b01869cabd
Adds GCInfo folding that delegates GCInfo requests to the parent-most object if finalizer semantics match. Folding is disabled for builds that want exact object names as those names are also managed through GCInfo objects. Bug: chromium:1056170 Change-Id: I783aad930587853741da533d0b9b56ba160d0596 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2748588 Commit-Queue: Michael Lippautz <mlippautz@chromium.org> Reviewed-by: Omer Katz <omerkatz@chromium.org> Cr-Commit-Position: refs/heads/master@{#73339}
118 lines
3.3 KiB
C++
118 lines
3.3 KiB
C++
// Copyright 2020 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef INCLUDE_CPPGC_GARBAGE_COLLECTED_H_
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#define INCLUDE_CPPGC_GARBAGE_COLLECTED_H_
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#include <type_traits>
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#include "cppgc/internal/api-constants.h"
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#include "cppgc/platform.h"
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#include "cppgc/trace-trait.h"
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#include "cppgc/type-traits.h"
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namespace cppgc {
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class Visitor;
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namespace internal {
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class GarbageCollectedBase {
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public:
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// Must use MakeGarbageCollected.
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void* operator new(size_t) = delete;
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void* operator new[](size_t) = delete;
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// The garbage collector is taking care of reclaiming the object. Also,
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// virtual destructor requires an unambiguous, accessible 'operator delete'.
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void operator delete(void*) {
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#ifdef V8_ENABLE_CHECKS
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internal::Abort();
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#endif // V8_ENABLE_CHECKS
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}
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void operator delete[](void*) = delete;
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protected:
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GarbageCollectedBase() = default;
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};
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} // namespace internal
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/**
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* Base class for managed objects. Only descendent types of `GarbageCollected`
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* can be constructed using `MakeGarbageCollected()`. Must be inherited from as
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* left-most base class.
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*
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* Types inheriting from GarbageCollected must provide a method of
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* signature `void Trace(cppgc::Visitor*) const` that dispatchs all managed
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* pointers to the visitor and delegates to garbage-collected base classes.
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* The method must be virtual if the type is not directly a child of
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* GarbageCollected and marked as final.
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*
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* \code
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* // Example using final class.
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* class FinalType final : public GarbageCollected<FinalType> {
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* public:
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* void Trace(cppgc::Visitor* visitor) const {
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* // Dispatch using visitor->Trace(...);
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* }
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* };
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*
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* // Example using non-final base class.
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* class NonFinalBase : public GarbageCollected<NonFinalBase> {
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* public:
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* virtual void Trace(cppgc::Visitor*) const {}
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* };
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*
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* class FinalChild final : public NonFinalBase {
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* public:
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* void Trace(cppgc::Visitor* visitor) const final {
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* // Dispatch using visitor->Trace(...);
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* NonFinalBase::Trace(visitor);
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* }
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* };
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* \endcode
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*/
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template <typename T>
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class GarbageCollected : public internal::GarbageCollectedBase {
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public:
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using IsGarbageCollectedTypeMarker = void;
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using ParentMostGarbageCollectedType = T;
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protected:
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GarbageCollected() = default;
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};
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/**
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* Base class for managed mixin objects. Such objects cannot be constructed
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* directly but must be mixed into the inheritance hierarchy of a
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* GarbageCollected object.
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*
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* Types inheriting from GarbageCollectedMixin must override a virtual method
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* of signature `void Trace(cppgc::Visitor*) const` that dispatchs all managed
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* pointers to the visitor and delegates to base classes.
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*
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* \code
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* class Mixin : public GarbageCollectedMixin {
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* public:
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* void Trace(cppgc::Visitor* visitor) const override {
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* // Dispatch using visitor->Trace(...);
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* }
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* };
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* \endcode
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*/
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class GarbageCollectedMixin : public internal::GarbageCollectedBase {
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public:
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using IsGarbageCollectedMixinTypeMarker = void;
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/**
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* This Trace method must be overriden by objects inheriting from
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* GarbageCollectedMixin.
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*/
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virtual void Trace(cppgc::Visitor*) const {}
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};
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} // namespace cppgc
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#endif // INCLUDE_CPPGC_GARBAGE_COLLECTED_H_
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