External references should not affect dominance relation.

Separate objects into two groups: reachable from a window (user),
and unreachable (system). Then do not take into account links
that come from system group to the user group when calculating
dominance relation.

Review URL: https://chromiumcodereview.appspot.com/10086006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11335 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

@@ -5998,7 +5998,7 @@ Handle<Value> HeapGraphEdge::GetName() const {
 const HeapGraphNode* HeapGraphEdge::GetFromNode() const {
   i::Isolate* isolate = i::Isolate::Current();
   IsDeadCheck(isolate, "v8::HeapGraphEdge::GetFromNode");
-  const i::HeapEntry* from = ToInternal(this)->From();
+  const i::HeapEntry* from = ToInternal(this)->from();
   return reinterpret_cast<const HeapGraphNode*>(from);
 }
 

src/profile-generator-inl.h

@@ -95,6 +95,12 @@ CodeEntry* ProfileGenerator::EntryForVMState(StateTag tag) {
 }
 
 
+HeapEntry* HeapGraphEdge::from() const {
+  return const_cast<HeapEntry*>(
+      reinterpret_cast<const HeapEntry*>(this - child_index_) - 1);
+}
+
+
 SnapshotObjectId HeapObjectsMap::GetNthGcSubrootId(int delta) {
   return kGcRootsFirstSubrootId + delta * kObjectIdStep;
 }

src/profile-generator.cc

@@ -957,11 +957,6 @@ void HeapGraphEdge::Init(int child_index, int index, HeapEntry* to) {
 }
 
 
-HeapEntry* HeapGraphEdge::From() {
-  return reinterpret_cast<HeapEntry*>(this - child_index_) - 1;
-}
-
-
 void HeapEntry::Init(HeapSnapshot* snapshot,
                      Type type,
                      const char* name,
@@ -972,6 +967,7 @@ void HeapEntry::Init(HeapSnapshot* snapshot,
   snapshot_ = snapshot;
   type_ = type;
   painted_ = false;
+  reachable_from_window_ = false;
   name_ = name;
   self_size_ = self_size;
   retained_size_ = 0;
@@ -1991,7 +1987,7 @@ void V8HeapExplorer::ExtractReferences(HeapObject* obj) {
     // We use JSGlobalProxy because this is what embedder (e.g. browser)
     // uses for the global object.
     JSGlobalProxy* proxy = JSGlobalProxy::cast(obj);
-    SetRootShortcutReference(proxy->map()->prototype());
+    SetWindowReference(proxy->map()->prototype());
   } else if (obj->IsJSObject()) {
     JSObject* js_obj = JSObject::cast(obj);
     ExtractClosureReferences(js_obj, entry);
@@ -2259,15 +2255,15 @@ void V8HeapExplorer::ExtractPropertyReferences(JSObject* js_obj,
       Object* k = dictionary->KeyAt(i);
       if (dictionary->IsKey(k)) {
         Object* target = dictionary->ValueAt(i);
-        SetPropertyReference(
-            js_obj, entry, String::cast(k), target);
         // We assume that global objects can only have slow properties.
-        if (target->IsJSGlobalPropertyCell()) {
-          SetPropertyShortcutReference(js_obj,
-                                       entry,
-                                       String::cast(k),
-                                       JSGlobalPropertyCell::cast(
-                                           target)->value());
+        Object* value = target->IsJSGlobalPropertyCell()
+            ? JSGlobalPropertyCell::cast(target)->value()
+            : target;
+        if (String::cast(k)->length() > 0) {
+          SetPropertyReference(js_obj, entry, String::cast(k), value);
+        } else {
+          TagObject(value, "(hidden properties)");
+          SetInternalReference(js_obj, entry, "hidden_properties", value);
         }
       }
     }
@@ -2636,7 +2632,7 @@ void V8HeapExplorer::SetRootGcRootsReference() {
 }
 
 
-void V8HeapExplorer::SetRootShortcutReference(Object* child_obj) {
+void V8HeapExplorer::SetWindowReference(Object* child_obj) {
   HeapEntry* child_entry = GetEntry(child_obj);
   ASSERT(child_entry != NULL);
   filler_->SetNamedAutoIndexReference(
@@ -3272,19 +3268,61 @@ bool HeapSnapshotGenerator::FillReferences() {
 }
 
