Fix counting of scanned bytes in incremental marking step for large object.

src/incremental-marking.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 36 matching lines @@
       steps_count_(0),
       steps_took_(0),
       longest_step_(0.0),
       old_generation_space_available_at_start_of_incremental_(0),
       old_generation_space_used_at_start_of_incremental_(0),
       steps_count_since_last_gc_(0),
       steps_took_since_last_gc_(0),
       should_hurry_(false),
       marking_speed_(0),
       allocated_(0),
-      no_marking_scope_depth_(0) {
+      no_marking_scope_depth_(0),
+      unscanned_bytes_of_large_object_(0) {
 }
 
 
 void IncrementalMarking::TearDown() {
   delete marking_deque_memory_;
 }
 
 
 void IncrementalMarking::RecordWriteSlow(HeapObject* obj,
                                          Object** slot,
@@ skipping 166 matching lines @@
       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);
+      int already_scanned_offset = start_offset;
       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);
+        heap->incremental_marking()->NotifyIncompleteScanOfObject(
+            object_size - (start_offset - already_scanned_offset));
       }
     } else {
       FixedArrayVisitor::Visit(map, object);
     }
   }
 
   static void VisitNativeContextIncremental(Map* map, HeapObject* object) {
     Context* context = Context::cast(object);
 
     // We will mark cache black with a separate pass
@@ skipping 465 matching lines @@
   Map* filler_map = heap_->one_pointer_filler_map();
   while (!marking_deque_.IsEmpty() && bytes_to_process > 0) {
     HeapObject* obj = marking_deque_.Pop();
 
     // Explicitly skip one word fillers. Incremental markbit patterns are
     // correct only for objects that occupy at least two words.
     Map* map = obj->map();
     if (map == filler_map) continue;
 
     int size = obj->SizeFromMap(map);
-    bytes_to_process -= size;
+    unscanned_bytes_of_large_object_ = 0;
     VisitObject(map, obj, size);
+    bytes_to_process -= (size - unscanned_bytes_of_large_object_);
   }
 }
 
 
 void IncrementalMarking::ProcessMarkingDeque() {
   Map* filler_map = heap_->one_pointer_filler_map();
   while (!marking_deque_.IsEmpty()) {
     HeapObject* obj = marking_deque_.Pop();
 
     // Explicitly skip one word fillers. Incremental markbit patterns are
@@ skipping 269 matching lines @@
   bytes_scanned_ = 0;
   write_barriers_invoked_since_last_step_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
 
 } }  // namespace v8::internal