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

src/key-accumulator.cc

Index: src/key-accumulator.cc
diff --git a/src/key-accumulator.cc b/src/key-accumulator.cc
index c2c49969229de3f603ea8494b4543696fef10855..becdda15f2be2ba25822a1303daffe00abc9d837 100644
--- a/src/key-accumulator.cc
+++ b/src/key-accumulator.cc
@@ -9,19 +9,17 @@
 #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();
@@ -99,7 +97,6 @@ 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;
@@ -136,10 +133,8 @@ bool KeyAccumulator::AddKey(Handle<Object> key, AddKeyConversion convert) {
   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
@@ -154,7 +149,6 @@ bool KeyAccumulator::AddIntegerKey(uint32_t key) {
   return true;
 }
 
-
 bool KeyAccumulator::AddStringKey(Handle<Object> key,
                                   AddKeyConversion convert) {
   if (string_properties_.is_null()) {
@@ -176,7 +170,6 @@ bool KeyAccumulator::AddStringKey(Handle<Object> key,
   }
 }
 
-
 bool KeyAccumulator::AddSymbolKey(Handle<Object> key) {
   if (symbol_properties_.is_null()) {
     symbol_properties_ = OrderedHashSet::Allocate(isolate_, 16);
@@ -192,7 +185,6 @@ bool KeyAccumulator::AddSymbolKey(Handle<Object> key) {
   }
 }
 
-
 void KeyAccumulator::AddKeys(Handle<FixedArray> array,
                              AddKeyConversion convert) {
   int add_length = array->length();
@@ -203,7 +195,6 @@ void KeyAccumulator::AddKeys(Handle<FixedArray> array,
   }
 }
 
-
 void KeyAccumulator::AddKeys(Handle<JSObject> array_like,
                              AddKeyConversion convert) {
   DCHECK(array_like->IsJSArray() || array_like->HasSloppyArgumentsElements());
@@ -211,7 +202,6 @@ void KeyAccumulator::AddKeys(Handle<JSObject> array_like,
   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
@@ -277,7 +267,6 @@ Maybe<bool> KeyAccumulator::AddKeysFromProxy(Handle<JSProxy> proxy,
   return Just(true);
 }
 
-
 void KeyAccumulator::AddElementKeysFromInterceptor(
     Handle<JSObject> array_like) {
   AddKeys(array_like, CONVERT_TO_ARRAY_INDEX);
@@ -286,7 +275,6 @@ void KeyAccumulator::AddElementKeysFromInterceptor(
   SortCurrentElementsListRemoveDuplicates();
 }
 
-
 void KeyAccumulator::SortCurrentElementsListRemoveDuplicates() {
   // Sort and remove duplicates from the current elements level and adjust.
   // the lengths accordingly.
@@ -300,14 +288,12 @@ void KeyAccumulator::SortCurrentElementsListRemoveDuplicates() {
   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()) {
@@ -319,6 +305,133 @@ void KeyAccumulator::NextPrototype() {
   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