[key-accumulator] Starting to reimplement the key-accumulator

src/key-accumulator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/key-accumulator.h"
 
 #include "src/elements.h"
 #include "src/factory.h"
 #include "src/isolate-inl.h"
 #include "src/objects-inl.h"
 #include "src/property-descriptor.h"
-
+#include "src/prototype.h"
 
 namespace v8 {
 namespace internal {
 
-
 KeyAccumulator::~KeyAccumulator() {
   for (size_t i = 0; i < elements_.size(); i++) {
     delete elements_[i];
   }
 }
 
-
 Handle<FixedArray> KeyAccumulator::GetKeys(GetKeysConversion convert) {
   if (length_ == 0) {
     return isolate_->factory()->empty_fixed_array();
   }
   // Make sure we have all the lengths collected.
   NextPrototype();
 
   if (type_ == OWN_ONLY && !ownProxyKeys_.is_null()) {
     return ownProxyKeys_;
   }
@@ skipping 57 matching lines @@
 bool AccumulatorHasKey(std::vector<uint32_t>* sub_elements, uint32_t key) {
   return std::binary_search(sub_elements->begin(), sub_elements->end(), key);
 }
 
 }  // namespace
 
 bool KeyAccumulator::AddKey(Object* key, AddKeyConversion convert) {
   return AddKey(handle(key, isolate_), convert);
 }
 
-
 bool KeyAccumulator::AddKey(Handle<Object> key, AddKeyConversion convert) {
   if (key->IsSymbol()) {
     if (filter_ & SKIP_SYMBOLS) return false;
     if (Handle<Symbol>::cast(key)->is_private()) return false;
     return AddSymbolKey(key);
   }
   if (filter_ & SKIP_STRINGS) return false;
   // Make sure we do not add keys to a proxy-level (see AddKeysFromProxy).
   DCHECK_LE(0, level_string_length_);
   // In some cases (e.g. proxies) we might get in String-converted ints which
@@ skipping 16 matching lines @@
           return false;
         }
         length_ = prev_length;
         level_string_length_ = prev_proto;
       }
     }
   }
   return AddStringKey(key, convert);
 }
 
-
 bool KeyAccumulator::AddKey(uint32_t key) { return AddIntegerKey(key); }
 
-
 bool KeyAccumulator::AddIntegerKey(uint32_t key) {
   // Make sure we do not add keys to a proxy-level (see AddKeysFromProxy).
   // We mark proxy-levels with a negative length
   DCHECK_LE(0, level_string_length_);
   // Binary search over all but the last level. The last one might not be
   // sorted yet.
   for (size_t i = 1; i < elements_.size(); i++) {
     if (AccumulatorHasKey(elements_[i - 1], key)) return false;
   }
   elements_.back()->push_back(key);
   length_++;
   return true;
 }
 
-
 bool KeyAccumulator::AddStringKey(Handle<Object> key,
                                   AddKeyConversion convert) {
   if (string_properties_.is_null()) {
     string_properties_ = OrderedHashSet::Allocate(isolate_, 16);
   }
   // TODO(cbruni): remove this conversion once we throw the correct TypeError
   // for non-string/symbol elements returned by proxies
   if (convert == PROXY_MAGIC && key->IsNumber()) {
     key = isolate_->factory()->NumberToString(key);
   }
   int prev_size = string_properties_->NumberOfElements();
   string_properties_ = OrderedHashSet::Add(string_properties_, key);
   if (prev_size < string_properties_->NumberOfElements()) {
     length_++;
     level_string_length_++;
     return true;
   } else {
     return false;
   }
 }
 
-
 bool KeyAccumulator::AddSymbolKey(Handle<Object> key) {
   if (symbol_properties_.is_null()) {
     symbol_properties_ = OrderedHashSet::Allocate(isolate_, 16);
   }
   int prev_size = symbol_properties_->NumberOfElements();
   symbol_properties_ = OrderedHashSet::Add(symbol_properties_, key);
   if (prev_size < symbol_properties_->NumberOfElements()) {
     length_++;
     level_symbol_length_++;
     return true;
   } else {
     return false;
   }
 }
 
-
 void KeyAccumulator::AddKeys(Handle<FixedArray> array,
                              AddKeyConversion convert) {
   int add_length = array->length();
   if (add_length == 0) return;
   for (int i = 0; i < add_length; i++) {
     Handle<Object> current(array->get(i), isolate_);
     AddKey(current, convert);
   }
 }
 
