Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 521 insertions, 0 deletions

diff --git a/js/src/gc/SweepingAPI.h b/js/src/gc/SweepingAPI.h
new file mode 100644
index 0000000000..c9948d1118
--- /dev/null
+++ b/js/src/gc/SweepingAPI.h
@@ -0,0 +1,521 @@
+/* -*- 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 js_SweepingAPI_h
+#define js_SweepingAPI_h
+
+#include "mozilla/LinkedList.h"
+#include "mozilla/Maybe.h"
+
+#include "jstypes.h"
+
+#include "js/GCAnnotations.h"
+#include "js/GCHashTable.h"
+#include "js/GCPolicyAPI.h"
+#include "js/RootingAPI.h"
+
+namespace js {
+namespace gc {
+
+JS_PUBLIC_API void LockStoreBuffer(JSRuntime* runtime);
+JS_PUBLIC_API void UnlockStoreBuffer(JSRuntime* runtim);
+
+class AutoLockStoreBuffer {
+  JSRuntime* runtime;
+
+ public:
+  explicit AutoLockStoreBuffer(JSRuntime* runtime) : runtime(runtime) {
+    LockStoreBuffer(runtime);
+  }
+  ~AutoLockStoreBuffer() { UnlockStoreBuffer(runtime); }
+};
+
+class WeakCacheBase;
+JS_PUBLIC_API void RegisterWeakCache(JS::Zone* zone, WeakCacheBase* cachep);
+JS_PUBLIC_API void RegisterWeakCache(JSRuntime* rt, WeakCacheBase* cachep);
+
+class WeakCacheBase : public mozilla::LinkedListElement<WeakCacheBase> {
+  WeakCacheBase() = delete;
+  explicit WeakCacheBase(const WeakCacheBase&) = delete;
+
+ public:
+  enum NeedsLock : bool { LockStoreBuffer = true, DontLockStoreBuffer = false };
+
+  explicit WeakCacheBase(JS::Zone* zone) { RegisterWeakCache(zone, this); }
+  explicit WeakCacheBase(JSRuntime* rt) { RegisterWeakCache(rt, this); }
+  WeakCacheBase(WeakCacheBase&& other) = default;
+  virtual ~WeakCacheBase() = default;
+
+  virtual size_t traceWeak(JSTracer* trc, NeedsLock needLock) = 0;
+
+  // Sweeping will be skipped if the cache is empty already.
+  virtual bool empty() = 0;
+
+  // Enable/disable read barrier during incremental sweeping and set the tracer
+  // to use.
+  virtual bool setIncrementalBarrierTracer(JSTracer* trc) {
+    // Derived classes do not support incremental barriers by default.
+    return false;
+  }
+  virtual bool needsIncrementalBarrier() const {
+    // Derived classes do not support incremental barriers by default.
+    return false;
+  }
+};
+
+}  // namespace gc
+
+// A WeakCache stores the given Sweepable container and links itself into a
+// list of such caches that are swept during each GC. A WeakCache can be
+// specific to a zone, or across a whole runtime, depending on which
+// constructor is used.
+template <typename T>
+class WeakCache : protected gc::WeakCacheBase,
+                  public js::MutableWrappedPtrOperations<T, WeakCache<T>> {
+  T cache;
+
+ public:
+  using Type = T;
+
+  template <typename... Args>
+  explicit WeakCache(Zone* zone, Args&&... args)
+      : WeakCacheBase(zone), cache(std::forward<Args>(args)...) {}
+  template <typename... Args>
+  explicit WeakCache(JSRuntime* rt, Args&&... args)
+      : WeakCacheBase(rt), cache(std::forward<Args>(args)...) {}
+
+  const T& get() const { return cache; }
+  T& get() { return cache; }
+
+  size_t traceWeak(JSTracer* trc, NeedsLock needsLock) override {
+    // Take the store buffer lock in case sweeping triggers any generational
+    // post barriers. This is not always required and WeakCache specializations
+    // may delay or skip taking the lock as appropriate.
+    mozilla::Maybe<js::gc::AutoLockStoreBuffer> lock;
+    if (needsLock) {
+      lock.emplace(trc->runtime());
+    }
+
+    JS::GCPolicy<T>::traceWeak(trc, &cache);
+    return 0;
+  }
+
+  bool empty() override { return cache.empty(); }
+} JS_HAZ_NON_GC_POINTER;
+
+// Specialize WeakCache for GCHashMap to provide a barriered map that does not
+// need to be swept immediately.
