Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 334 insertions, 0 deletions

diff --git a/js/src/vm/PlainObject.cpp b/js/src/vm/PlainObject.cpp
new file mode 100644
index 0000000000..e238203e27
--- /dev/null
+++ b/js/src/vm/PlainObject.cpp
@@ -0,0 +1,334 @@
+/* -*- 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 object implementation.
+ */
+
+#include "vm/PlainObject-inl.h"
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT
+
+#include "jspubtd.h"  // JSProto_Object
+
+#include "ds/IdValuePair.h"  // js::IdValuePair
+#include "gc/AllocKind.h"    // js::gc::AllocKind
+#include "vm/JSContext.h"    // JSContext
+#include "vm/JSFunction.h"   // JSFunction
+#include "vm/JSObject.h"     // JSObject, js::GetPrototypeFromConstructor
+#include "vm/TaggedProto.h"  // js::TaggedProto
+
+#include "vm/JSFunction-inl.h"
+#include "vm/JSObject-inl.h"  // js::NewObjectWithGroup, js::NewObjectGCKind
+
+using namespace js;
+
+using JS::Handle;
+using JS::Rooted;
+
+static MOZ_ALWAYS_INLINE SharedShape* GetPlainObjectShapeWithProto(
+    JSContext* cx, JSObject* proto, gc::AllocKind kind) {
+  MOZ_ASSERT(JSCLASS_RESERVED_SLOTS(&PlainObject::class_) == 0,
+             "all slots can be used for properties");
+  uint32_t nfixed = GetGCKindSlots(kind);
+  return SharedShape::getInitialShape(cx, &PlainObject::class_, cx->realm(),
+                                      TaggedProto(proto), nfixed);
+}
+
+SharedShape* js::ThisShapeForFunction(JSContext* cx, Handle<JSFunction*> callee,
+                                      Handle<JSObject*> newTarget) {
+  MOZ_ASSERT(cx->realm() == callee->realm());
+  MOZ_ASSERT(!callee->constructorNeedsUninitializedThis());
+
+  Rooted<JSObject*> proto(cx);
+  if (!GetPrototypeFromConstructor(cx, newTarget, JSProto_Object, &proto)) {
+    return nullptr;
+  }
+
+  js::gc::AllocKind allocKind = NewObjectGCKind();
+  if (!JSFunction::getAllocKindForThis(cx, callee, allocKind)) {
+    return nullptr;
+  }
+
+  SharedShape* res;
+  if (proto && proto != cx->global()->maybeGetPrototype(JSProto_Object)) {
+    res = GetPlainObjectShapeWithProto(cx, proto, allocKind);
+  } else {
+    res = GlobalObject::getPlainObjectShapeWithDefaultProto(cx, allocKind);
+  }
+
+  MOZ_ASSERT_IF(res, res->realm() == callee->realm());
+
+  return res;
+}
+
+#ifdef DEBUG
+void PlainObject::assertHasNoNonWritableOrAccessorPropExclProto() const {
+  // Check the most recent MaxCount properties to not slow down debug builds too
+  // much.
+  static constexpr size_t MaxCount = 8;
+
+  size_t count = 0;
+  PropertyName* protoName = runtimeFromMainThread()->commonNames->proto;
+
+  for (ShapePropertyIter<NoGC> iter(shape()); !iter.done(); iter++) {
+    // __proto__ is always allowed.
+    if (iter->key().isAtom(protoName)) {
+      continue;
+    }
+
+    MOZ_ASSERT(iter->isDataProperty());
+    MOZ_ASSERT(iter->writable());
+
+    count++;
+    if (count > MaxCount) {
+      return;
+    }
+  }
+}
+#endif
+
+// static
+PlainObject* PlainObject::createWithTemplateFromDifferentRealm(
+    JSContext* cx, Handle<PlainObject*> templateObject) {
+  MOZ_ASSERT(cx->realm() != templateObject->realm(),
+             "Use createWithTemplate() for same-realm objects");
+
+  // Currently only implemented for null-proto.
+  MOZ_ASSERT(templateObject->staticPrototype() == nullptr);
+
+  // The object mustn't be in dictionary mode.
