Revert "External references should not affect dominance relation."

src/profile-generator.cc

Index: src/profile-generator.cc
diff --git a/src/profile-generator.cc b/src/profile-generator.cc
index 9c253d73fec7457619303f46d02d63de8b2b0e12..683fec15bb98afc281ce2a1b15eb9f4c35e0eb65 100644
--- a/src/profile-generator.cc
+++ b/src/profile-generator.cc
@@ -957,6 +957,11 @@ 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,
@@ -967,7 +972,6 @@ void HeapEntry::Init(HeapSnapshot* snapshot,
   snapshot_ = snapshot;
   type_ = type;
   painted_ = false;
-  reachable_from_window_ = false;
   name_ = name;
   self_size_ = self_size;
   retained_size_ = 0;
@@ -2174,15 +2178,15 @@ 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.
-        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);
+        if (target->IsJSGlobalPropertyCell()) {
+          SetPropertyShortcutReference(js_obj,
+                                       entry,
+                                       String::cast(k),
+                                       JSGlobalPropertyCell::cast(
+                                           target)->value());
         }
       }
     }
@@ -2633,7 +2637,7 @@ void V8HeapExplorer::TagGlobalObjects() {
     Handle<JSGlobalObject> global_obj = enumerator.at(i);
     Object* obj_document;
     if (global_obj->GetProperty(*document_string)->ToObject(&obj_document) &&
-        obj_document->IsJSObject()) {
+       obj_document->IsJSObject()) {
       JSObject* document = JSObject::cast(obj_document);
       Object* obj_url;
       if (document->GetProperty(*url_string)->ToObject(&obj_url) &&
@@ -3187,55 +3191,19 @@ bool HeapSnapshotGenerator::FillReferences() {
 }
 
 
-void HeapSnapshotGenerator::MarkWindowReachableObjects() {
-  List<HeapEntry*> worklist;
-
-  Vector<HeapGraphEdge> children = snapshot_->root()->children();
-  for (int i = 0; i < children.length(); ++i) {
-    if (children[i].type() == HeapGraphEdge::kShortcut) {
-      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(
+void HeapSnapshotGenerator::FillReversePostorderIndexes(
     Vector<HeapEntry*>* entries) {
   snapshot_->ClearPaint();
   int current_entry = 0;
   List<HeapEntry*> nodes_to_visit;
-  HeapEntry* root = snapshot_->root();
-  nodes_to_visit.Add(root);
+  nodes_to_visit.Add(snapshot_->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 (entry != root && !IsRetainingEdge(&children[i])) continue;
+      if (children[i].type() == HeapGraphEdge::kShortcut) continue;
       HeapEntry* child = children[i].to();
       if (!child->painted()) {
         nodes_to_visit.Add(child);
@@ -3270,7 +3238,6 @@ 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;
@@ -3299,8 +3266,8 @@ 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]->from() != root && !IsRetainingEdge(rets[j])) continue;
-        int ret_index = rets[j]->from()->ordered_index();
+        if (rets[j]->type() == HeapGraphEdge::kShortcut) continue;
+        int ret_index = rets[j]->From()->ordered_index();
         if (dominators->at(ret_index) != kNoDominator) {
           new_idom_index = new_idom_index == kNoDominator
               ? ret_index
@@ -3326,10 +3293,9 @@ bool HeapSnapshotGenerator::BuildDominatorTree(
 
 
 bool HeapSnapshotGenerator::SetEntriesDominators() {
-  MarkWindowReachableObjects();
-  // This array is used for maintaining postorder of nodes.
+  // This array is used for maintaining reverse postorder of nodes.
   ScopedVector<HeapEntry*> ordered_entries(snapshot_->entries()->length());
-  FillPostorderIndexes(&ordered_entries);
+  FillReversePostorderIndexes(&ordered_entries);
   ScopedVector<int> dominators(ordered_entries.length());
   if (!BuildDominatorTree(ordered_entries, &dominators)) return false;
   for (int i = 0; i < ordered_entries.length(); ++i) {