Use GetProperty for getting elements.

src/elements.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/arguments.h"
 #include "src/conversions.h"
 #include "src/elements.h"
 #include "src/messages.h"
@@ skipping 567 matching lines @@
     ElementsAccessorSubclass::ValidateContents(holder, length);
   }
 
   void Validate(Handle<JSObject> holder) final {
     DisallowHeapAllocation no_gc;
     ElementsAccessorSubclass::ValidateImpl(holder);
   }
 
   static bool HasElementImpl(Handle<JSObject> holder, uint32_t key,
                              Handle<FixedArrayBase> backing_store) {
-    return ElementsAccessorSubclass::GetAttributesImpl(holder, key,
-                                                       backing_store) != ABSENT;
+    return ElementsAccessorSubclass::GetAttributesImpl(
+               *holder, key, *backing_store) != ABSENT;
   }
 
   virtual bool HasElement(Handle<JSObject> holder, uint32_t key,
                           Handle<FixedArrayBase> backing_store) final {
     return ElementsAccessorSubclass::HasElementImpl(holder, key, backing_store);
   }
 
-  MUST_USE_RESULT virtual MaybeHandle<Object> Get(
-      Handle<Object> receiver, Handle<JSObject> holder, uint32_t key,
-      Handle<FixedArrayBase> backing_store) final {
+  virtual Handle<Object> Get(Handle<Object> receiver, Handle<JSObject> holder,
+                             uint32_t key,
+                             Handle<FixedArrayBase> backing_store) final {
     if (!IsExternalArrayElementsKind(ElementsTraits::Kind) &&
         FLAG_trace_js_array_abuse) {
       CheckArrayAbuse(holder, "elements read", key);
     }
 
     if (IsExternalArrayElementsKind(ElementsTraits::Kind) &&
         FLAG_trace_external_array_abuse) {
       CheckArrayAbuse(holder, "external elements read", key);
     }
 
     return ElementsAccessorSubclass::GetImpl(
         receiver, holder, key, backing_store);
   }
 
-  MUST_USE_RESULT static MaybeHandle<Object> GetImpl(
-      Handle<Object> receiver,
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) {
+  static Handle<Object> GetImpl(Handle<Object> receiver, Handle<JSObject> obj,
+                                uint32_t key,
+                                Handle<FixedArrayBase> backing_store) {
     if (key < ElementsAccessorSubclass::GetCapacityImpl(*obj, *backing_store)) {
       return BackingStore::get(Handle<BackingStore>::cast(backing_store), key);
     } else {
       return backing_store->GetIsolate()->factory()->the_hole_value();
     }
   }
 
-  MUST_USE_RESULT virtual PropertyAttributes GetAttributes(
-      Handle<JSObject> holder, uint32_t key,
-      Handle<FixedArrayBase> backing_store) final {
+  virtual PropertyAttributes GetAttributes(
+      JSObject* holder, uint32_t key, FixedArrayBase* backing_store) final {
     return ElementsAccessorSubclass::GetAttributesImpl(holder, key,
                                                        backing_store);
   }
 
-  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
-        Handle<JSObject> obj,
-        uint32_t key,
-        Handle<FixedArrayBase> backing_store) {
-    if (key >=
-        ElementsAccessorSubclass::GetCapacityImpl(*obj, *backing_store)) {
+  static PropertyAttributes GetAttributesImpl(JSObject* obj, uint32_t key,
+                                              FixedArrayBase* backing_store) {
+    if (key >= ElementsAccessorSubclass::GetCapacityImpl(obj, backing_store)) {
       return ABSENT;
     }
-    return
-        Handle<BackingStore>::cast(backing_store)->is_the_hole(key)
-          ? ABSENT : NONE;
+    return BackingStore::cast(backing_store)->is_the_hole(key) ? ABSENT : NONE;
   }
 
-  MUST_USE_RESULT virtual MaybeHandle<AccessorPair> GetAccessorPair(
+  virtual MaybeHandle<AccessorPair> GetAccessorPair(
       Handle<JSObject> holder, uint32_t key,
       Handle<FixedArrayBase> backing_store) final {
     return ElementsAccessorSubclass::GetAccessorPairImpl(holder, key,
                                                          backing_store);
   }
 
-  MUST_USE_RESULT static MaybeHandle<AccessorPair> GetAccessorPairImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
+  static MaybeHandle<AccessorPair> GetAccessorPairImpl(
+      Handle<JSObject> obj, uint32_t key,
       Handle<FixedArrayBase> backing_store) {
     return MaybeHandle<AccessorPair>();
   }
 
