Do not report unessential weak references in heap snapshot.

R=verwaest@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/19267023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15731 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap-snapshot-generator.cc

@@ -1681,13 +1681,14 @@ void V8HeapExplorer::SetWeakReference(HeapObject* parent_obj,
                                       int field_offset) {
   ASSERT(parent_entry == GetEntry(parent_obj)->index());
   HeapEntry* child_entry = GetEntry(child_obj);
-  if (child_entry != NULL) {
+  if (child_entry == NULL) return;
+  if (IsEssentialObject(child_obj)) {
     filler_->SetIndexedReference(HeapGraphEdge::kWeak,
                                  parent_entry,
                                  index,
                                  child_entry);
-    IndexedReferencesExtractor::MarkVisitedField(parent_obj, field_offset);
   }
+  IndexedReferencesExtractor::MarkVisitedField(parent_obj, field_offset);
 }
 
 

test/cctest/test-heap-profiler.cc

@@ -1728,27 +1728,6 @@ TEST(WeakGlobalHandle) {
 }
 
 
-TEST(WeakNativeContextRefs) {
-  LocalContext env;
-  v8::HandleScope scope(env->GetIsolate());
-  v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
-
-  const v8::HeapSnapshot* snapshot =
-      heap_profiler->TakeHeapSnapshot(v8_str("weaks"));
-  CHECK(ValidateSnapshot(snapshot));
-  const v8::HeapGraphNode* gc_roots = GetNode(
-      snapshot->GetRoot(), v8::HeapGraphNode::kSynthetic, "(GC roots)");
-  CHECK_NE(NULL, gc_roots);
-  const v8::HeapGraphNode* global_handles = GetNode(
-      gc_roots, v8::HeapGraphNode::kSynthetic, "(Global handles)");
-  CHECK_NE(NULL, global_handles);
-  const v8::HeapGraphNode* native_context = GetNode(
-      global_handles, v8::HeapGraphNode::kHidden, "system / NativeContext");
-  CHECK_NE(NULL, native_context);
-  CHECK(HasWeakEdge(native_context));
-}
-
-
 TEST(SfiAndJsFunctionWeakRefs) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());
@@ -1763,10 +1742,10 @@ TEST(SfiAndJsFunctionWeakRefs) {
   CHECK_NE(NULL, global);
   const v8::HeapGraphNode* fun =
       GetProperty(global, v8::HeapGraphEdge::kProperty, "fun");
-  CHECK(HasWeakEdge(fun));
+  CHECK(!HasWeakEdge(fun));
   const v8::HeapGraphNode* shared =
       GetProperty(fun, v8::HeapGraphEdge::kInternal, "shared");
-  CHECK(HasWeakEdge(shared));
+  CHECK(!HasWeakEdge(shared));
 }