+template <typename Key, typename Value, typename HashPolicy,
+          typename AllocPolicy, typename MapEntryGCPolicy>
+class WeakCache<
+    GCHashMap<Key, Value, HashPolicy, AllocPolicy, MapEntryGCPolicy>>
+    final : protected gc::WeakCacheBase {
+  using Map = GCHashMap<Key, Value, HashPolicy, AllocPolicy, MapEntryGCPolicy>;
+  using Self = WeakCache<Map>;
+
+  Map map;
+  JSTracer* barrierTracer = nullptr;
+
+ public:
+  template <typename... Args>
+  explicit WeakCache(Zone* zone, Args&&... args)
+      : WeakCacheBase(zone), map(std::forward<Args>(args)...) {}
+  template <typename... Args>
+  explicit WeakCache(JSRuntime* rt, Args&&... args)
+      : WeakCacheBase(rt), map(std::forward<Args>(args)...) {}
+  ~WeakCache() { MOZ_ASSERT(!barrierTracer); }
+
+  bool empty() override { return map.empty(); }
+
+  size_t traceWeak(JSTracer* trc, NeedsLock needsLock) override {
+    size_t steps = map.count();
+
+    // Create an Enum and sweep the table entries.
+    mozilla::Maybe<typename Map::Enum> e;
+    e.emplace(map);
+    map.traceWeakEntries(trc, e.ref());
+
+    // Potentially take a lock while the Enum's destructor is called as this can
+    // rehash/resize the table and access the store buffer.
+    mozilla::Maybe<js::gc::AutoLockStoreBuffer> lock;
+    if (needsLock) {
+      lock.emplace(trc->runtime());
+    }
+    e.reset();
+
+    return steps;
+  }
+
+  bool setIncrementalBarrierTracer(JSTracer* trc) override {
+    MOZ_ASSERT(bool(barrierTracer) != bool(trc));
+    barrierTracer = trc;
+    return true;
+  }
+
+  bool needsIncrementalBarrier() const override { return barrierTracer; }
+
+ private:
+  using Entry = typename Map::Entry;
+
+  static bool entryNeedsSweep(JSTracer* barrierTracer, const Entry& prior) {
+    Key key(prior.key());
+    Value value(prior.value());
+    bool needsSweep = !MapEntryGCPolicy::traceWeak(barrierTracer, &key, &value);
+    MOZ_ASSERT_IF(!needsSweep,
+                  prior.key() == key);  // We shouldn't update here.
+    MOZ_ASSERT_IF(!needsSweep,
+                  prior.value() == value);  // We shouldn't update here.
+    return needsSweep;
+  }
+
+ public:
+  using Lookup = typename Map::Lookup;
+  using Ptr = typename Map::Ptr;
+  using AddPtr = typename Map::AddPtr;
+
+  // Iterator over the whole collection.
+  struct Range {
+    explicit Range(Self& self) : cache(self), range(self.map.all()) {
+      settle();
+    }
+    Range() = default;
+
+    bool empty() const { return range.empty(); }
+    const Entry& front() const { return range.front(); }
+
+    void popFront() {
+      range.popFront();
+      settle();
+    }
+
+   private:
+    Self& cache;
+    typename Map::Range range;
+
+    void settle() {
+      if (JSTracer* trc = cache.barrierTracer) {
+        while (!empty() && entryNeedsSweep(trc, front())) {
+          popFront();
+        }
+      }
+    }
+  };
+
+  struct Enum : public Map::Enum {
+    explicit Enum(Self& cache) : Map::Enum(cache.map) {
+      // This operation is not allowed while barriers are in place as we
+      // may also need to enumerate the set for sweeping.
+      MOZ_ASSERT(!cache.barrierTracer);
+    }
+  };
+
+  Ptr lookup(const Lookup& l) const {
+    Ptr ptr = map.lookup(l);
+    if (barrierTracer && ptr && entryNeedsSweep(barrierTracer, *ptr)) {
+      const_cast<Map&>(map).remove(ptr);
+      return Ptr();
+    }
+    return ptr;
+  }
+
+  AddPtr lookupForAdd(const Lookup& l) {
+    AddPtr ptr = map.lookupForAdd(l);
+    if (barrierTracer && ptr && entryNeedsSweep(barrierTracer, *ptr)) {
+      const_cast<Map&>(map).remove(ptr);
+      return map.lookupForAdd(l);
+    }
+    return ptr;
+  }
+
+  Range all() const { return Range(*const_cast<Self*>(this)); }
+
+  bool empty() const {
+    // This operation is not currently allowed while barriers are in place
+    // as it would require iterating the map and the caller expects a
+    // constant time operation.
+    MOZ_ASSERT(!barrierTracer);
+    return map.empty();
+  }
+
+  uint32_t count() const {
+    // This operation is not currently allowed while barriers are in place
+    // as it would require iterating the set and the caller expects a
+    // constant time operation.
