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-rw-r--r--js/src/gc/Policy.h101
1 files changed, 101 insertions, 0 deletions
diff --git a/js/src/gc/Policy.h b/js/src/gc/Policy.h
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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/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