 
-void HeapSnapshotGenerator::FillReversePostorderIndexes(
+bool HeapSnapshotGenerator::IsWindowReference(const HeapGraphEdge& edge) {
+  ASSERT(edge.from() == snapshot_->root());
+  return edge.type() == HeapGraphEdge::kShortcut;
+}
+
+
+void HeapSnapshotGenerator::MarkWindowReachableObjects() {
+  List<HeapEntry*> worklist;
+
+  Vector<HeapGraphEdge> children = snapshot_->root()->children();
+  for (int i = 0; i < children.length(); ++i) {
+    if (IsWindowReference(children[i])) {
+      worklist.Add(children[i].to());
+    }
+  }
+
+  while (!worklist.is_empty()) {
+    HeapEntry* entry = worklist.RemoveLast();
+    if (entry->reachable_from_window()) continue;
+    entry->set_reachable_from_window();
+    Vector<HeapGraphEdge> children = entry->children();
+    for (int i = 0; i < children.length(); ++i) {
+      HeapEntry* child = children[i].to();
+      if (!child->reachable_from_window()) {
+        worklist.Add(child);
+      }
+    }
+  }
+}
+
+
+static bool IsRetainingEdge(HeapGraphEdge* edge) {
+  if (edge->type() == HeapGraphEdge::kShortcut) return false;
+  // The edge is not retaining if it goes from system domain
+  // (i.e. an object not reachable from window) to the user domain
+  // (i.e. a reachable object).
+  return edge->from()->reachable_from_window()
+      || !edge->to()->reachable_from_window();
+}
+
+
+void HeapSnapshotGenerator::FillPostorderIndexes(
     Vector<HeapEntry*>* entries) {
   snapshot_->ClearPaint();
   int current_entry = 0;
   List<HeapEntry*> nodes_to_visit;
-  nodes_to_visit.Add(snapshot_->root());
+  HeapEntry* root = snapshot_->root();
+  nodes_to_visit.Add(root);
   snapshot_->root()->paint();
   while (!nodes_to_visit.is_empty()) {
     HeapEntry* entry = nodes_to_visit.last();
     Vector<HeapGraphEdge> children = entry->children();
     bool has_new_edges = false;
     for (int i = 0; i < children.length(); ++i) {
-      if (children[i].type() == HeapGraphEdge::kShortcut) continue;
+      if (entry != root && !IsRetainingEdge(&children[i])) continue;
       HeapEntry* child = children[i].to();
       if (!child->painted()) {
         nodes_to_visit.Add(child);
@@ -3319,6 +3357,7 @@ bool HeapSnapshotGenerator::BuildDominatorTree(
     const Vector<HeapEntry*>& entries,
     Vector<int>* dominators) {
   if (entries.length() == 0) return true;
+  HeapEntry* root = snapshot_->root();
   const int entries_length = entries.length(), root_index = entries_length - 1;
   static const int kNoDominator = -1;
   for (int i = 0; i < root_index; ++i) (*dominators)[i] = kNoDominator;
@@ -3347,8 +3386,8 @@ bool HeapSnapshotGenerator::BuildDominatorTree(
       int new_idom_index = kNoDominator;
       Vector<HeapGraphEdge*> rets = entries[i]->retainers();
       for (int j = 0; j < rets.length(); ++j) {
-        if (rets[j]->type() == HeapGraphEdge::kShortcut) continue;
-        int ret_index = rets[j]->From()->ordered_index();
+        if (rets[j]->from() != root && !IsRetainingEdge(rets[j])) continue;
+        int ret_index = rets[j]->from()->ordered_index();
         if (dominators->at(ret_index) != kNoDominator) {
           new_idom_index = new_idom_index == kNoDominator
               ? ret_index
@@ -3374,9 +3413,10 @@ bool HeapSnapshotGenerator::BuildDominatorTree(
 
