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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef gc_Marking_inl_h
#define gc_Marking_inl_h
#include "gc/Marking.h"
#include <type_traits>
#include "gc/RelocationOverlay.h"
#include "js/Id.h"
#include "js/Value.h"
#include "vm/StringType.h"
#include "vm/TaggedProto.h"
#include "gc/Nursery-inl.h"
namespace js {
namespace gc {
// An abstraction to re-wrap any kind of typed pointer back to the tagged
// pointer it came from with |TaggedPtr<TargetType>::wrap(sourcePtr)|.
template <typename T>
struct TaggedPtr {};
template <>
struct TaggedPtr<JS::Value> {
static JS::Value wrap(JSObject* obj) {
if (!obj) {
return JS::NullValue();
}
#ifdef ENABLE_RECORD_TUPLE
if (MaybeForwardedIsExtendedPrimitive(*obj)) {
return JS::ExtendedPrimitiveValue(*obj);
}
#endif
return JS::ObjectValue(*obj);
}
static JS::Value wrap(JSString* str) { return JS::StringValue(str); }
static JS::Value wrap(JS::Symbol* sym) { return JS::SymbolValue(sym); }
static JS::Value wrap(JS::BigInt* bi) { return JS::BigIntValue(bi); }
template <typename T>
static JS::Value wrap(T* priv) {
static_assert(std::is_base_of_v<Cell, T>,
"Type must be a GC thing derived from js::gc::Cell");
return JS::PrivateGCThingValue(priv);
}
static JS::Value empty() { return JS::UndefinedValue(); }
};
template <>
struct TaggedPtr<jsid> {
static jsid wrap(JSString* str) { return JS::PropertyKey::NonIntAtom(str); }
static jsid wrap(JS::Symbol* sym) { return PropertyKey::Symbol(sym); }
static jsid empty() { return JS::PropertyKey::Void(); }
};
template <>
struct TaggedPtr<TaggedProto> {
static TaggedProto wrap(JSObject* obj) { return TaggedProto(obj); }
static TaggedProto empty() { return TaggedProto(); }
};
template <typename T>
struct MightBeForwarded {
static_assert(std::is_base_of_v<Cell, T>);
static_assert(!std::is_same_v<Cell, T> && !std::is_same_v<TenuredCell, T>);
#define CAN_FORWARD_KIND_OR(_1, _2, Type, _3, _4, _5, canCompact) \
std::is_base_of_v<Type, T> ? canCompact:
// FOR_EACH_ALLOCKIND doesn't cover every possible type: make sure
// to default to `true` for unknown types.
static constexpr bool value = FOR_EACH_ALLOCKIND(CAN_FORWARD_KIND_OR) true;
#undef CAN_FORWARD_KIND_OR
};
template <typename T>
inline bool IsForwarded(const T* t) {
if (!MightBeForwarded<T>::value) {
MOZ_ASSERT(!t->isForwarded());
return false;
}
return t->isForwarded();
}
template <typename T>
inline T* Forwarded(const T* t) {
const RelocationOverlay* overlay = RelocationOverlay::fromCell(t);
MOZ_ASSERT(overlay->isForwarded());
return reinterpret_cast<T*>(overlay->forwardingAddress());
}
template <typename T>
inline T MaybeForwarded(T t) {
if (IsForwarded(t)) {
t = Forwarded(t);
}
MOZ_ASSERT(!IsForwarded(t));
return t;
}
inline const JSClass* MaybeForwardedObjectClass(const JSObject* obj) {
Shape* shape = MaybeForwarded(obj->shapeMaybeForwarded());
BaseShape* baseShape = MaybeForwarded(shape->base());
return baseShape->clasp();
}
template <typename T>
inline bool MaybeForwardedObjectIs(const JSObject* obj) {
MOZ_ASSERT(!obj->isForwarded());
return MaybeForwardedObjectClass(obj) == &T::class_;
}
template <typename T>
inline T& MaybeForwardedObjectAs(JSObject* obj) {
MOZ_ASSERT(MaybeForwardedObjectIs<T>(obj));
return *static_cast<T*>(obj);
}
inline RelocationOverlay::RelocationOverlay(Cell* dst) {
MOZ_ASSERT(dst->flags() == 0);
uintptr_t ptr = uintptr_t(dst);
header_.setForwardingAddress(ptr);
}
/* static */
inline RelocationOverlay* RelocationOverlay::forwardCell(Cell* src, Cell* dst) {
MOZ_ASSERT(!src->isForwarded());
MOZ_ASSERT(!dst->isForwarded());
return new (src) RelocationOverlay(dst);
}
inline bool IsAboutToBeFinalizedDuringMinorSweep(Cell** cellp) {
MOZ_ASSERT(JS::RuntimeHeapIsMinorCollecting());
if ((*cellp)->isTenured()) {
return false;
}
return !Nursery::getForwardedPointer(cellp);
}
// Special case pre-write barrier for strings used during rope flattening. This
// avoids eager marking of ropes which does not immediately mark the cells if we
// hit OOM. This does not traverse ropes and is instead called on every node in
// a rope during flattening.
inline void PreWriteBarrierDuringFlattening(JSString* str) {
MOZ_ASSERT(str);
MOZ_ASSERT(!JS::RuntimeHeapIsMajorCollecting());
if (IsInsideNursery(str)) {
return;
}
auto* cell = reinterpret_cast<TenuredCell*>(str);
JS::shadow::Zone* zone = cell->shadowZoneFromAnyThread();
if (!zone->needsIncrementalBarrier()) {
return;
}
MOZ_ASSERT(!str->isPermanentAndMayBeShared());
MOZ_ASSERT(CurrentThreadCanAccessRuntime(zone->runtimeFromAnyThread()));
PerformIncrementalBarrierDuringFlattening(str);
}
#ifdef JSGC_HASH_TABLE_CHECKS
template <typename T>
inline bool IsGCThingValidAfterMovingGC(T* t) {
return !IsInsideNursery(t) && !t->isForwarded();
}
template <typename T>
inline void CheckGCThingAfterMovingGC(T* t) {
if (t) {
MOZ_RELEASE_ASSERT(IsGCThingValidAfterMovingGC(t));
}
}
template <typename T>
inline void CheckGCThingAfterMovingGC(const WeakHeapPtr<T*>& t) {
CheckGCThingAfterMovingGC(t.unbarrieredGet());
}
#endif // JSGC_HASH_TABLE_CHECKS
} /* namespace gc */
} /* namespace js */
#endif // gc_Marking_inl_h
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