the flag to the allocation site of
+    // the array. The visitor should just check the flag.
+    if (FLAG_use_marking_progress_bar &&
+        chunk->owner()->identity() == LO_SPACE) {
+      chunk->SetFlag(MemoryChunk::HAS_PROGRESS_BAR);
+    }
+    if (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR)) {
+      Heap* heap = map->GetHeap();
+      // When using a progress bar for large fixed arrays, scan only a chunk of
+      // the array and try to push it onto the marking deque again until it is
+      // fully scanned. Fall back to scanning it through to the end in case this
+      // fails because of a full deque.
+      int object_size = FixedArray::BodyDescriptor::SizeOf(map, object);
+      int start_offset = Max(FixedArray::BodyDescriptor::kStartOffset,
+                             chunk->progress_bar());
+      int end_offset = Min(object_size,
+                           start_offset + kProgressBarScanningChunk);
+      bool scan_until_end = false;
+      do {
+        VisitPointersWithAnchor(heap,
+                                HeapObject::RawField(object, 0),
+                                HeapObject::RawField(object, start_offset),
+                                HeapObject::RawField(object, end_offset));
+        start_offset = end_offset;
+        end_offset = Min(object_size, end_offset + kProgressBarScanningChunk);
+        scan_until_end = heap->incremental_marking()->marking_deque()->IsFull();
+      } while (scan_until_end && start_offset < object_size);
+      chunk->set_progress_bar(start_offset);
+      if (start_offset < object_size) {
+        heap->incremental_marking()->marking_deque()->UnshiftGrey(object);
+      }
+    } else {
+      FixedArrayVisitor::Visit(map, object);
+    }
+  }
+
   static void VisitNativeContextIncremental(Map* map, HeapObject* object) {
     Context* context = Context::cast(object);
 
@@ -234,15 +296,25 @@ class IncrementalMarkingMarkingVisitor
     }
   }
 
+  INLINE(static void VisitPointersWithAnchor(Heap* heap,
+                                             Object** anchor,
+                                             Object** start,
+                                             Object** end)) {
+    for (Object** p = start; p < end; p++) {
+      Object* obj = *p;
+      if (obj->NonFailureIsHeapObject()) {
+        heap->mark_compact_collector()->RecordSlot(anchor, p, obj);
+        MarkObject(heap, obj);
+      }
+    }
+  }
+
   // Marks the object grey and pushes it on the marking stack.
   INLINE(static void MarkObject(Heap* heap, Object* obj)) {
     HeapObject* heap_object = HeapObject::cast(obj);
     MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
     if (mark_bit.data_only()) {
-      if (heap->incremental_marking()->MarkBlackOrKeepGrey(mark_bit)) {
-        MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(),
-                                              heap_object->Size());
-      }
+      MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
     } else if (Marking::IsWhite(mark_bit)) {
       heap->incremental_marking()->WhiteToGreyAndPush(heap_object, mark_bit);
     }
@@ -288,10 +360,7 @@ class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
     HeapObject* heap_object = HeapObject::cast(obj);
     MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
     if (mark_bit.data_only()) {
-      if (incremental_marking_->MarkBlackOrKeepGrey(mark_bit)) {
-          MemoryChunk::IncrementLiveBytesFromGC(heap_object->address(),
-                                                heap_object->Size());
-      }
+      MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
     } else {
       if (Marking::IsWhite(mark_bit)) {
         incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
@@ -616,8 +685,11 @@ void IncrementalMarking::UpdateMarkingDequeAfterScavenge() {
       ASSERT(new_top != marking_deque_.bottom());
 #ifdef DEBUG
         MarkBit mark_bit = Marking::MarkBitFrom(obj);
+        MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
         ASSERT(Marking::IsGrey(mark_bit) ||
-               (obj->IsFiller() && Marking::IsWhite(mark_bit)));
+               (obj->IsFiller() && Marking::IsWhite(mark_bit)) ||
+               (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) &&
+                Marking::IsBlack(mark_bit)));
 #endif
     }
   }
@@ -637,11 +709,15 @@ void IncrementalMarking::VisitObject(Map* map, HeapObject* obj, int size) {
 
   IncrementalMarkingMarkingVisitor::IterateBody(map, obj);
 
-  MarkBit obj_mark_bit = Marking::MarkBitFrom(obj);
-  SLOW_ASSERT(Marking::IsGrey(obj_mark_bit) ||
-             (obj->IsFiller() && Marking::IsWhite(obj_mark_bit)));
-  Marking::MarkBlack(obj_mark_bit);
-  MemoryChunk::IncrementLiveBytesFromGC(obj->address(), size);
+  MarkBit mark_bit = Marking::MarkBitFrom(obj);
+#ifdef DEBUG
+  MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
+  SLOW_ASSERT(Marking::IsGrey(mark_bit) ||
+              (obj->IsFiller() && Marking::IsWhite(mark_bit)) ||
+              (chunk->IsFlagSet(MemoryChunk::HAS_PROGRESS_BAR) &&
+               Marking::IsBlack(mark_bit)));
+#endif
+  MarkBlackOrKeepBlack(obj, mark_bit, size);
 }