 
 bool HeapSnapshotGenerator::SetEntriesDominators() {
-  // This array is used for maintaining reverse postorder of nodes.
+  MarkWindowReachableObjects();
+  // This array is used for maintaining postorder of nodes.
   ScopedVector<HeapEntry*> ordered_entries(snapshot_->entries()->length());
-  FillReversePostorderIndexes(&ordered_entries);
+  FillPostorderIndexes(&ordered_entries);
   ScopedVector<int> dominators(ordered_entries.length());
   if (!BuildDominatorTree(ordered_entries, &dominators)) return false;
   for (int i = 0; i < ordered_entries.length(); ++i) {

src/profile-generator.h

@@ -464,21 +464,20 @@ class HeapGraphEdge BASE_EMBEDDED {
   void Init(int child_index, Type type, int index, HeapEntry* to);
   void Init(int child_index, int index, HeapEntry* to);
 
-  Type type() { return static_cast<Type>(type_); }
-  int index() {
+  Type type() const { return static_cast<Type>(type_); }
+  int index() const {
     ASSERT(type_ == kElement || type_ == kHidden || type_ == kWeak);
     return index_;
   }
-  const char* name() {
+  const char* name() const {
     ASSERT(type_ == kContextVariable
            || type_ == kProperty
            || type_ == kInternal
            || type_ == kShortcut);
     return name_;
   }
-  HeapEntry* to() { return to_; }
-
-  HeapEntry* From();
+  HeapEntry* to() const { return to_; }
+  INLINE(HeapEntry* from() const);
 
  private:
   int child_index_ : 29;
@@ -564,6 +563,8 @@ class HeapEntry BASE_EMBEDDED {
   void clear_paint() { painted_ = false; }
   bool painted() { return painted_; }
   void paint() { painted_ = true; }
+  bool reachable_from_window() { return reachable_from_window_; }
+  void set_reachable_from_window() { reachable_from_window_ = true; }
 
   void SetIndexedReference(HeapGraphEdge::Type type,
                            int child_index,
@@ -600,8 +601,9 @@ class HeapEntry BASE_EMBEDDED {
   const char* TypeAsString();
 
   unsigned painted_: 1;
+  unsigned reachable_from_window_: 1;
   unsigned type_: 4;
-  int children_count_: 27;
+  int children_count_: 26;
   int retainers_count_;
   int self_size_;
   union {
@@ -1016,7 +1018,7 @@ class V8HeapExplorer : public HeapEntriesAllocator {
                                     HeapEntry* parent,
                                     String* reference_name,
                                     Object* child);
-  void SetRootShortcutReference(Object* child);
+  void SetWindowReference(Object* window);
   void SetRootGcRootsReference();
   void SetGcRootsReference(VisitorSynchronization::SyncTag tag);
   void SetGcSubrootReference(
@@ -1120,7 +1122,9 @@ class HeapSnapshotGenerator : public SnapshottingProgressReportingInterface {
   bool CalculateRetainedSizes();
   bool CountEntriesAndReferences();
   bool FillReferences();
-  void FillReversePostorderIndexes(Vector<HeapEntry*>* entries);
+  void FillPostorderIndexes(Vector<HeapEntry*>* entries);
+  bool IsWindowReference(const HeapGraphEdge& edge);
+  void MarkWindowReachableObjects();
   void ProgressStep();
   bool ProgressReport(bool force = false);
   bool SetEntriesDominators();

test/cctest/test-heap-profiler.cc

@@ -109,13 +109,13 @@ TEST(HeapSnapshot) {
 
   // Verify, that JS global object of env2 has '..2' properties.
   const v8::HeapGraphNode* a2_node =
-      GetProperty(global_env2, v8::HeapGraphEdge::kShortcut, "a2");
+      GetProperty(global_env2, v8::HeapGraphEdge::kProperty, "a2");
   CHECK_NE(NULL, a2_node);
   CHECK_NE(
-      NULL, GetProperty(global_env2, v8::HeapGraphEdge::kShortcut, "b2_1"));
+      NULL, GetProperty(global_env2, v8::HeapGraphEdge::kProperty, "b2_1"));
   CHECK_NE(
-      NULL, GetProperty(global_env2, v8::HeapGraphEdge::kShortcut, "b2_2"));
-  CHECK_NE(NULL, GetProperty(global_env2, v8::HeapGraphEdge::kShortcut, "c2"));
+      NULL, GetProperty(global_env2, v8::HeapGraphEdge::kProperty, "b2_2"));
+  CHECK_NE(NULL, GetProperty(global_env2, v8::HeapGraphEdge::kProperty, "c2"));
 
