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// Copyright 2022 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.
#ifndef V8_CODEGEN_BACKGROUND_MERGE_TASK_H_
#define V8_CODEGEN_BACKGROUND_MERGE_TASK_H_
#include <vector>
#include "src/handles/maybe-handles.h"
namespace v8 {
namespace internal {
class FeedbackMetadata;
class PersistentHandles;
class Script;
class SharedFunctionInfo;
class String;
struct ScriptDetails;
// Contains data transferred between threads for background merging between a
// newly compiled or deserialized script and an existing script from the Isolate
// compilation cache.
class V8_EXPORT_PRIVATE BackgroundMergeTask {
public:
~BackgroundMergeTask();
// Step 1: on the main thread, check whether the Isolate compilation cache
// contains the script.
void SetUpOnMainThread(Isolate* isolate, Handle<String> source_text,
const ScriptDetails& script_details,
LanguageMode language_mode);
// Step 2: on the background thread, update pointers in the new Script's
// object graph to point to corresponding objects from the cached Script where
// appropriate. May only be called if HasPendingBackgroundWork returned true.
void BeginMergeInBackground(LocalIsolate* isolate, Handle<Script> new_script);
// Step 3: on the main thread again, complete the merge so that all relevant
// objects are reachable from the cached Script. May only be called if
// HasPendingForegroundWork returned true. Returns the top-level
// SharedFunctionInfo that should be used.
Handle<SharedFunctionInfo> CompleteMergeInForeground(
Isolate* isolate, Handle<Script> new_script);
bool HasPendingBackgroundWork() const {
return state_ == kPendingBackgroundWork;
}
bool HasPendingForegroundWork() const {
return state_ == kPendingForegroundWork;
}
private:
std::unique_ptr<PersistentHandles> persistent_handles_;
// Data from main thread:
MaybeHandle<Script> cached_script_;
// Data from background thread:
// The top-level SharedFunctionInfo from the cached script, if one existed,
// just to keep it alive.
MaybeHandle<SharedFunctionInfo> toplevel_sfi_from_cached_script_;
// New SharedFunctionInfos which are used because there was no corresponding
// SharedFunctionInfo in the cached script. The main thread must:
// 1. Check whether the cached script gained corresponding SharedFunctionInfos
// for any of these, and if so, redo the merge.
// 2. Update the cached script's shared_function_infos list to refer to these.
std::vector<Handle<SharedFunctionInfo>> used_new_sfis_;
// SharedFunctionInfos from the cached script which were not compiled, with
// function_data and feedback_metadata from the corresponding new
// SharedFunctionInfo. If the SharedFunctionInfo from the cached script is
// still uncompiled when finishing, the main thread must set the two fields.
struct NewCompiledDataForCachedSfi {
Handle<SharedFunctionInfo> cached_sfi;
Handle<Object> function_data;
Handle<FeedbackMetadata> feedback_metadata;
};
std::vector<NewCompiledDataForCachedSfi> new_compiled_data_for_cached_sfis_;
enum State {
kNotStarted,
kPendingBackgroundWork,
kPendingForegroundWork,
kDone,
};
State state_ = kNotStarted;
};
} // namespace internal
} // namespace v8
#endif // V8_CODEGEN_BACKGROUND_MERGE_TASK_H_
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