Use a plain FixedArray rather than a SeededNumberDictionary for ValueDeserializer::id_map_.

src/value-serializer.cc

 // Copyright 2016 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/value-serializer.h"
 
 #include <type_traits>
 
 #include "src/base/logging.h"
 #include "src/conversions.h"
@@ skipping 766 matching lines @@
 }
 
 ValueDeserializer::ValueDeserializer(Isolate* isolate,
                                      Vector<const uint8_t> data,
                                      v8::ValueDeserializer::Delegate* delegate)
     : isolate_(isolate),
       delegate_(delegate),
       position_(data.start()),
       end_(data.start() + data.length()),
       pretenure_(data.length() > kPretenureThreshold ? TENURED : NOT_TENURED),
-      id_map_(Handle<SeededNumberDictionary>::cast(
-          isolate->global_handles()->Create(
-              *SeededNumberDictionary::New(isolate, 0)))) {}
+      id_map_(Handle<FixedArray>::cast(isolate->global_handles()->Create(
+          isolate_->heap()->empty_fixed_array()))) {}
 
 ValueDeserializer::~ValueDeserializer() {
   GlobalHandles::Destroy(Handle<Object>::cast(id_map_).location());
 
   Handle<Object> transfer_map_handle;
   if (array_buffer_transfer_map_.ToHandle(&transfer_map_handle)) {
     GlobalHandles::Destroy(transfer_map_handle.location());
   }
 }
 
@@ skipping 768 matching lines @@
         isolate_, object, key, &success, LookupIterator::OWN);
     if (!success ||
         JSObject::DefineOwnPropertyIgnoreAttributes(&it, value, NONE)
             .is_null()) {
       return Nothing<uint32_t>();
     }
   }
 }
 
 bool ValueDeserializer::HasObjectWithID(uint32_t id) {
-  return id_map_->Has(isolate_, id);
+  return static_cast<unsigned>(id_map_->length()) > id &&
+         id_map_->get(id) != isolate_->heap()->the_hole_value();

[Camillo Bruni, 2016/09/16 20:49:37]

nit: use IsTheHole(isolate_)

[jbroman, 2016/09/17 05:00:51]

Done.

 }
 
 MaybeHandle<JSReceiver> ValueDeserializer::GetObjectWithID(uint32_t id) {
-  int index = id_map_->FindEntry(isolate_, id);
-  if (index == SeededNumberDictionary::kNotFound) {
+  if (id >= static_cast<unsigned>(id_map_->length())) {
     return MaybeHandle<JSReceiver>();
   }
-  Object* value = id_map_->ValueAt(index);
+  Object* value = id_map_->get(id);
+  if (value == isolate_->heap()->the_hole_value()) {

[Camillo Bruni, 2016/09/16 20:49:37]

nit: use IsTheHole(isolate_)

[jbroman, 2016/09/17 05:00:51]

Done.

+    return MaybeHandle<JSReceiver>();
+  }
   DCHECK(value->IsJSReceiver());
   return Handle<JSReceiver>(JSReceiver::cast(value), isolate_);
 }
 
 void ValueDeserializer::AddObjectWithID(uint32_t id,
                                         Handle<JSReceiver> object) {
   DCHECK(!HasObjectWithID(id));
-  const bool used_as_prototype = false;
-  Handle<SeededNumberDictionary> new_dictionary =
-      SeededNumberDictionary::AtNumberPut(id_map_, id, object,
-                                          used_as_prototype);
+  Handle<FixedArray> new_array = FixedArray::SetAndGrow(id_map_, id, object);
 
   // If the dictionary was reallocated, update the global handle.
-  if (!new_dictionary.is_identical_to(id_map_)) {
+  if (!new_array.is_identical_to(id_map_)) {
     GlobalHandles::Destroy(Handle<Object>::cast(id_map_).location());
-    id_map_ = Handle<SeededNumberDictionary>::cast(
-        isolate_->global_handles()->Create(*new_dictionary));
+    id_map_ = Handle<FixedArray>::cast(
+        isolate_->global_handles()->Create(*new_array));
   }
 }
 
 static Maybe<bool> SetPropertiesFromKeyValuePairs(Isolate* isolate,
                                                   Handle<JSObject> object,
                                                   Handle<Object>* data,
                                                   uint32_t num_properties) {
   for (unsigned i = 0; i < 2 * num_properties; i += 2) {
     Handle<Object> key = data[i];
     Handle<Object> value = data[i + 1];
@@ skipping 98 matching lines @@
   if (stack.size() != 1) {
     isolate_->Throw(*isolate_->factory()->NewError(
         MessageTemplate::kDataCloneDeserializationError));
     return MaybeHandle<Object>();
   }
   return scope.CloseAndEscape(stack[0]);
 }
 
 }  // namespace internal
 }  // namespace v8