   // Paint all nodes reachable from global object.
   NamedEntriesDetector det;
@@ -137,12 +137,13 @@ TEST(HeapSnapshotObjectSizes) {
   CompileRun(
       "function X(a, b) { this.a = a; this.b = b; }\n"
       "x = new X(new X(), new X());\n"
+      "dummy = new X();\n"
       "(function() { x.a.a = x.b; })();");
   const v8::HeapSnapshot* snapshot =
       v8::HeapProfiler::TakeSnapshot(v8_str("sizes"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* x =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "x");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "x");
   CHECK_NE(NULL, x);
   const v8::HeapGraphNode* x1 =
       GetProperty(x, v8::HeapGraphEdge::kProperty, "a");
@@ -169,7 +170,7 @@ TEST(BoundFunctionInSnapshot) {
       v8::HeapProfiler::TakeSnapshot(v8_str("sizes"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* f =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "boundFunction");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "boundFunction");
   CHECK(f);
   CHECK_EQ(v8::String::New("native_bind"), f->GetName());
   const v8::HeapGraphNode* bindings =
@@ -233,15 +234,15 @@ TEST(HeapSnapshotCodeObjects) {
 
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* compiled =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "compiled");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "compiled");
   CHECK_NE(NULL, compiled);
   CHECK_EQ(v8::HeapGraphNode::kClosure, compiled->GetType());
   const v8::HeapGraphNode* lazy =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "lazy");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "lazy");
   CHECK_NE(NULL, lazy);
   CHECK_EQ(v8::HeapGraphNode::kClosure, lazy->GetType());
   const v8::HeapGraphNode* anonymous =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "anonymous");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "anonymous");
   CHECK_NE(NULL, anonymous);
   CHECK_EQ(v8::HeapGraphNode::kClosure, anonymous->GetType());
   v8::String::AsciiValue anonymous_name(anonymous->GetName());
@@ -293,9 +294,9 @@ TEST(HeapSnapshotHeapNumbers) {
   const v8::HeapSnapshot* snapshot =
       v8::HeapProfiler::TakeSnapshot(v8_str("numbers"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
-  CHECK_EQ(NULL, GetProperty(global, v8::HeapGraphEdge::kShortcut, "a"));
+  CHECK_EQ(NULL, GetProperty(global, v8::HeapGraphEdge::kProperty, "a"));
   const v8::HeapGraphNode* b =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "b");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "b");
   CHECK_NE(NULL, b);
   CHECK_EQ(v8::HeapGraphNode::kHeapNumber, b->GetType());
 }
@@ -313,10 +314,10 @@ TEST(HeapSnapshotSlicedString) {
       v8::HeapProfiler::TakeSnapshot(v8_str("strings"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* parent_string =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "parent_string");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "parent_string");
   CHECK_NE(NULL, parent_string);
   const v8::HeapGraphNode* child_string =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "child_string");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "child_string");
   CHECK_NE(NULL, child_string);
   const v8::HeapGraphNode* parent =
       GetProperty(child_string, v8::HeapGraphEdge::kInternal, "parent");
@@ -384,24 +385,17 @@ TEST(HeapEntryIdsAndArrayShift) {
   const v8::HeapGraphNode* a1 =
       GetProperty(global1, v8::HeapGraphEdge::kProperty, "a");
   CHECK_NE(NULL, a1);
-  const v8::HeapGraphNode* e1 =
-      GetProperty(a1, v8::HeapGraphEdge::kHidden, "1");
-  CHECK_NE(NULL, e1);
   const v8::HeapGraphNode* k1 =
-      GetProperty(e1, v8::HeapGraphEdge::kInternal, "elements");
+      GetProperty(a1, v8::HeapGraphEdge::kInternal, "elements");
   CHECK_NE(NULL, k1);
   const v8::HeapGraphNode* a2 =
       GetProperty(global2, v8::HeapGraphEdge::kProperty, "a");
   CHECK_NE(NULL, a2);
-  const v8::HeapGraphNode* e2 =
-      GetProperty(a2, v8::HeapGraphEdge::kHidden, "1");
-  CHECK_NE(NULL, e2);
   const v8::HeapGraphNode* k2 =
-      GetProperty(e2, v8::HeapGraphEdge::kInternal, "elements");
+      GetProperty(a2, v8::HeapGraphEdge::kInternal, "elements");
   CHECK_NE(NULL, k2);
 
