Heap profiler: correctly determine equivalence of objects having self-refs.

src/heap-profiler.cc

 // Copyright 2009 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 315 matching lines @@
   js_objects_info_tree_.ForEach(this);
 }
 
 
 void JSObjectsCluster::Print(StringStream* accumulator) const {
   ASSERT(!is_null());
   if (constructor_ == FromSpecialCase(ROOTS)) {
     accumulator->Add("(roots)");
   } else if (constructor_ == FromSpecialCase(GLOBAL_PROPERTY)) {
     accumulator->Add("(global property)");
+  } else if (constructor_ == FromSpecialCase(SELF)) {
+    accumulator->Add("(self)");
   } else {
     SmartPointer<char> s_name(
         constructor_->ToCString(DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL));
     accumulator->Add("%s", (*s_name)[0] != '\0' ? *s_name : "(anonymous)");
     if (instance_ != NULL) {
       accumulator->Add(":%p", static_cast<void*>(instance_));
     }
   }
 }
 
@@ skipping 40 matching lines @@
   if (a.refs.length() > b.refs.length()) return 1;
   for (int i = 0; i < a.refs.length(); ++i) {
     int cmp = JSObjectsCluster::Compare(a.refs[i], b.refs[i]);
     if (cmp != 0) return cmp;
   }
   return 0;
 }
 
 
 ClustersCoarser::ClustersCoarser()
-  : zscope_(DELETE_ON_EXIT),
-    sim_list_(ClustersCoarser::kInitialSimilarityListCapacity),
-    current_pair_(NULL) {
+    : zscope_(DELETE_ON_EXIT),
+      sim_list_(ClustersCoarser::kInitialSimilarityListCapacity),
+      current_pair_(NULL),
+      current_set_(NULL),
+      self_(NULL) {
 }
 
 
 void ClustersCoarser::Call(const JSObjectsCluster& cluster,
                            JSObjectsClusterTree* tree) {
   if (!cluster.can_be_coarsed()) return;
   ClusterBackRefs pair(cluster);
   ASSERT(current_pair_ == NULL);
   current_pair_ = &pair;
   current_set_ = new JSObjectsRetainerTree();
+  self_ = &cluster;
   tree->ForEach(this);
   sim_list_.Add(pair);
   current_pair_ = NULL;
   current_set_ = NULL;
+  self_ = NULL;
 }
 
 
 void ClustersCoarser::Call(const JSObjectsCluster& cluster,
                            const NumberAndSizeInfo& number_and_size) {
   ASSERT(current_pair_ != NULL);
   ASSERT(current_set_ != NULL);
+  ASSERT(self_ != NULL);
+  JSObjectsRetainerTree::Locator loc;
+  if (JSObjectsCluster::Compare(*self_, cluster) == 0) {
+    current_pair_->refs.Add(JSObjectsCluster(JSObjectsCluster::SELF));
+    return;
+  }
   JSObjectsCluster eq = GetCoarseEquivalent(cluster);
-  JSObjectsRetainerTree::Locator loc;
   if (!eq.is_null()) {
     if (current_set_->Find(eq, &loc)) return;
     current_pair_->refs.Add(eq);
     current_set_->Insert(eq, &loc);
   } else {
     current_pair_->refs.Add(cluster);
   }
 }
 
 
 void ClustersCoarser::Process(JSObjectsRetainerTree* tree) {
   int last_eq_clusters = -1;
   for (int i = 0; i < kMaxPassesCount; ++i) {
     sim_list_.Clear();
     const int curr_eq_clusters = DoProcess(tree);
     // If no new cluster equivalents discovered, abort processing.
     if (last_eq_clusters == curr_eq_clusters) break;
     last_eq_clusters = curr_eq_clusters;
   }
 }
 
 
 int ClustersCoarser::DoProcess(JSObjectsRetainerTree* tree) {
   tree->ForEach(this);
-  // To sort similarity list properly, references list of a cluster is
-  // required to be sorted, thus 'O1 <- A, B' and 'O2 <- B, A' would
-  // be considered equivalent. But we don't sort them explicitly
-  // because we know that they come from a splay tree traversal, so
-  // they are already sorted.
+  sim_list_.Iterate(ClusterBackRefs::SortRefsIterator);
   sim_list_.Sort(ClusterBackRefsCmp);
   return FillEqualityTree();
 }
 
 
 JSObjectsCluster ClustersCoarser::GetCoarseEquivalent(
     const JSObjectsCluster& cluster) {
   if (!cluster.can_be_coarsed()) return JSObjectsCluster();
   EqualityTree::Locator loc;
   return eq_tree_.Find(cluster, &loc) ? loc.value() : JSObjectsCluster();
@@ skipping 149 matching lines @@
   js_retainer_profile.PrintStats();
 
   LOG(HeapSampleEndEvent("Heap", "allocated"));
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 
 } }  // namespace v8::internal