+    MOZ_ASSERT(!barrierTracer);
+    return map.count();
+  }
+
+  size_t capacity() const { return map.capacity(); }
+
+  bool has(const Lookup& l) const { return lookup(l).found(); }
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return map.sizeOfExcludingThis(mallocSizeOf);
+  }
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return mallocSizeOf(this) + map.shallowSizeOfExcludingThis(mallocSizeOf);
+  }
+
+  void clear() {
+    // This operation is not currently allowed while barriers are in place
+    // since it doesn't make sense to clear a cache while it is being swept.
+    MOZ_ASSERT(!barrierTracer);
+    map.clear();
+  }
+
+  void clearAndCompact() {
+    // This operation is not currently allowed while barriers are in place
+    // since it doesn't make sense to clear a cache while it is being swept.
+    MOZ_ASSERT(!barrierTracer);
+    map.clearAndCompact();
+  }
+
+  void remove(Ptr p) {
+    // This currently supports removing entries during incremental
+    // sweeping. If we allow these tables to be swept incrementally this may
+    // no longer be possible.
+    map.remove(p);
+  }
+
+  void remove(const Lookup& l) {
+    Ptr p = lookup(l);
+    if (p) {
+      remove(p);
+    }
+  }
+
+  template <typename KeyInput, typename ValueInput>
+  bool add(AddPtr& p, KeyInput&& k, ValueInput&& v) {
+    return map.add(p, std::forward<KeyInput>(k), std::forward<ValueInput>(v));
+  }
+
+  template <typename KeyInput, typename ValueInput>
+  bool relookupOrAdd(AddPtr& p, KeyInput&& k, ValueInput&& v) {
+    return map.relookupOrAdd(p, std::forward<KeyInput>(k),
+                             std::forward<ValueInput>(v));
+  }
+
+  template <typename KeyInput, typename ValueInput>
+  bool put(KeyInput&& k, ValueInput&& v) {
+    return map.put(std::forward<KeyInput>(k), std::forward<ValueInput>(v));
+  }
+
+  template <typename KeyInput, typename ValueInput>
+  bool putNew(KeyInput&& k, ValueInput&& v) {
+    return map.putNew(std::forward<KeyInput>(k), std::forward<ValueInput>(v));
+  }
+} JS_HAZ_NON_GC_POINTER;
+
+// Specialize WeakCache for GCHashSet to provide a barriered set that does not
+// need to be swept immediately.
+template <typename T, typename HashPolicy, typename AllocPolicy>
+class WeakCache<GCHashSet<T, HashPolicy, AllocPolicy>> final
+    : protected gc::WeakCacheBase {
+  using Set = GCHashSet<T, HashPolicy, AllocPolicy>;
+  using Self = WeakCache<Set>;
+
+  Set set;
+  JSTracer* barrierTracer = nullptr;
+
+ public:
+  using Entry = typename Set::Entry;
+
+  template <typename... Args>
+  explicit WeakCache(Zone* zone, Args&&... args)
+      : WeakCacheBase(zone), set(std::forward<Args>(args)...) {}
+  template <typename... Args>
+  explicit WeakCache(JSRuntime* rt, Args&&... args)
+      : WeakCacheBase(rt), set(std::forward<Args>(args)...) {}
+
+  size_t traceWeak(JSTracer* trc, NeedsLock needsLock) override {
+    size_t steps = set.count();
+
+    // Create an Enum and sweep the table entries. It's not necessary to take
+    // the store buffer lock yet.
+    mozilla::Maybe<typename Set::Enum> e;
+    e.emplace(set);
+    set.traceWeakEntries(trc, e.ref());
+
+    // Destroy the Enum, potentially rehashing or resizing the table. Since this
+    // can access the store buffer, we need to take a lock for this if we're
+    // called off main thread.
+    mozilla::Maybe<js::gc::AutoLockStoreBuffer> lock;
+    if (needsLock) {
+      lock.emplace(trc->runtime());
+    }
+    e.reset();
+
+    return steps;
+  }
+
+  bool empty() override { return set.empty(); }
+
+  bool setIncrementalBarrierTracer(JSTracer* trc) override {
+    MOZ_ASSERT(bool(barrierTracer) != bool(trc));
+    barrierTracer = trc;
+    return true;
+  }
+
+  bool needsIncrementalBarrier() const override { return barrierTracer; }
+
+ private:
+  static bool entryNeedsSweep(JSTracer* barrierTracer, const Entry& prior) {
+    Entry entry(prior);
+    bool needsSweep = !JS::GCPolicy<T>::traceWeak(barrierTracer, &entry);
+    MOZ_ASSERT_IF(!needsSweep, prior == entry);  // We shouldn't update here.