   MUST_USE_RESULT virtual MaybeHandle<Object> SetLength(
       Handle<JSArray> array, Handle<Object> length) final {
     return ElementsAccessorSubclass::SetLengthImpl(
         array, length, handle(array->elements()));
   }
 
@@ skipping 61 matching lines @@
     // intentionally to avoid ArrayConcat() builtin performance degradation.
     //
     // Details: The idea is that allocations actually happen only in case of
     // copying from object with fast double elements to object with object
     // elements. In all the other cases there are no allocations performed and
     // handle creation causes noticeable performance degradation of the builtin.
     ElementsAccessorSubclass::CopyElementsImpl(
         from, from_start, *to, from_kind, to_start, packed_size, copy_size);
   }
 
-  virtual MaybeHandle<FixedArray> AddElementsToFixedArray(
+  virtual Handle<FixedArray> AddElementsToFixedArray(
       Handle<JSObject> receiver, Handle<FixedArray> to,
       FixedArray::KeyFilter filter) final {
     Handle<FixedArrayBase> from(receiver->elements());
 
     int len0 = to->length();
 #ifdef ENABLE_SLOW_DCHECKS
     if (FLAG_enable_slow_asserts) {
       for (int i = 0; i < len0; i++) {
         DCHECK(!to->get(i)->IsTheHole());
       }
     }
 #endif
 
     // Optimize if 'other' is empty.
     // We cannot optimize if 'this' is empty, as other may have holes.
     uint32_t len1 = ElementsAccessorSubclass::GetCapacityImpl(*receiver, *from);
     if (len1 == 0) return to;
 
     Isolate* isolate = from->GetIsolate();
 
     // Compute how many elements are not in other.
     uint32_t extra = 0;
     for (uint32_t y = 0; y < len1; y++) {
       uint32_t key = ElementsAccessorSubclass::GetKeyForIndexImpl(*from, y);
       if (ElementsAccessorSubclass::HasElementImpl(receiver, key, from)) {
-        Handle<Object> value;
-        ASSIGN_RETURN_ON_EXCEPTION(
-            isolate, value,
-            ElementsAccessorSubclass::GetImpl(receiver, receiver, key, from),
-            FixedArray);
+        Handle<Object> value =
+            ElementsAccessorSubclass::GetImpl(receiver, receiver, key, from);
 
         DCHECK(!value->IsTheHole());
+        DCHECK(!value->IsAccessorPair());
+        DCHECK(!value->IsExecutableAccessorInfo());
         if (filter == FixedArray::NON_SYMBOL_KEYS && value->IsSymbol()) {
           continue;
         }
         if (!HasKey(to, value)) {
           extra++;
         }
       }
     }
 
     if (extra == 0) return to;
 
     // Allocate the result
     Handle<FixedArray> result = isolate->factory()->NewFixedArray(len0 + extra);
 
     // Fill in the content
     {
       DisallowHeapAllocation no_gc;
       WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
       for (int i = 0; i < len0; i++) {
         Object* e = to->get(i);
         DCHECK(e->IsString() || e->IsNumber());
         result->set(i, e, mode);
       }
     }
     // Fill in the extra values.
     uint32_t index = 0;
     for (uint32_t y = 0; y < len1; y++) {
       uint32_t key = ElementsAccessorSubclass::GetKeyForIndexImpl(*from, y);
       if (ElementsAccessorSubclass::HasElementImpl(receiver, key, from)) {
-        Handle<Object> value;
-        ASSIGN_RETURN_ON_EXCEPTION(
-            isolate, value,
-            ElementsAccessorSubclass::GetImpl(receiver, receiver, key, from),
-            FixedArray);
+        Handle<Object> value =
+            ElementsAccessorSubclass::GetImpl(receiver, receiver, key, from);
+        DCHECK(!value->IsAccessorPair());
+        DCHECK(!value->IsExecutableAccessorInfo());
         if (filter == FixedArray::NON_SYMBOL_KEYS && value->IsSymbol()) {
           continue;
         }
         if (!value->IsTheHole() && !HasKey(to, value)) {
           result->set(len0 + index, *value);
           index++;
         }
       }
     }
     DCHECK(extra == index);
@@ skipping 453 matching lines @@
       : ElementsAccessorBase<AccessorClass,
                              ElementsKindTraits<Kind> >(name) {}
 
  protected:
   typedef typename ElementsKindTraits<Kind>::BackingStore BackingStore;
   typedef TypedElementsAccessor<Kind> AccessorClass;
 
   friend class ElementsAccessorBase<AccessorClass,
                                     ElementsKindTraits<Kind> >;
 
