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
10namespace v8 {
11namespace internal {
12
13RootIndexMap::RootIndexMap(Isolate* isolate) {
14  map_ = isolate->root_index_map();
15  if (map_ != NULL) return;
16  map_ = new HashMap(HashMap::PointersMatch);
17  for (uint32_t i = 0; i < Heap::kStrongRootListLength; i++) {
18    Heap::RootListIndex root_index = static_cast<Heap::RootListIndex>(i);
19    Object* root = isolate->heap()->root(root_index);
20    // Omit root entries that can be written after initialization. They must
21    // not be referenced through the root list in the snapshot.
22    if (root->IsHeapObject() &&
23        isolate->heap()->RootCanBeTreatedAsConstant(root_index)) {
24      HeapObject* heap_object = HeapObject::cast(root);
25      HashMap::Entry* entry = LookupEntry(map_, heap_object, false);
26      if (entry != NULL) {
27        // Some are initialized to a previous value in the root list.
28        DCHECK_LT(GetValue(entry), i);
29      } else {
30        SetValue(LookupEntry(map_, heap_object, true), i);
31      }
32    }
33  }
34  isolate->set_root_index_map(map_);
35}
36
37}  // namespace internal
38}  // namespace v8
39