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// Copyright 2020 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/snapshot/serializer-deserializer.h"
#include "src/objects/foreign-inl.h"
#include "src/objects/objects-inl.h"
namespace v8 {
namespace internal {
// The startup object cache is terminated by undefined. We visit the context
// snapshot...
// - during deserialization to populate it.
// - during normal GC to keep its content alive.
// - not during serialization. The context serializer adds to it explicitly.
DISABLE_CFI_PERF
void SerializerDeserializer::Iterate(Isolate* isolate, RootVisitor* visitor) {
std::vector<Object>* cache = isolate->startup_object_cache();
for (size_t i = 0;; ++i) {
// Extend the array ready to get a value when deserializing.
if (cache->size() <= i) cache->push_back(Smi::zero());
// During deserialization, the visitor populates the startup object cache
// and eventually terminates the cache with undefined.
visitor->VisitRootPointer(Root::kStartupObjectCache, nullptr,
FullObjectSlot(&cache->at(i)));
if (cache->at(i).IsUndefined(isolate)) break;
}
}
bool SerializerDeserializer::CanBeDeferred(HeapObject o) {
// 1. Maps cannot be deferred as objects are expected to have a valid map
// immediately.
// 2. Internalized strings cannot be deferred as they might be
// converted to thin strings during post processing, at which point forward
// references to the now-thin string will already have been written.
// 3. JS objects with embedder fields cannot be deferred because the
// serialize/deserialize callbacks need the back reference immediately to
// identify the object.
// TODO(leszeks): Could we defer string serialization if forward references
// were resolved after object post processing?
return !o.IsMap() && !o.IsInternalizedString() &&
!(o.IsJSObject() && JSObject::cast(o).GetEmbedderFieldCount() > 0);
}
void SerializerDeserializer::RestoreExternalReferenceRedirector(
Isolate* isolate, Handle<AccessorInfo> accessor_info) {
// Restore wiped accessor infos.
Foreign::cast(accessor_info->js_getter())
.set_foreign_address(isolate, accessor_info->redirected_getter());
}
void SerializerDeserializer::RestoreExternalReferenceRedirector(
Isolate* isolate, Handle<CallHandlerInfo> call_handler_info) {
Foreign::cast(call_handler_info->js_callback())
.set_foreign_address(isolate, call_handler_info->redirected_callback());
}
} // namespace internal
} // namespace v8
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