Heap profiler should report implicit references.

Implicit references reported to V8 with V8::AddImplicitReferences calls are now reported by heap profiler as 'native' references with type kInternal.

Original WebKit bug report: https://bugs.webkit.org/show_bug.cgi?id=77414
Review URL: https://chromiumcodereview.appspot.com/9316092

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10603 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/profile-generator.cc

@@ -2783,6 +2783,27 @@ void NativeObjectsExplorer::FillRetainedObjects() {
   embedder_queried_ = true;
 }
 
+void NativeObjectsExplorer::FillImplicitReferences() {
+  Isolate* isolate = Isolate::Current();
+  List<ImplicitRefGroup*>* groups =
+      isolate->global_handles()->implicit_ref_groups();
+  for (int i = 0; i < groups->length(); ++i) {
+    ImplicitRefGroup* group = groups->at(i);
+    HeapObject* parent = *group->parent_;
+    HeapEntry* parent_entry = filler_->FindOrAddEntry(parent, this);
+    ASSERT(parent_entry != NULL);
+    Object*** children = group->children_;
+    for (size_t j = 0; j < group->length_; ++j) {
+      Object* child = *children[j];
+      HeapEntry* child_entry = filler_->FindOrAddEntry(child, this);
+      filler_->SetNamedReference(
+          HeapGraphEdge::kInternal,
+          parent, parent_entry,
+          "native",
+          child, child_entry);
+    }
+  }
+}
 
 List<HeapObject*>* NativeObjectsExplorer::GetListMaybeDisposeInfo(
     v8::RetainedObjectInfo* info) {
@@ -2799,22 +2820,24 @@ List<HeapObject*>* NativeObjectsExplorer::GetListMaybeDisposeInfo(
 
 bool NativeObjectsExplorer::IterateAndExtractReferences(
     SnapshotFillerInterface* filler) {
-  if (EstimateObjectsCount() <= 0) return true;
   filler_ = filler;
   FillRetainedObjects();
-  for (HashMap::Entry* p = objects_by_info_.Start();
-       p != NULL;
-       p = objects_by_info_.Next(p)) {
-    v8::RetainedObjectInfo* info =
-        reinterpret_cast<v8::RetainedObjectInfo*>(p->key);
-    SetNativeRootReference(info);
-    List<HeapObject*>* objects =
-        reinterpret_cast<List<HeapObject*>* >(p->value);
-    for (int i = 0; i < objects->length(); ++i) {
-      SetWrapperNativeReferences(objects->at(i), info);
+  FillImplicitReferences();
+  if (EstimateObjectsCount() > 0) {
+    for (HashMap::Entry* p = objects_by_info_.Start();
+         p != NULL;
+         p = objects_by_info_.Next(p)) {
+      v8::RetainedObjectInfo* info =
+          reinterpret_cast<v8::RetainedObjectInfo*>(p->key);
+      SetNativeRootReference(info);
+      List<HeapObject*>* objects =
+          reinterpret_cast<List<HeapObject*>* >(p->value);
+      for (int i = 0; i < objects->length(); ++i) {
+        SetWrapperNativeReferences(objects->at(i), info);
+      }
     }
+    SetRootNativeRootsReference();
   }
-  SetRootNativeRootsReference();
   filler_ = NULL;
   return true;
 }

src/profile-generator.h

@@ -1042,6 +1042,7 @@ class NativeObjectsExplorer : public HeapEntriesAllocator {
 
  private:
   void FillRetainedObjects();
+  void FillImplicitReferences();
   List<HeapObject*>* GetListMaybeDisposeInfo(v8::RetainedObjectInfo* info);
   void SetNativeRootReference(v8::RetainedObjectInfo* info);
   void SetRootNativeRootsReference();

test/cctest/test-heap-profiler.cc

@@ -805,6 +805,75 @@ TEST(HeapSnapshotRetainedObjectInfo) {
 }
 
 
+class GraphWithImplicitRefs {
+ public:
+  static const int kObjectsCount = 4;
+  explicit GraphWithImplicitRefs(LocalContext* env) {
+    CHECK_EQ(NULL, instance_);
+    instance_ = this;
+    for (int i = 0; i < kObjectsCount; i++) {
+      objects_[i] = v8::Persistent<v8::Object>::New(v8::Object::New());
+    }
+    (*env)->Global()->Set(v8_str("root_object"), objects_[0]);
+  }
+  ~GraphWithImplicitRefs() {
+    instance_ = NULL;
+  }
+
+  static void gcPrologue() {
+    instance_->AddImplicitReferences();
+  }
+
+ private:
+  void AddImplicitReferences() {
+    // 0 -> 1
+    v8::V8::AddImplicitReferences(
+        v8::Persistent<v8::Object>::Cast(objects_[0]), &objects_[1], 1);
+    // Adding two more references(note length=2 in params): 1 -> 2, 1 -> 3
+    v8::V8::AddImplicitReferences(
+        v8::Persistent<v8::Object>::Cast(objects_[1]), &objects_[2], 2);
+  }
+
+  v8::Persistent<v8::Value> objects_[kObjectsCount];
+  static GraphWithImplicitRefs* instance_;
+};
+
+GraphWithImplicitRefs* GraphWithImplicitRefs::instance_ = NULL;
+
+
+TEST(HeapSnapshotImplicitReferences) {
+  v8::HandleScope scope;
+  LocalContext env;
+
+  GraphWithImplicitRefs graph(&env);
+  v8::V8::SetGlobalGCPrologueCallback(&GraphWithImplicitRefs::gcPrologue);
+
+  const v8::HeapSnapshot* snapshot =
+      v8::HeapProfiler::TakeSnapshot(v8_str("implicit_refs"));
+
+  const v8::HeapGraphNode* global_object = GetGlobalObject(snapshot);
+  // Use kShortcut type to skip intermediate JSGlobalPropertyCell
+  const v8::HeapGraphNode* obj0 = GetProperty(
+      global_object, v8::HeapGraphEdge::kShortcut, "root_object");
+  CHECK(obj0);
+  CHECK_EQ(v8::HeapGraphNode::kObject, obj0->GetType());
+  const v8::HeapGraphNode* obj1 = GetProperty(
+      obj0, v8::HeapGraphEdge::kInternal, "native");
+  CHECK(obj1);
+  int implicit_targets_count = 0;
+  for (int i = 0, count = obj1->GetChildrenCount(); i < count; ++i) {
+    const v8::HeapGraphEdge* prop = obj1->GetChild(i);
+    v8::String::AsciiValue prop_name(prop->GetName());
+    if (prop->GetType() == v8::HeapGraphEdge::kInternal &&
+        strcmp("native", *prop_name) == 0) {
+      ++implicit_targets_count;
+    }
+  }
+  CHECK_EQ(2, implicit_targets_count);
+  v8::V8::SetGlobalGCPrologueCallback(NULL);
+}
+
+
 TEST(DeleteAllHeapSnapshots) {
   v8::HandleScope scope;
   LocalContext env;