Avoid some crashes when running without snapshots.

src/profile-generator.cc

 // Copyright 2011 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 1768 matching lines @@
     case NAME##_TYPE: return "system / "#Name;
   STRUCT_LIST(MAKE_STRUCT_CASE)
 #undef MAKE_STRUCT_CASE
     default: return "system";
   }
 }
 
 
 int V8HeapExplorer::EstimateObjectsCount(HeapIterator* iterator) {
   int objects_count = 0;
-  for (HeapObject* obj = iterator->Next();
+  for (HeapObject* obj = iterator->next();
        obj != NULL;
-       obj = iterator->Next(), ++objects_count) {}
+       obj = iterator->next()) {
+    objects_count++;
+  }
   return objects_count;
 }
 
 
 class IndexedReferencesExtractor : public ObjectVisitor {
  public:
   IndexedReferencesExtractor(V8HeapExplorer* generator,
                              HeapObject* parent_obj,
                              HeapEntry* parent_entry)
       : generator_(generator),
@@ skipping 319 matching lines @@
   }
   void VisitPointers(Object** start, Object** end) {
     for (Object** p = start; p < end; p++) explorer_->SetGcRootsReference(*p);
   }
  private:
   V8HeapExplorer* explorer_;
 };
 
 
 bool V8HeapExplorer::IterateAndExtractReferences(
-    HeapIterator* iterator,
     SnapshotFillerInterface* filler) {
+  HeapIterator iterator(HeapIterator::kFilterUnreachable);
+
   filler_ = filler;
   bool interrupted = false;
 
   // Heap iteration with filtering must be finished in any case.
-  for (HeapObject* obj = iterator->Next();
+  for (HeapObject* obj = iterator.next();
        obj != NULL;
-       obj = iterator->Next(), progress_->ProgressStep()) {
+       obj = iterator.next(), progress_->ProgressStep()) {
     if (!interrupted) {
       ExtractReferences(obj);
       if (!progress_->ProgressReport(false)) interrupted = true;
     }
   }
   if (interrupted) {
     filler_ = NULL;
     return false;
   }
   SetRootGcRootsReference();
@@ skipping 548 matching lines @@
 bool HeapSnapshotGenerator::GenerateSnapshot() {
   v8_heap_explorer_.TagGlobalObjects();
 
   // TODO(gc) Profiler assumes that any object that is in the heap after
   // full GC is reachable from the root when computing dominators.
   // This is not true for weakly reachable objects.
   // As a temporary solution we call GC twice.
   Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
   Isolate::Current()->heap()->CollectAllGarbage(Heap::kMakeHeapIterableMask);
 
-  // Iterator creation should follow TagGlobalObjects as it can allocate.
-  HeapIterator set_progress_heap_iterator;
-  HeapIterator count_entries_heap_iterator;
-  HeapIterator fill_references_heap_iterator;
+#ifdef DEBUG
+  Heap* debug_heap = Isolate::Current()->heap();
+  ASSERT(!debug_heap->old_data_space()->was_swept_conservatively());
+  ASSERT(!debug_heap->old_pointer_space()->was_swept_conservatively());
+  ASSERT(!debug_heap->code_space()->was_swept_conservatively());
+  ASSERT(!debug_heap->cell_space()->was_swept_conservatively());
+  ASSERT(!debug_heap->map_space()->was_swept_conservatively());
+#endif
 
+  // The following code uses heap iterators, so we want the heap to be
+  // stable. It should follow TagGlobalObjects as that can allocate.
   AssertNoAllocation no_alloc;
 
-  SetProgressTotal(&set_progress_heap_iterator,
-                   4);  // 2 passes + dominators + sizes.
+#ifdef DEBUG
+  debug_heap->Verify();
+#endif
+
+  SetProgressTotal(4);  // 2 passes + dominators + sizes.
+
+#ifdef DEBUG
+  debug_heap->Verify();
+#endif
 
   // Pass 1. Iterate heap contents to count entries and references.
-  if (!CountEntriesAndReferences(&count_entries_heap_iterator)) return false;
+  if (!CountEntriesAndReferences()) return false;
+
+#ifdef DEBUG
+  debug_heap->Verify();
+#endif
 