+  MOZ_ASSERT(!templateObject->shape()->isDictionary());
+
+  TaggedProto proto = TaggedProto(nullptr);
+  SharedShape* templateShape = templateObject->sharedShape();
+  Rooted<SharedPropMap*> map(cx, templateShape->propMap());
+
+  Rooted<SharedShape*> shape(
+      cx, SharedShape::getInitialOrPropMapShape(
+              cx, &PlainObject::class_, cx->realm(), proto,
+              templateShape->numFixedSlots(), map,
+              templateShape->propMapLength(), templateShape->objectFlags()));
+  if (!shape) {
+    return nullptr;
+  }
+  return createWithShape(cx, shape);
+}
+
+// static
+SharedShape* GlobalObject::createPlainObjectShapeWithDefaultProto(
+    JSContext* cx, gc::AllocKind kind) {
+  PlainObjectSlotsKind slotsKind = PlainObjectSlotsKindFromAllocKind(kind);
+  HeapPtr<SharedShape*>& shapeRef =
+      cx->global()->data().plainObjectShapesWithDefaultProto[slotsKind];
+  MOZ_ASSERT(!shapeRef);
+
+  JSObject* proto = &cx->global()->getObjectPrototype();
+  SharedShape* shape = GetPlainObjectShapeWithProto(cx, proto, kind);
+  if (!shape) {
+    return nullptr;
+  }
+
+  shapeRef.init(shape);
+  return shape;
+}
+
+PlainObject* js::NewPlainObject(JSContext* cx, NewObjectKind newKind) {
+  constexpr gc::AllocKind allocKind = gc::AllocKind::OBJECT0;
+  MOZ_ASSERT(gc::GetGCObjectKind(&PlainObject::class_) == allocKind);
+
+  Rooted<SharedShape*> shape(
+      cx, GlobalObject::getPlainObjectShapeWithDefaultProto(cx, allocKind));
+  if (!shape) {
+    return nullptr;
+  }
+
+  return PlainObject::createWithShape(cx, shape, allocKind, newKind);
+}
+
+PlainObject* js::NewPlainObjectWithAllocKind(JSContext* cx,
+                                             gc::AllocKind allocKind,
+                                             NewObjectKind newKind) {
+  Rooted<SharedShape*> shape(
+      cx, GlobalObject::getPlainObjectShapeWithDefaultProto(cx, allocKind));
+  if (!shape) {
+    return nullptr;
+  }
+
+  return PlainObject::createWithShape(cx, shape, allocKind, newKind);
+}
+
+PlainObject* js::NewPlainObjectWithProto(JSContext* cx, HandleObject proto,
+                                         NewObjectKind newKind) {
+  // Use a faster path if |proto| is %Object.prototype% (the common case).
+  if (proto && proto == cx->global()->maybeGetPrototype(JSProto_Object)) {
+    return NewPlainObject(cx, newKind);
+  }
+
+  constexpr gc::AllocKind allocKind = gc::AllocKind::OBJECT0;
+  MOZ_ASSERT(gc::GetGCObjectKind(&PlainObject::class_) == allocKind);
+
+  Rooted<SharedShape*> shape(
+      cx, GetPlainObjectShapeWithProto(cx, proto, allocKind));
+  if (!shape) {
+    return nullptr;
+  }
+
+  return PlainObject::createWithShape(cx, shape, allocKind, newKind);
+}
+
+PlainObject* js::NewPlainObjectWithProtoAndAllocKind(JSContext* cx,
+                                                     HandleObject proto,
+                                                     gc::AllocKind allocKind,
+                                                     NewObjectKind newKind) {
+  // Use a faster path if |proto| is %Object.prototype% (the common case).