-
 void KeyAccumulator::AddKeys(Handle<JSObject> array_like,
                              AddKeyConversion convert) {
   DCHECK(array_like->IsJSArray() || array_like->HasSloppyArgumentsElements());
   ElementsAccessor* accessor = array_like->GetElementsAccessor();
   accessor->AddElementsToKeyAccumulator(array_like, this, convert);
 }
 
-
 void KeyAccumulator::AddKeysFromProxy(Handle<JSObject> array_like) {
   // Proxies define a complete list of keys with no distinction of
   // elements and properties, which breaks the normal assumption for the
   // KeyAccumulator.
   AddKeys(array_like, PROXY_MAGIC);
   // Invert the current length to indicate a present proxy, so we can ignore
   // element keys for this level. Otherwise we would not fully respect the order
   // given by the proxy.
   level_string_length_ = -level_string_length_;
 }
@@ skipping 45 matching lines @@
   } else {
     AddKeys(keys, PROXY_MAGIC);
   }
   // Invert the current length to indicate a present proxy, so we can ignore
   // element keys for this level. Otherwise we would not fully respect the order
   // given by the proxy.
   level_string_length_ = -level_string_length_;
   return Just(true);
 }
 
-
 void KeyAccumulator::AddElementKeysFromInterceptor(
     Handle<JSObject> array_like) {
   AddKeys(array_like, CONVERT_TO_ARRAY_INDEX);
   // The interceptor might introduce duplicates for the current level, since
   // these keys get added after the objects's normal element keys.
   SortCurrentElementsListRemoveDuplicates();
 }
 
-
 void KeyAccumulator::SortCurrentElementsListRemoveDuplicates() {
   // Sort and remove duplicates from the current elements level and adjust.
   // the lengths accordingly.
   auto last_level = elements_.back();
   size_t nof_removed_keys = last_level->size();
   std::sort(last_level->begin(), last_level->end());
   last_level->erase(std::unique(last_level->begin(), last_level->end()),
                     last_level->end());
   // Adjust total length by the number of removed duplicates.
   nof_removed_keys -= last_level->size();
   length_ -= static_cast<int>(nof_removed_keys);
 }
 
-
 void KeyAccumulator::SortCurrentElementsList() {
   if (elements_.empty()) return;
   auto element_keys = elements_.back();
   std::sort(element_keys->begin(), element_keys->end());
 }
 
-
 void KeyAccumulator::NextPrototype() {
   // Store the protoLength on the first call of this method.
   if (!elements_.empty()) {
     level_lengths_.push_back(level_string_length_);
     level_lengths_.push_back(level_symbol_length_);
   }
   elements_.push_back(new std::vector<uint32_t>());
   level_string_length_ = 0;
   level_symbol_length_ = 0;
 }
 