   // Allocate and fill entries in the snapshot, allocate references.
   snapshot_->AllocateEntries(entries_.entries_count(),
                              entries_.total_children_count(),
                              entries_.total_retainers_count());
   entries_.AllocateEntries();
 
   // Pass 2. Fill references.
-  if (!FillReferences(&fill_references_heap_iterator)) return false;
+  if (!FillReferences()) return false;
 
   if (!SetEntriesDominators()) return false;
   if (!ApproximateRetainedSizes()) return false;
 
   progress_counter_ = progress_total_;
   if (!ProgressReport(true)) return false;
   return true;
 }
 
 
 void HeapSnapshotGenerator::ProgressStep() {
   ++progress_counter_;
 }
 
 
 bool HeapSnapshotGenerator::ProgressReport(bool force) {
   const int kProgressReportGranularity = 10000;
   if (control_ != NULL
       && (force || progress_counter_ % kProgressReportGranularity == 0)) {
       return
           control_->ReportProgressValue(progress_counter_, progress_total_) ==
           v8::ActivityControl::kContinue;
   }
   return true;
 }
 
 
-void HeapSnapshotGenerator::SetProgressTotal(HeapIterator* iterator,
-                                             int iterations_count) {
+void HeapSnapshotGenerator::SetProgressTotal(int iterations_count) {
   if (control_ == NULL) return;
+  HeapIterator iterator(HeapIterator::kFilterUnreachable);
   progress_total_ = (
-      v8_heap_explorer_.EstimateObjectsCount(iterator) +
+      v8_heap_explorer_.EstimateObjectsCount(&iterator) +
       dom_explorer_.EstimateObjectsCount()) * iterations_count;
   progress_counter_ = 0;
 }
 
 
-bool HeapSnapshotGenerator::CountEntriesAndReferences(HeapIterator* iterator) {
+bool HeapSnapshotGenerator::CountEntriesAndReferences() {
   SnapshotCounter counter(&entries_);
   v8_heap_explorer_.AddRootEntries(&counter);
   dom_explorer_.AddRootEntries(&counter);
   return
-      v8_heap_explorer_.IterateAndExtractReferences(iterator, &counter) &&
+      v8_heap_explorer_.IterateAndExtractReferences(&counter) &&
       dom_explorer_.IterateAndExtractReferences(&counter);
 }
 
 
-bool HeapSnapshotGenerator::FillReferences(HeapIterator* iterator) {
+bool HeapSnapshotGenerator::FillReferences() {
   SnapshotFiller filler(snapshot_, &entries_);
   return
-      v8_heap_explorer_.IterateAndExtractReferences(iterator, &filler) &&
+      v8_heap_explorer_.IterateAndExtractReferences(&filler) &&
       dom_explorer_.IterateAndExtractReferences(&filler);
 }
 
 
 void HeapSnapshotGenerator::FillReversePostorderIndexes(
     Vector<HeapEntry*>* entries) {
   snapshot_->ClearPaint();
   int current_entry = 0;
   List<HeapEntry*> nodes_to_visit;
   nodes_to_visit.Add(snapshot_->root());
@@ skipping 10 matching lines @@
         child->paint_reachable();
         has_new_edges = true;
       }
     }
     if (!has_new_edges) {
       entry->set_ordered_index(current_entry);
       (*entries)[current_entry++] = entry;
       nodes_to_visit.RemoveLast();
     }
   }
-  entries->Truncate(current_entry);
+  ASSERT_EQ(current_entry, entries->length());
 }
 
 
 static int Intersect(int i1, int i2, const Vector<HeapEntry*>& dominators) {
   int finger1 = i1, finger2 = i2;
   while (finger1 != finger2) {
     while (finger1 < finger2) finger1 = dominators[finger1]->ordered_index();
     while (finger2 < finger1) finger2 = dominators[finger2]->ordered_index();
   }
   return finger1;
@@ skipping 451 matching lines @@
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 
 String* GetConstructorNameForHeapProfile(JSObject* object) {
   if (object->IsJSFunction()) return HEAP->closure_symbol();
   return object->constructor_name();
 }
 
 } }  // namespace v8::internal