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9297562 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 | // 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.
#ifndef INCLUDE_CPPGC_INTERNAL_GC_INFO_H_
#define INCLUDE_CPPGC_INTERNAL_GC_INFO_H_
#include <atomic>
#include <cstdint>
#include <type_traits>
#include "cppgc/internal/finalizer-trait.h"
#include "cppgc/internal/logging.h"
#include "cppgc/internal/name-trait.h"
#include "cppgc/trace-trait.h"
#include "v8config.h" // NOLINT(build/include_directory)
namespace cppgc {
namespace internal {
using GCInfoIndex = uint16_t;
struct V8_EXPORT EnsureGCInfoIndexTrait final {
// Acquires a new GC info object and updates `registered_index` with the index
// that identifies that new info accordingly.
template <typename T>
V8_INLINE static void EnsureIndex(
std::atomic<GCInfoIndex>& registered_index) {
EnsureGCInfoIndexTraitDispatch<T>{}(registered_index);
}
private:
template <typename T, bool = std::is_polymorphic<T>::value,
bool = FinalizerTrait<T>::HasFinalizer(),
bool = NameTrait<T>::HasNonHiddenName()>
struct EnsureGCInfoIndexTraitDispatch;
static void V8_PRESERVE_MOST
EnsureGCInfoIndexPolymorphic(std::atomic<GCInfoIndex>&, TraceCallback,
FinalizationCallback, NameCallback);
static void V8_PRESERVE_MOST EnsureGCInfoIndexPolymorphic(
std::atomic<GCInfoIndex>&, TraceCallback, FinalizationCallback);
static void V8_PRESERVE_MOST EnsureGCInfoIndexPolymorphic(
std::atomic<GCInfoIndex>&, TraceCallback, NameCallback);
static void V8_PRESERVE_MOST
EnsureGCInfoIndexPolymorphic(std::atomic<GCInfoIndex>&, TraceCallback);
static void V8_PRESERVE_MOST
EnsureGCInfoIndexNonPolymorphic(std::atomic<GCInfoIndex>&, TraceCallback,
FinalizationCallback, NameCallback);
static void V8_PRESERVE_MOST EnsureGCInfoIndexNonPolymorphic(
std::atomic<GCInfoIndex>&, TraceCallback, FinalizationCallback);
static void V8_PRESERVE_MOST EnsureGCInfoIndexNonPolymorphic(
std::atomic<GCInfoIndex>&, TraceCallback, NameCallback);
static void V8_PRESERVE_MOST
EnsureGCInfoIndexNonPolymorphic(std::atomic<GCInfoIndex>&, TraceCallback);
};
#define DISPATCH(is_polymorphic, has_finalizer, has_non_hidden_name, function) \
template <typename T> \
struct EnsureGCInfoIndexTrait::EnsureGCInfoIndexTraitDispatch< \
T, is_polymorphic, has_finalizer, has_non_hidden_name> { \
V8_INLINE void operator()(std::atomic<GCInfoIndex>& registered_index) { \
function; \
} \
};
// --------------------------------------------------------------------- //
// DISPATCH(is_polymorphic, has_finalizer, has_non_hidden_name, function)
// --------------------------------------------------------------------- //
DISPATCH(true, true, true, //
EnsureGCInfoIndexPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
FinalizerTrait<T>::kCallback, //
NameTrait<T>::GetName)) //
DISPATCH(true, true, false, //
EnsureGCInfoIndexPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
FinalizerTrait<T>::kCallback)) //
DISPATCH(true, false, true, //
EnsureGCInfoIndexPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
NameTrait<T>::GetName)) //
DISPATCH(true, false, false, //
EnsureGCInfoIndexPolymorphic(registered_index, //
TraceTrait<T>::Trace)) //
DISPATCH(false, true, true, //
EnsureGCInfoIndexNonPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
FinalizerTrait<T>::kCallback, //
NameTrait<T>::GetName)) //
DISPATCH(false, true, false, //
EnsureGCInfoIndexNonPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
FinalizerTrait<T>::kCallback)) //
DISPATCH(false, false, true, //
EnsureGCInfoIndexNonPolymorphic(registered_index, //
TraceTrait<T>::Trace, //
NameTrait<T>::GetName)) //
DISPATCH(false, false, false, //
EnsureGCInfoIndexNonPolymorphic(registered_index, //
TraceTrait<T>::Trace)) //
#undef DISPATCH
// Fold types based on finalizer behavior. Note that finalizer characteristics
// align with trace behavior, i.e., destructors are virtual when trace methods
// are and vice versa.
template <typename T, typename ParentMostGarbageCollectedType>
struct GCInfoFolding {
static constexpr bool kHasVirtualDestructorAtBase =
std::has_virtual_destructor<ParentMostGarbageCollectedType>::value;
static constexpr bool kBothTypesAreTriviallyDestructible =
std::is_trivially_destructible<ParentMostGarbageCollectedType>::value &&
std::is_trivially_destructible<T>::value;
static constexpr bool kHasCustomFinalizerDispatchAtBase =
internal::HasFinalizeGarbageCollectedObject<
ParentMostGarbageCollectedType>::value;
#ifdef CPPGC_SUPPORTS_OBJECT_NAMES
static constexpr bool kWantsDetailedObjectNames = true;
#else // !CPPGC_SUPPORTS_OBJECT_NAMES
static constexpr bool kWantsDetailedObjectNames = false;
#endif // !CPPGC_SUPPORTS_OBJECT_NAMES
// Folding would regresses name resolution when deriving names from C++
// class names as it would just folds a name to the base class name.
using ResultType = std::conditional_t<(kHasVirtualDestructorAtBase ||
kBothTypesAreTriviallyDestructible ||
kHasCustomFinalizerDispatchAtBase) &&
!kWantsDetailedObjectNames,
ParentMostGarbageCollectedType, T>;
};
// Trait determines how the garbage collector treats objects wrt. to traversing,
// finalization, and naming.
template <typename T>
struct GCInfoTrait final {
V8_INLINE static GCInfoIndex Index() {
static_assert(sizeof(T), "T must be fully defined");
static std::atomic<GCInfoIndex>
registered_index; // Uses zero initialization.
GCInfoIndex index = registered_index.load(std::memory_order_acquire);
if (V8_UNLIKELY(!index)) {
EnsureGCInfoIndexTrait::EnsureIndex<T>(registered_index);
// Slow path call uses V8_PRESERVE_MOST which does not support return
// values (also preserves RAX). Avoid out parameter by just reloading the
// value here which at this point is guaranteed to be set.
index = registered_index.load(std::memory_order_acquire);
CPPGC_DCHECK(index != 0);
}
return index;
}
};
} // namespace internal
} // namespace cppgc
#endif // INCLUDE_CPPGC_INTERNAL_GC_INFO_H_
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