// Copyright 2015 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/address-map.h" #include "src/heap/heap.h" #include "src/isolate.h" #include "src/objects-inl.h" namespace v8 { namespace internal { RootIndexMap::RootIndexMap(Isolate* isolate) { map_ = isolate->root_index_map(); if (map_ != nullptr) return; map_ = new HeapObjectToIndexHashMap(); for (uint32_t i = 0; i < Heap::kStrongRootListLength; i++) { Heap::RootListIndex root_index = static_cast<Heap::RootListIndex>(i); Object* root = isolate->heap()->root(root_index); if (!root->IsHeapObject()) continue; // Omit root entries that can be written after initialization. They must // not be referenced through the root list in the snapshot. // Since we map the raw address of an root item to its root list index, the // raw address must be constant, i.e. the object must be immovable. if (isolate->heap()->RootCanBeTreatedAsConstant(root_index)) { HeapObject* heap_object = HeapObject::cast(root); Maybe<uint32_t> maybe_index = map_->Get(heap_object); if (maybe_index.IsJust()) { // Some are initialized to a previous value in the root list. DCHECK_LT(maybe_index.FromJust(), i); } else { map_->Set(heap_object, i); } } else { // Immortal immovable root objects are constant and allocated on the first // page of old space. Non-constant roots cannot be immortal immovable. The // root index map contains all immortal immmovable root objects. CHECK(!Heap::RootIsImmortalImmovable(root_index)); } } isolate->set_root_index_map(map_); } } // namespace internal } // namespace v8