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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/. */
/* JS Garbage Collector. */
#ifndef gc_Policy_h
#define gc_Policy_h
#include <type_traits>
#include "gc/Barrier.h"
#include "gc/Marking.h"
#include "js/GCPolicyAPI.h"
namespace js {
// Define the GCPolicy for all internal pointers.
template <typename T>
struct InternalGCPointerPolicy : public JS::GCPointerPolicy<T> {
using Type = std::remove_pointer_t<T>;
#define IS_BASE_OF_OR(_1, BaseType, _2, _3) std::is_base_of_v<BaseType, Type> ||
static_assert(
JS_FOR_EACH_TRACEKIND(IS_BASE_OF_OR) false,
"InternalGCPointerPolicy must only be used for GC thing pointers");
#undef IS_BASE_OF_OR
static void preBarrier(T v) {
if (v) {
Type::writeBarrierPre(v);
}
}
static void postBarrier(T* vp, T prev, T next) {
if (*vp) {
Type::writeBarrierPost(vp, prev, next);
}
}
static void readBarrier(T v) {
if (v) {
Type::readBarrier(v);
}
}
static void trace(JSTracer* trc, T* vp, const char* name) {
// It's not safe to trace unbarriered pointers except as part of root
// marking. If you get an assertion here you probably need to add a barrier,
// e.g. HeapPtr<T>.
TraceNullableRoot(trc, vp, name);
}
};
} // namespace js
namespace JS {
// Internally, all pointer types are treated as pointers to GC things by
// default.
template <typename T>
struct GCPolicy<T*> : public js::InternalGCPointerPolicy<T*> {};
template <typename T>
struct GCPolicy<T* const> : public js::InternalGCPointerPolicy<T* const> {};
template <typename T>
struct GCPolicy<js::HeapPtr<T>> {
static void trace(JSTracer* trc, js::HeapPtr<T>* thingp, const char* name) {
js::TraceNullableEdge(trc, thingp, name);
}
static bool needsSweep(js::HeapPtr<T>* thingp) {
return js::gc::IsAboutToBeFinalized(thingp);
}
static bool traceWeak(JSTracer* trc, js::HeapPtr<T>* thingp) {
return js::TraceWeakEdge(trc, thingp, "traceWeak");
}
};
template <typename T>
struct GCPolicy<js::PreBarriered<T>> {
static void trace(JSTracer* trc, js::PreBarriered<T>* thingp,
const char* name) {
js::TraceNullableEdge(trc, thingp, name);
}
static bool needsSweep(js::PreBarriered<T>* thingp) {
return js::gc::IsAboutToBeFinalized(thingp);
}
};
template <typename T>
struct GCPolicy<js::WeakHeapPtr<T>> {
static void trace(JSTracer* trc, js::WeakHeapPtr<T>* thingp,
const char* name) {
js::TraceEdge(trc, thingp, name);
}
static bool needsSweep(js::WeakHeapPtr<T>* thingp) {
return js::gc::IsAboutToBeFinalized(thingp);
}
static bool traceWeak(JSTracer* trc, js::WeakHeapPtr<T>* thingp) {
return js::TraceWeakEdge(trc, thingp, "traceWeak");
}
};
template <>
struct GCPolicy<JS::GCCellPtr> {
static void trace(JSTracer* trc, JS::GCCellPtr* thingp, const char* name) {
// It's not safe to trace unbarriered pointers except as part of root
// marking.
js::TraceGCCellPtrRoot(trc, thingp, name);
}
};
} // namespace JS
#endif // gc_Policy_h