+    return needsSweep;
+  }
+
+ public:
+  using Lookup = typename Set::Lookup;
+  using Ptr = typename Set::Ptr;
+  using AddPtr = typename Set::AddPtr;
+
+  // Iterator over the whole collection.
+  struct Range {
+    explicit Range(Self& self) : cache(self), range(self.set.all()) {
+      settle();
+    }
+    Range() = default;
+
+    bool empty() const { return range.empty(); }
+    const Entry& front() const { return range.front(); }
+
+    void popFront() {
+      range.popFront();
+      settle();
+    }
+
+   private:
+    Self& cache;
+    typename Set::Range range;
+
+    void settle() {
+      if (JSTracer* trc = cache.barrierTracer) {
+        while (!empty() && entryNeedsSweep(trc, front())) {
+          popFront();
+        }
+      }
+    }
+  };
+
+  struct Enum : public Set::Enum {
+    explicit Enum(Self& cache) : Set::Enum(cache.set) {
+      // This operation is not allowed while barriers are in place as we
+      // may also need to enumerate the set for sweeping.
+      MOZ_ASSERT(!cache.barrierTracer);
+    }
+  };
+
+  Ptr lookup(const Lookup& l) const {
+    Ptr ptr = set.lookup(l);
+    if (barrierTracer && ptr && entryNeedsSweep(barrierTracer, *ptr)) {
+      const_cast<Set&>(set).remove(ptr);
+      return Ptr();
+    }
+    return ptr;
+  }
+
+  AddPtr lookupForAdd(const Lookup& l) {
+    AddPtr ptr = set.lookupForAdd(l);
+    if (barrierTracer && ptr && entryNeedsSweep(barrierTracer, *ptr)) {
+      const_cast<Set&>(set).remove(ptr);
+      return set.lookupForAdd(l);
+    }
+    return ptr;
+  }
+
+  Range all() const { return Range(*const_cast<Self*>(this)); }
+
+  bool empty() const {
+    // This operation is not currently allowed while barriers are in place
+    // as it would require iterating the set and the caller expects a
+    // constant time operation.
+    MOZ_ASSERT(!barrierTracer);
+    return set.empty();
+  }
+
+  uint32_t count() const {
+    // This operation is not currently allowed while barriers are in place
+    // as it would require iterating the set and the caller expects a
+    // constant time operation.
+    MOZ_ASSERT(!barrierTracer);
+    return set.count();
+  }
+
+  size_t capacity() const { return set.capacity(); }
+
+  bool has(const Lookup& l) const { return lookup(l).found(); }
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return set.shallowSizeOfExcludingThis(mallocSizeOf);
+  }
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return mallocSizeOf(this) + set.shallowSizeOfExcludingThis(mallocSizeOf);
+  }
+
+  void clear() {
+    // This operation is not currently allowed while barriers are in place
+    // since it doesn't make sense to clear a cache while it is being swept.
+    MOZ_ASSERT(!barrierTracer);
+    set.clear();
+  }
+
+  void clearAndCompact() {
+    // This operation is not currently allowed while barriers are in place
+    // since it doesn't make sense to clear a cache while it is being swept.
+    MOZ_ASSERT(!barrierTracer);
+    set.clearAndCompact();
+  }
+
+  void remove(Ptr p) {
+    // This currently supports removing entries during incremental
+    // sweeping. If we allow these tables to be swept incrementally this may
+    // no longer be possible.
+    set.remove(p);
+  }
+
+  void remove(const Lookup& l) {
+    Ptr p = lookup(l);
+    if (p) {
+      remove(p);
+    }
+  }
+
+  template <typename TInput>
+  void replaceKey(Ptr p, const Lookup& l, TInput&& newValue) {
+    set.replaceKey(p, l, std::forward<TInput>(newValue));
+  }
+
+  template <typename TInput>
+  bool add(AddPtr& p, TInput&& t) {
+    return set.add(p, std::forward<TInput>(t));
+  }
+
+  template <typename TInput>
+  bool relookupOrAdd(AddPtr& p, const Lookup& l, TInput&& t) {
+    return set.relookupOrAdd(p, l, std::forward<TInput>(t));
+  }
+
+  template <typename TInput>
+  bool put(TInput&& t) {
+    return set.put(std::forward<TInput>(t));
+  }
+
+  template <typename TInput>
+  bool putNew(TInput&& t) {
+    return set.putNew(std::forward<TInput>(t));
+  }
+
+  template <typename TInput>
+  bool putNew(const Lookup& l, TInput&& t) {
+    return set.putNew(l, std::forward<TInput>(t));
+  }
+} JS_HAZ_NON_GC_POINTER;
+
+}  // namespace js
+
+#endif  // js_SweepingAPI_h