[heap profiler] Refactor: remove SnapshotFiller proxy

Long time ago there were two passes over heap. One was counting
objects and edge and another was filling them. Since then we have
just a single pass, but the filler object is still there.

Remove it for the sake of layering simplicity.

Change-Id: Ic873eb5ca616b9dcae17fe388197dde8f539026f
Reviewed-on: https://chromium-review.googlesource.com/1244380
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56246}

src/profiler/heap-snapshot-generator.h

@@ -29,6 +29,7 @@ class HeapEntry;
 class HeapIterator;
 class HeapProfiler;
 class HeapSnapshot;
+class HeapSnapshotGenerator;
 class JSArrayBuffer;
 class JSCollection;
 class JSGeneratorObject;
@@ -36,7 +37,6 @@ class JSGlobalObject;
 class JSGlobalProxy;
 class JSPromise;
 class JSWeakCollection;
-class SnapshotFiller;
 
 struct SourceLocation {
   SourceLocation(int entry_index, int scriptId, int line, int col)
@@ -136,6 +136,13 @@ class HeapEntry {
       HeapGraphEdge::Type type, int index, HeapEntry* entry);
   void SetNamedReference(
       HeapGraphEdge::Type type, const char* name, HeapEntry* entry);
+  void SetIndexedAutoIndexReference(HeapGraphEdge::Type type,
+                                    HeapEntry* child) {
+    SetIndexedReference(type, children_count_ + 1, child);
+  }
+  void SetNamedAutoIndexReference(HeapGraphEdge::Type type,
+                                  const char* description, HeapEntry* child,
+                                  StringsStorage* strings);
 
   void Print(
       const char* prefix, const char* edge_name, int max_depth, int indent);
@@ -310,9 +317,10 @@ class V8HeapExplorer : public HeapEntriesAllocator {
                  SnapshottingProgressReportingInterface* progress,
                  v8::HeapProfiler::ObjectNameResolver* resolver);
   ~V8HeapExplorer() override = default;
+
   HeapEntry* AllocateEntry(HeapThing ptr) override;
   int EstimateObjectsCount();
-  bool IterateAndExtractReferences(SnapshotFiller* filler);
+  bool IterateAndExtractReferences(HeapSnapshotGenerator* generator);
   void TagGlobalObjects();
   void TagCodeObject(Code* code);
   void TagBuiltinCodeObject(Code* code, const char* name);
@@ -425,7 +433,7 @@ class V8HeapExplorer : public HeapEntriesAllocator {
   StringsStorage* names_;
   HeapObjectsMap* heap_object_map_;
   SnapshottingProgressReportingInterface* progress_;
-  SnapshotFiller* filler_;
+  HeapSnapshotGenerator* generator_ = nullptr;
   std::unordered_map<JSGlobalObject*, const char*> objects_tags_;
   std::unordered_map<Object*, const char*> strong_gc_subroot_names_;
   std::unordered_set<JSGlobalObject*> user_roots_;
@@ -450,7 +458,7 @@ class NativeObjectsExplorer {
                         SnapshottingProgressReportingInterface* progress);
   virtual ~NativeObjectsExplorer();
   int EstimateObjectsCount();
-  bool IterateAndExtractReferences(SnapshotFiller* filler);
+  bool IterateAndExtractReferences(HeapSnapshotGenerator* generator);
 
  private:
   void FillRetainedObjects();
@@ -494,7 +502,7 @@ class NativeObjectsExplorer {
   std::unique_ptr<HeapEntriesAllocator> native_entries_allocator_;
   std::unique_ptr<HeapEntriesAllocator> embedder_graph_entries_allocator_;
   // Used during references extraction.
-  SnapshotFiller* filler_;
+  HeapSnapshotGenerator* generator_ = nullptr;
   v8::HeapProfiler::RetainerEdges edges_;
 
   static HeapThing const kNativesRootObject;
@@ -504,7 +512,6 @@ class NativeObjectsExplorer {
   DISALLOW_COPY_AND_ASSIGN(NativeObjectsExplorer);
 };
 
-
 class HeapSnapshotGenerator : public SnapshottingProgressReportingInterface {
  public:
   // The HeapEntriesMap instance is used to track a mapping between
@@ -517,6 +524,21 @@ class HeapSnapshotGenerator : public SnapshottingProgressReportingInterface {
                         Heap* heap);
   bool GenerateSnapshot();
 
+  HeapEntry* FindEntry(HeapThing ptr) {
+    auto it = entries_map_.find(ptr);
+    return it != entries_map_.end() ? it->second : nullptr;
+  }
+
+  HeapEntry* AddEntry(HeapThing ptr, HeapEntriesAllocator* allocator) {
+    return entries_map_.emplace(ptr, allocator->AllocateEntry(ptr))
+        .first->second;
+  }
+
+  HeapEntry* FindOrAddEntry(HeapThing ptr, HeapEntriesAllocator* allocator) {
+    HeapEntry* entry = FindEntry(ptr);
+    return entry != nullptr ? entry : AddEntry(ptr, allocator);
+  }
+
  private:
   bool FillReferences();
   void ProgressStep() override;