-  MUST_USE_RESULT static MaybeHandle<Object> GetImpl(
-      Handle<Object> receiver,
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) {
+  static Handle<Object> GetImpl(Handle<Object> receiver, Handle<JSObject> obj,
+                                uint32_t key,
+                                Handle<FixedArrayBase> backing_store) {
     if (key < AccessorClass::GetCapacityImpl(*obj, *backing_store)) {
       return BackingStore::get(Handle<BackingStore>::cast(backing_store), key);
     } else {
       return backing_store->GetIsolate()->factory()->undefined_value();
     }
   }
 
-  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) {
-    return key < AccessorClass::GetCapacityImpl(*obj, *backing_store) ? NONE
-                                                                      : ABSENT;
+  static PropertyAttributes GetAttributesImpl(JSObject* obj, uint32_t key,
+                                              FixedArrayBase* backing_store) {
+    return key < AccessorClass::GetCapacityImpl(obj, backing_store) ? NONE
+                                                                    : ABSENT;
   }
 
   MUST_USE_RESULT static MaybeHandle<Object> SetLengthImpl(
       Handle<JSObject> obj,
       Handle<Object> length,
       Handle<FixedArrayBase> backing_store) {
     // External arrays do not support changing their length.
     UNREACHABLE();
     return obj;
   }
@@ skipping 150 matching lines @@
 
  protected:
   friend class ElementsAccessorBase<DictionaryElementsAccessor,
                                     ElementsKindTraits<DICTIONARY_ELEMENTS> >;
 
   MUST_USE_RESULT virtual MaybeHandle<Object> Delete(
       Handle<JSObject> obj, uint32_t key, LanguageMode language_mode) final {
     return DeleteCommon(obj, key, language_mode);
   }
 
-  MUST_USE_RESULT static MaybeHandle<Object> GetImpl(
-      Handle<Object> receiver,
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> store) {
+  static Handle<Object> GetImpl(Handle<Object> receiver, Handle<JSObject> obj,
+                                uint32_t key, Handle<FixedArrayBase> store) {
     Handle<SeededNumberDictionary> backing_store =
         Handle<SeededNumberDictionary>::cast(store);
     Isolate* isolate = backing_store->GetIsolate();
     int entry = backing_store->FindEntry(key);
     if (entry != SeededNumberDictionary::kNotFound) {
-      Handle<Object> element(backing_store->ValueAt(entry), isolate);
-      PropertyDetails details = backing_store->DetailsAt(entry);
-      if (details.type() == ACCESSOR_CONSTANT) {
-        return JSObject::GetElementWithCallback(
-            obj, receiver, element, key, obj);
-      } else {
-        return element;
-      }
+      return handle(backing_store->ValueAt(entry), isolate);
     }
     return isolate->factory()->the_hole_value();
   }
 
-  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) {
-    Handle<SeededNumberDictionary> dictionary =
-        Handle<SeededNumberDictionary>::cast(backing_store);
+  static PropertyAttributes GetAttributesImpl(JSObject* obj, uint32_t key,
+                                              FixedArrayBase* backing_store) {
+    SeededNumberDictionary* dictionary =
+        SeededNumberDictionary::cast(backing_store);
     int entry = dictionary->FindEntry(key);
     if (entry != SeededNumberDictionary::kNotFound) {
       return dictionary->DetailsAt(entry).attributes();
     }
     return ABSENT;
   }
 
-  MUST_USE_RESULT static MaybeHandle<AccessorPair> GetAccessorPairImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> store) {
+  static MaybeHandle<AccessorPair> GetAccessorPairImpl(
+      Handle<JSObject> obj, uint32_t key, Handle<FixedArrayBase> store) {
     Handle<SeededNumberDictionary> backing_store =
         Handle<SeededNumberDictionary>::cast(store);
     int entry = backing_store->FindEntry(key);
     if (entry != SeededNumberDictionary::kNotFound &&
         backing_store->DetailsAt(entry).type() == ACCESSOR_CONSTANT &&
         backing_store->ValueAt(entry)->IsAccessorPair()) {
       return handle(AccessorPair::cast(backing_store->ValueAt(entry)));
     }
     return MaybeHandle<AccessorPair>();
   }
@@ skipping 35 matching lines @@
  public:
   explicit SloppyArgumentsElementsAccessor(const char* name)
       : ElementsAccessorBase<
           SloppyArgumentsElementsAccessor,
           ElementsKindTraits<SLOPPY_ARGUMENTS_ELEMENTS> >(name) {}
  protected:
   friend class ElementsAccessorBase<
       SloppyArgumentsElementsAccessor,
       ElementsKindTraits<SLOPPY_ARGUMENTS_ELEMENTS> >;
 
