Source code

Revision control

Other Tools

/* -*- 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 "mozilla/Maybe.h"
#include <type_traits>
#include "gc/RelocationOverlay.h"
#include "vm/BigIntType.h"
#include "vm/RegExpShared.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) { return JS::ObjectOrNullValue(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::fromNonIntAtom(str);
}
static jsid wrap(JS::Symbol* sym) { return SYMBOL_TO_JSID(sym); }
static jsid empty() { return JSID_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>, "T must derive from Cell");
static_assert(!std::is_same_v<Cell, T> && !std::is_same_v<TenuredCell, T>,
"T must not be Cell or TenuredCell");
static const bool value =
std::is_base_of_v<JSObject, T> || std::is_base_of_v<Shape, T> ||
std::is_base_of_v<BaseShape, T> || std::is_base_of_v<JSString, T> ||
std::is_base_of_v<JS::BigInt, T> ||
std::is_base_of_v<js::BaseScript, T> || std::is_base_of_v<js::Scope, T> ||
std::is_base_of_v<js::RegExpShared, T> ||
std::is_base_of_v<js::ObjectGroup, T>;
};
template <typename T>
inline bool IsForwarded(const T* t) {
if (!MightBeForwarded<T>::value) {
MOZ_ASSERT(!t->isForwarded());
return false;
}
return t->isForwarded();
}
inline bool IsForwarded(const JS::Value& value) {
auto isForwarded = [](auto t) { return IsForwarded(t); };
return MapGCThingTyped(value, isForwarded).valueOr(false);
}
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());
}
inline Value Forwarded(const JS::Value& value) {
auto forward = [](auto t) { return TaggedPtr<Value>::wrap(Forwarded(t)); };
return MapGCThingTyped(value, forward).valueOr(value);
}
template <typename T>
inline T MaybeForwarded(T t) {
if (IsForwarded(t)) {
t = Forwarded(t);
}
return t;
}
inline const JSClass* MaybeForwardedObjectClass(const JSObject* obj) {
return MaybeForwarded(obj->groupRaw())->clasp();
}
template <typename T>
inline bool MaybeForwardedObjectIs(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);
MOZ_ASSERT((ptr & RESERVED_MASK) == 0);
header_ = ptr | FORWARD_BIT;
}
/* 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);
}
#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());
}
inline void CheckValueAfterMovingGC(const JS::Value& value) {
ApplyGCThingTyped(value, [](auto t) { CheckGCThingAfterMovingGC(t); });
}
#endif // JSGC_HASH_TABLE_CHECKS
} /* namespace gc */
} /* namespace js */
#endif // gc_Marking_inl_h