1 files changed, 46 insertions, 0 deletions
diff --git a/deps/v8/src/utils/address-map.cc b/deps/v8/src/utils/address-map.cc
new file mode 100644
index 0000000000..ab32ba418a
--- /dev/null
+++ b/deps/v8/src/utils/address-map.cc
@@ -0,0 +1,46 @@
+// 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/heap/heap.h"
+#include "src/objects/heap-object-inl.h"
+#include "src/objects/objects-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) {
+    Object root = isolate->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 (RootsTable::IsImmortalImmovable(root_index)) {
+      HeapObject heap_object = HeapObject::cast(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_);
+}
+
+bool RootIndexMap::Lookup(Address obj, RootIndex* out_root_list) const {
+  return Lookup(HeapObject::cast(Object(obj)), out_root_list);
+}
+
+}  // namespace internal
+}  // namespace v8