Updates incremental marking pass to collect object statistics.

src/heap/incremental-marking.cc

 // 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.
 
 #include "src/heap/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/heap/gc-idle-time-handler.h"
 #include "src/heap/gc-tracer.h"
 #include "src/heap/mark-compact-inl.h"
+#include "src/heap/object-stats.h"
+#include "src/heap/objects-visiting-inl.h"
 #include "src/heap/objects-visiting.h"
-#include "src/heap/objects-visiting-inl.h"
 #include "src/tracing/trace-event.h"
 #include "src/v8.h"
 
 namespace v8 {
 namespace internal {
 
 IncrementalMarking::StepActions IncrementalMarking::IdleStepActions() {
   return StepActions(IncrementalMarking::NO_GC_VIA_STACK_GUARD,
                      IncrementalMarking::FORCE_MARKING,
                      IncrementalMarking::DO_NOT_FORCE_COMPLETION);
@@ skipping 143 matching lines @@
 
 
 class IncrementalMarkingMarkingVisitor
     : public StaticMarkingVisitor<IncrementalMarkingMarkingVisitor> {
  public:
   static void Initialize() {
     StaticMarkingVisitor<IncrementalMarkingMarkingVisitor>::Initialize();
     table_.Register(kVisitFixedArray, &VisitFixedArrayIncremental);
     table_.Register(kVisitNativeContext, &VisitNativeContextIncremental);
     table_.Register(kVisitJSRegExp, &VisitJSRegExp);
+    if (FLAG_trace_gc_object_stats) {
+      ObjectStatsVisitor::Initialize(&table_);
+    }

[mythria, 2016/05/03 16:04:34]

Hannes, I initialize the Visitor table only with IncrementalMarking visitor.
This means that objects visited during MarkCompact phase are not accounted for
in the object statistics. I think correct fix is to account for objects visited
during both these phases. Just wanted to check with you if my understanding is
correct before I implement it. 

If I understand correctly, if an object is marked during IncrementalMarking
phase it will not be marked again during MarkCompact phase. Otherwise, we may
count objects twice. 

[Hannes Payer (out of office), 2016/05/09 13:16:37]

That is correct. In case incremental marking is aborted you have to reset the
counters.

   }
 
   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) {
@@ skipping 1052 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8