+// ============================================================================
+void FastKeyAccumulator::UseVars() {
+  USE(type_);
+  USE(filter_);
+}
+
+namespace {
+
+bool TrySettingEmptyEnumCache(JSReceiver* object) {
+  Map* map = object->map();
+  if (!map->OnlyHasSimpleProperties()) return false;
+  if (map->IsJSProxyMap()) return false;
+  if (map->NumberOfOwnDescriptors() > 0) {
+    int number_of_enumerable_own_properties =
+        map->NumberOfDescribedProperties(OWN_DESCRIPTORS, ENUMERABLE_STRINGS);
+    if (number_of_enumerable_own_properties > 0) return false;
+  }
+  DCHECK(object->IsJSObject());
+  if (JSObject::cast(object)->HasEnumerableElements()) return false;
+  object->map()->SetEnumLength(0);
+  return true;
+}
+
+bool CheckAndInitalizeSimpleEnumCache(JSReceiver* object) {
+  int enum_length = object->map()->EnumLength();
+  if (enum_length == kInvalidEnumCacheSentinel) {
+    return TrySettingEmptyEnumCache(object);
+  } else if (enum_length == 0) {
+    DCHECK(object->IsJSObject());
+    return !JSObject::cast(object)->HasEnumerableElements();
+  }
+  return false;
+}
+}  // namespace
+
+void FastKeyAccumulator::Prepare() {
+  DisallowHeapAllocation no_gc;
+  // Directly go for the fast path for OWN_ONLY keys.
+  if (type_ == OWN_ONLY) return;
+  // Fully walk the prototype chain and find the last prototype with keys.
+  is_simple_enum_ = false;
+  has_empty_prototype_ = true;
+  JSReceiver* first_non_empty_prototype;
+
+  for (PrototypeIterator iter(isolate_, *receiver_,
+                              PrototypeIterator::START_AT_PROTOTYPE);
+       !iter.IsAtEnd(); iter.Advance()) {
+    JSReceiver* current = iter.GetCurrent<JSReceiver>();
+    if (CheckAndInitalizeSimpleEnumCache(current)) continue;
+    has_empty_prototype_ = false;
+    first_non_empty_prototype = current;
+    return;
+  }
+  DCHECK(has_empty_prototype_);
+  if (receiver_->map()->EnumLength() != kInvalidEnumCacheSentinel) {
+    is_simple_enum_ = !JSObject::cast(*receiver_)->HasEnumerableElements();
+  }
+}
+
+namespace {
+Handle<FixedArray> GetOwnKeysWithElements(Isolate* isolate,
+                                          Handle<JSObject> object,
+                                          GetKeysConversion convert) {
+  Handle<FixedArray> keys = JSObject::GetFastEnumPropertyKeys(isolate, object);
+  ElementsAccessor* accessor = object->GetElementsAccessor();
+  return accessor->PrependElementIndices(object, keys, convert);
+}
+
+MaybeHandle<FixedArray> GetOwnKeysWithUninitializedEnumCache(
+    Isolate* isolate, Handle<JSObject> object) {
+  // Uninitalized enum cache
+  Map* map = object->map();
+  if (object->elements() != isolate->heap()->empty_fixed_array() ||
+      object->elements() != isolate->heap()->empty_slow_element_dictionary()) {
+    // TODO(cbruni): avoud HasEnumerableElements for very large holey elements.

[Toon Verwaest, 2016/02/24 15:07:06]

avoid

+    if (object->HasEnumerableElements()) return MaybeHandle<FixedArray>();
+  }
+  int number_of_own_descriptors = map->NumberOfOwnDescriptors();
+  if (number_of_own_descriptors == 0) {
+    map->SetEnumLength(0);
+    return isolate->factory()->empty_fixed_array();
+  }
+  // We have no elements but possibly enumerable property keys, hence we can
+  // directly initialize the enum cache.
+  return JSObject::GetFastEnumPropertyKeys(isolate, object);
+}
+
+}  // namespace
+
+MaybeHandle<FixedArray> FastKeyAccumulator::GetKeys(GetKeysConversion convert) {
+  Handle<FixedArray> keys;
+  if (GetKeysFast(convert).ToHandle(&keys)) {
+    return keys;
+  }
+  return GetKeysSlow(convert);
+}
+
+MaybeHandle<FixedArray> FastKeyAccumulator::GetKeysFast(
+    GetKeysConversion convert) {
+  bool own_only = has_empty_prototype_ || type_ == OWN_ONLY;
+  if (!own_only || receiver_->IsJSProxy() ||
+      !receiver_->map()->OnlyHasSimpleProperties()) {
+    return MaybeHandle<FixedArray>();
+  }
+
+  Handle<FixedArray> keys;
+  DCHECK(receiver_->IsJSObject());
+  Handle<JSObject> object = Handle<JSObject>::cast(receiver_);
+
+  int enum_length = receiver_->map()->EnumLength();
+  if (enum_length == kInvalidEnumCacheSentinel) {
+    // Try initializing the enum cache and return own properties.
+    if (GetOwnKeysWithUninitializedEnumCache(isolate_, object)
+            .ToHandle(&keys)) {
+      is_simple_enum_ =
+          object->map()->EnumLength() != kInvalidEnumCacheSentinel;
+      return keys;
+    }
+  }
+  DCHECK(object->HasEnumerableElements());
+  return GetOwnKeysWithElements(isolate_, object, convert);
+}
+
+MaybeHandle<FixedArray> FastKeyAccumulator::GetKeysSlow(
+    GetKeysConversion convert) {
+  return JSReceiver::GetKeys(receiver_, type_, ENUMERABLE_STRINGS);
+}
 
 }  // namespace internal
 }  // namespace v8