Initial implementation of dedicated FixedArray processing.

FixedArrays could be shown differently based on their subtypes.

Review-Url: https://codereview.chromium.org/2208753002
Cr-Commit-Position: refs/heads/master@{#38351}

src/profiler/heap-snapshot-generator.cc

@@ -1193,16 +1193,16 @@ void V8HeapExplorer::ExtractJSCollectionReferences(int entry,
                        JSCollection::kTableOffset);
 }
 
-
-void V8HeapExplorer::ExtractJSWeakCollectionReferences(
-    int entry, JSWeakCollection* collection) {
-  MarkAsWeakContainer(collection->table());
-  SetInternalReference(collection, entry,
-                       "table", collection->table(),
+void V8HeapExplorer::ExtractJSWeakCollectionReferences(int entry,
+                                                       JSWeakCollection* obj) {
+  if (obj->table()->IsHashTable()) {
+    ObjectHashTable* table = ObjectHashTable::cast(obj->table());
+    TagFixedArraySubType(table, JS_WEAK_COLLECTION_SUB_TYPE);
+  }
+  SetInternalReference(obj, entry, "table", obj->table(),
                        JSWeakCollection::kTableOffset);
 }
 
-
 void V8HeapExplorer::ExtractContextReferences(int entry, Context* context) {
   if (context == context->declaration_context()) {
     ScopeInfo* scope_info = context->closure()->shared()->scope_info();
@@ -1529,20 +1529,33 @@ void V8HeapExplorer::ExtractJSArrayBufferReferences(
                              entry, "backing_store", data_entry);
 }
 
-
 void V8HeapExplorer::ExtractFixedArrayReferences(int entry, FixedArray* array) {
-  bool is_weak = weak_containers_.Contains(array);
+  auto it = array_types_.find(array);
+  if (it == array_types_.end()) {
     for (int i = 0, l = array->length(); i < l; ++i) {
-    if (is_weak) {
-      SetWeakReference(array, entry,
-                       i, array->get(i), array->OffsetOfElementAt(i));
-    } else {
-      SetInternalReference(array, entry,
-                           i, array->get(i), array->OffsetOfElementAt(i));
+      SetInternalReference(array, entry, i, array->get(i),
+                           array->OffsetOfElementAt(i));
     }
+    return;
   }
-}
+  switch (it->second) {
+    case JS_WEAK_COLLECTION_SUB_TYPE:
+      for (int i = 0, l = array->length(); i < l; ++i) {
+        SetWeakReference(array, entry, i, array->get(i),
+                         array->OffsetOfElementAt(i));
+      }
+      break;
 
+    // TODO(alph): Add special processing for other types of FixedArrays.
+
+    default:
+      for (int i = 0, l = array->length(); i < l; ++i) {
+        SetInternalReference(array, entry, i, array->get(i),
+                             array->OffsetOfElementAt(i));
+      }
+      break;
+  }
+}
 
 void V8HeapExplorer::ExtractPropertyReferences(JSObject* js_obj, int entry) {
   Isolate* isolate = js_obj->GetIsolate();
@@ -2128,14 +2141,12 @@ void V8HeapExplorer::TagObject(Object* obj, const char* tag) {
   }
 }
 
-
-void V8HeapExplorer::MarkAsWeakContainer(Object* object) {
-  if (IsEssentialObject(object) && object->IsFixedArray()) {
-    weak_containers_.Insert(object);
-  }
+void V8HeapExplorer::TagFixedArraySubType(const FixedArray* array,
+                                          FixedArraySubInstanceType type) {
+  DCHECK(array_types_.find(array) == array_types_.end());
+  array_types_[array] = type;
 }
 
-
 class GlobalObjectsEnumerator : public ObjectVisitor {
  public:
   void VisitPointers(Object** start, Object** end) override {

src/profiler/heap-snapshot-generator.h

@@ -5,6 +5,8 @@
 #ifndef V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 #define V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 
+#include <unordered_map>
+
 #include "include/v8-profiler.h"
 #include "src/base/platform/time.h"
 #include "src/objects.h"
@@ -453,7 +455,8 @@ class V8HeapExplorer : public HeapEntriesAllocator {
       VisitorSynchronization::SyncTag tag, bool is_weak, Object* child);
   const char* GetStrongGcSubrootName(Object* object);
   void TagObject(Object* obj, const char* tag);
-  void MarkAsWeakContainer(Object* object);
+  void TagFixedArraySubType(const FixedArray* array,
+                            FixedArraySubInstanceType type);
 
   HeapEntry* GetEntry(Object* obj);
 
@@ -466,7 +469,7 @@ class V8HeapExplorer : public HeapEntriesAllocator {
   HeapObjectsSet objects_tags_;
   HeapObjectsSet strong_gc_subroot_names_;
   HeapObjectsSet user_roots_;
-  HeapObjectsSet weak_containers_;
+  std::unordered_map<const FixedArray*, FixedArraySubInstanceType> array_types_;
   v8::HeapProfiler::ObjectNameResolver* global_object_name_resolver_;
 
   std::vector<bool> marks_;