   CHECK_EQ_SNAPSHOT_OBJECT_ID(a1->GetId(), a2->GetId());
-  CHECK_EQ_SNAPSHOT_OBJECT_ID(e1->GetId(), e2->GetId());
   CHECK_EQ_SNAPSHOT_OBJECT_ID(k1->GetId(), k2->GetId());
 }
 
@@ -514,7 +508,7 @@ TEST(HeapEntryDominator) {
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   CHECK_NE(NULL, global);
   const v8::HeapGraphNode* node6 =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "node6");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "node6");
   CHECK_NE(NULL, node6);
   const v8::HeapGraphNode* node5 =
       GetProperty(node6, v8::HeapGraphEdge::kProperty, "a");
@@ -659,7 +653,7 @@ TEST(HeapSnapshotJSONSerialization) {
       "    GetChildPosByProperty("
       "      parsed.edges[parsed.nodes[edges_index_offset]"
       "                   + edge_to_node_offset],"
-      "      \"b\", shortcut_type),\n"
+      "      \"b\", property_type),\n"
       "    \"x\", property_type),"
       "  \"s\", property_type)");
   CHECK(!string_obj_pos_val.IsEmpty());
@@ -1153,9 +1147,8 @@ TEST(HeapSnapshotImplicitReferences) {
       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");
+      global_object, v8::HeapGraphEdge::kProperty, "root_object");
   CHECK(obj0);
   CHECK_EQ(v8::HeapGraphNode::kObject, obj0->GetType());
   const v8::HeapGraphNode* obj1 = GetProperty(
@@ -1328,7 +1321,7 @@ TEST(GetHeapValue) {
       env->Global()->GetPrototype().As<v8::Object>();
   CHECK(js_global == global->GetHeapValue());
   const v8::HeapGraphNode* obj = GetProperty(
-      global, v8::HeapGraphEdge::kShortcut, "a");
+      global, v8::HeapGraphEdge::kProperty, "a");
   CHECK(obj->GetHeapValue()->IsObject());
   v8::Local<v8::Object> js_obj = js_global->Get(v8_str("a")).As<v8::Object>();
   CHECK(js_obj == obj->GetHeapValue());
@@ -1357,7 +1350,7 @@ TEST(GetHeapValueForDeletedObject) {
       v8::HeapProfiler::TakeSnapshot(v8_str("snapshot"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* obj = GetProperty(
-      global, v8::HeapGraphEdge::kShortcut, "a");
+      global, v8::HeapGraphEdge::kProperty, "a");
   const v8::HeapGraphNode* prop = GetProperty(
       obj, v8::HeapGraphEdge::kProperty, "p");
   {
@@ -1444,7 +1437,7 @@ TEST(FastCaseGetter) {
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   CHECK_NE(NULL, global);
   const v8::HeapGraphNode* obj1 =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "obj1");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "obj1");
   CHECK_NE(NULL, obj1);
   const v8::HeapGraphNode* getterFunction =
       GetProperty(obj1, v8::HeapGraphEdge::kProperty, "get-propWithGetter");
@@ -1526,7 +1519,7 @@ TEST(SfiAndJsFunctionWeakRefs) {
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   CHECK_NE(NULL, global);
   const v8::HeapGraphNode* fun =
-      GetProperty(global, v8::HeapGraphEdge::kShortcut, "fun");
+      GetProperty(global, v8::HeapGraphEdge::kProperty, "fun");
   CHECK(HasWeakEdge(fun));
   const v8::HeapGraphNode* shared =
       GetProperty(fun, v8::HeapGraphEdge::kInternal, "shared");