// 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/utils/address-map.h"

#include "src/execution/isolate.h"

#include "src/roots/roots-inl.h"

namespace v8 {

namespace internal {

RootIndexMap::RootIndexMap(Isolate* isolate) {

map_ = isolate->root_index_map();

if (map_ != nullptr) return;

map_ = new HeapObjectToIndexHashMap();

for (RootIndex root_index = RootIndex::kFirstStrongOrReadOnlyRoot;

root_index <= RootIndex::kLastStrongOrReadOnlyRoot; ++root_index) {

Tagged<Object> root = isolate->root(root_index);

if (!IsHeapObject(root)) 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 (RootsTable::IsImmortalImmovable(root_index)) {

Tagged<HeapObject> heap_object = Cast<HeapObject>(root);

Maybe<uint32_t> maybe_index = map_->Get(heap_object);

uint32_t index = static_cast<uint32_t>(root_index);

if (maybe_index.IsJust()) {

// Some are initialized to a previous value in the root list.

DCHECK_LT(maybe_index.FromJust(), index);

} else {

map_->Set(heap_object, index);

}

}

}

isolate->set_root_index_map(map_);

}

} // namespace internal

} // namespace v8