1// Copyright 2015 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/address-map.h"
6#include "src/heap/heap.h"
7#include "src/isolate.h"
8#include "src/objects-inl.h"
9#include "src/objects/heap-object-inl.h"
10
11namespace v8 {
12namespace internal {
13
14RootIndexMap::RootIndexMap(Isolate* isolate) {
15 map_ = isolate->root_index_map();
16 if (map_ != nullptr) return;
17 map_ = new HeapObjectToIndexHashMap();
18 for (RootIndex root_index = RootIndex::kFirstStrongOrReadOnlyRoot;
19 root_index <= RootIndex::kLastStrongOrReadOnlyRoot; ++root_index) {
20 Object root = isolate->root(root_index);
21 if (!root->IsHeapObject()) continue;
22 // Omit root entries that can be written after initialization. They must
23 // not be referenced through the root list in the snapshot.
24 // Since we map the raw address of an root item to its root list index, the
25 // raw address must be constant, i.e. the object must be immovable.
26 if (RootsTable::IsImmortalImmovable(root_index)) {
27 HeapObject heap_object = HeapObject::cast(root);
28 Maybe<uint32_t> maybe_index = map_->Get(heap_object);
29 uint32_t index = static_cast<uint32_t>(root_index);
30 if (maybe_index.IsJust()) {
31 // Some are initialized to a previous value in the root list.
32 DCHECK_LT(maybe_index.FromJust(), index);
33 } else {
34 map_->Set(heap_object, index);
35 }
36 }
37 }
38 isolate->set_root_index_map(map_);
39}
40
41bool RootIndexMap::Lookup(Address obj, RootIndex* out_root_list) const {
42 return Lookup(HeapObject::cast(Object(obj)), out_root_list);
43}
44
45} // namespace internal
46} // namespace v8
47