+  if (proto && proto == cx->global()->maybeGetPrototype(JSProto_Object)) {
+    return NewPlainObjectWithAllocKind(cx, allocKind, newKind);
+  }
+
+  Rooted<SharedShape*> shape(
+      cx, GetPlainObjectShapeWithProto(cx, proto, allocKind));
+  if (!shape) {
+    return nullptr;
+  }
+
+  return PlainObject::createWithShape(cx, shape, allocKind, newKind);
+}
+
+void js::NewPlainObjectWithPropsCache::add(SharedShape* shape) {
+  MOZ_ASSERT(shape);
+  MOZ_ASSERT(shape->slotSpan() > 0);
+  for (size_t i = NumEntries - 1; i > 0; i--) {
+    entries_[i] = entries_[i - 1];
+  }
+  entries_[0] = shape;
+}
+
+static bool ShapeMatches(IdValuePair* properties, size_t nproperties,
+                         SharedShape* shape) {
+  if (shape->slotSpan() != nproperties) {
+    return false;
+  }
+  SharedShapePropertyIter<NoGC> iter(shape);
+  for (size_t i = nproperties; i > 0; i--) {
+    MOZ_ASSERT(iter->isDataProperty());
+    MOZ_ASSERT(iter->flags() == PropertyFlags::defaultDataPropFlags);
+    if (properties[i - 1].id != iter->key()) {
+      return false;
+    }
+    iter++;
+  }
+  MOZ_ASSERT(iter.done());
+  return true;
+}
+
+SharedShape* js::NewPlainObjectWithPropsCache::lookup(
+    IdValuePair* properties, size_t nproperties) const {
+  for (size_t i = 0; i < NumEntries; i++) {
+    SharedShape* shape = entries_[i];
+    if (shape && ShapeMatches(properties, nproperties, shape)) {
+      return shape;
+    }
+  }
+  return nullptr;
+}
+
+enum class KeysKind { UniqueNames, Unknown };
+
+template <KeysKind Kind>
+static PlainObject* NewPlainObjectWithProperties(JSContext* cx,
+                                                 IdValuePair* properties,
+                                                 size_t nproperties) {
+  auto& cache = cx->realm()->newPlainObjectWithPropsCache;
+
+  // If we recently created an object with these properties, we can use that
+  // Shape directly.
+  if (SharedShape* shape = cache.lookup(properties, nproperties)) {
+    Rooted<SharedShape*> shapeRoot(cx, shape);
+    PlainObject* obj = PlainObject::createWithShape(cx, shapeRoot);
+    if (!obj) {
+      return nullptr;
+    }
+    MOZ_ASSERT(obj->slotSpan() == nproperties);
+    for (size_t i = 0; i < nproperties; i++) {
+      obj->initSlot(i, properties[i].value);
+    }
+    return obj;
+  }
+
+  gc::AllocKind allocKind = gc::GetGCObjectKind(nproperties);
+  Rooted<PlainObject*> obj(cx, NewPlainObjectWithAllocKind(cx, allocKind));
+  if (!obj) {
+    return nullptr;
+  }
+
+  if (nproperties == 0) {
+    return obj;
+  }
+
+  Rooted<PropertyKey> key(cx);
+  Rooted<Value> value(cx);
+  bool canCache = true;
+
+  for (size_t i = 0; i < nproperties; i++) {
+    key = properties[i].id;
+    value = properties[i].value;
+
+    // Integer keys may need to be stored in dense elements. This is uncommon so
+    // just fall back to NativeDefineDataProperty.
+    if constexpr (Kind == KeysKind::Unknown) {
+      if (MOZ_UNLIKELY(key.isInt())) {
+        canCache = false;
+        if (!NativeDefineDataProperty(cx, obj, key, value, JSPROP_ENUMERATE)) {
+          return nullptr;
+        }
+        continue;
+      }
+    }
+
+    MOZ_ASSERT(key.isAtom() || key.isSymbol());
+
+    // Check for duplicate keys. In this case we must overwrite the earlier
+    // property value.
+    if constexpr (Kind == KeysKind::UniqueNames) {
+      MOZ_ASSERT(!obj->containsPure(key));
+    } else {
+      mozilla::Maybe<PropertyInfo> prop = obj->lookup(cx, key);
+      if (MOZ_UNLIKELY(prop)) {
+        canCache = false;
+        MOZ_ASSERT(prop->isDataProperty());
+        obj->setSlot(prop->slot(), value);
+        continue;
+      }
+    }
+
+    if (!AddDataPropertyToPlainObject(cx, obj, key, value)) {
+      return nullptr;
+    }
+  }
+
+  if (canCache && !obj->inDictionaryMode()) {
+    MOZ_ASSERT(obj->getDenseInitializedLength() == 0);
+    MOZ_ASSERT(obj->slotSpan() == nproperties);
+    cache.add(obj->sharedShape());
+  }
+
+  return obj;
+}
+
+PlainObject* js::NewPlainObjectWithUniqueNames(JSContext* cx,
+                                               IdValuePair* properties,
+                                               size_t nproperties) {
+  return NewPlainObjectWithProperties<KeysKind::UniqueNames>(cx, properties,
+                                                             nproperties);
+}
+
+PlainObject* js::NewPlainObjectWithMaybeDuplicateKeys(JSContext* cx,
+                                                      IdValuePair* properties,
+                                                      size_t nproperties) {
+  return NewPlainObjectWithProperties<KeysKind::Unknown>(cx, properties,
+                                                         nproperties);
+}