/* -*- 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/Tracer.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 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 traceWeak(JSTracer* trc, js::HeapPtr<T>* thingp) { return js::TraceWeakEdge(trc, thingp, "HeapPtr"); } }; 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); } }; 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 traceWeak(JSTracer* trc, js::WeakHeapPtr<T>* thingp) { return js::TraceWeakEdge(trc, thingp, "traceWeak"); } }; template <typename T> struct GCPolicy<js::UnsafeBarePtr<T>> { static bool traceWeak(JSTracer* trc, js::UnsafeBarePtr<T>* vp) { if (*vp) { return js::TraceManuallyBarrieredWeakEdge(trc, vp->unbarrieredAddress(), "UnsafeBarePtr"); } return true; } }; 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