-  MUST_USE_RESULT static MaybeHandle<Object> GetImpl(
-      Handle<Object> receiver,
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> parameters) {
+  static Handle<Object> GetImpl(Handle<Object> receiver, Handle<JSObject> obj,
+                                uint32_t key,
+                                Handle<FixedArrayBase> parameters) {
     Isolate* isolate = obj->GetIsolate();
     Handle<FixedArray> parameter_map = Handle<FixedArray>::cast(parameters);
-    Handle<Object> probe = GetParameterMapArg(obj, parameter_map, key);
+    Handle<Object> probe(GetParameterMapArg(*parameter_map, key), isolate);
     if (!probe->IsTheHole()) {
       DisallowHeapAllocation no_gc;
       Context* context = Context::cast(parameter_map->get(0));
       int context_index = Handle<Smi>::cast(probe)->value();
       DCHECK(!context->get(context_index)->IsTheHole());
       return handle(context->get(context_index), isolate);
     } else {
       // Object is not mapped, defer to the arguments.
       Handle<FixedArray> arguments(FixedArray::cast(parameter_map->get(1)),
                                    isolate);
-      Handle<Object> result;
-      ASSIGN_RETURN_ON_EXCEPTION(
-          isolate, result,
-          ElementsAccessor::ForArray(arguments)->Get(
-              receiver, obj, key, arguments),
-          Object);
+      Handle<Object> result = ElementsAccessor::ForArray(arguments)
+                                  ->Get(receiver, obj, key, arguments);
       // Elements of the arguments object in slow mode might be slow aliases.
       if (result->IsAliasedArgumentsEntry()) {
         DisallowHeapAllocation no_gc;
         AliasedArgumentsEntry* entry = AliasedArgumentsEntry::cast(*result);
         Context* context = Context::cast(parameter_map->get(0));
         int context_index = entry->aliased_context_slot();
         DCHECK(!context->get(context_index)->IsTheHole());
         return handle(context->get(context_index), isolate);
       } else {
         return result;
       }
     }
   }
 
-  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> backing_store) {
-    Handle<FixedArray> parameter_map = Handle<FixedArray>::cast(backing_store);
-    Handle<Object> probe = GetParameterMapArg(obj, parameter_map, key);
+  static PropertyAttributes GetAttributesImpl(JSObject* obj, uint32_t key,
+                                              FixedArrayBase* backing_store) {
+    FixedArray* parameter_map = FixedArray::cast(backing_store);
+    Object* probe = GetParameterMapArg(parameter_map, key);
     if (!probe->IsTheHole()) {
       return NONE;
     } else {
       // If not aliased, check the arguments.
-      Handle<FixedArray> arguments(FixedArray::cast(parameter_map->get(1)));
+      FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
       return ElementsAccessor::ForArray(arguments)
           ->GetAttributes(obj, key, arguments);
     }
   }
 
-  MUST_USE_RESULT static MaybeHandle<AccessorPair> GetAccessorPairImpl(
-      Handle<JSObject> obj,
-      uint32_t key,
-      Handle<FixedArrayBase> parameters) {
+  static MaybeHandle<AccessorPair> GetAccessorPairImpl(
+      Handle<JSObject> obj, uint32_t key, Handle<FixedArrayBase> parameters) {
     Handle<FixedArray> parameter_map = Handle<FixedArray>::cast(parameters);
-    Handle<Object> probe = GetParameterMapArg(obj, parameter_map, key);
+    Handle<Object> probe(GetParameterMapArg(*parameter_map, key),
+                         obj->GetIsolate());
     if (!probe->IsTheHole()) {
       return MaybeHandle<AccessorPair>();
     } else {
       // If not aliased, check the arguments.
       Handle<FixedArray> arguments(FixedArray::cast(parameter_map->get(1)));
       return ElementsAccessor::ForArray(arguments)
           ->GetAccessorPair(obj, key, arguments);
     }
   }
 
   MUST_USE_RESULT static MaybeHandle<Object> SetLengthImpl(
       Handle<JSObject> obj,
       Handle<Object> length,
       Handle<FixedArrayBase> parameter_map) {
     // TODO(mstarzinger): This was never implemented but will be used once we
     // correctly implement [[DefineOwnProperty]] on arrays.
     UNIMPLEMENTED();
     return obj;
   }
 
   MUST_USE_RESULT virtual MaybeHandle<Object> Delete(
       Handle<JSObject> obj, uint32_t key, LanguageMode language_mode) final {
     Isolate* isolate = obj->GetIsolate();
     Handle<FixedArray> parameter_map(FixedArray::cast(obj->elements()));
-    Handle<Object> probe = GetParameterMapArg(obj, parameter_map, key);
+    Handle<Object> probe(GetParameterMapArg(*parameter_map, key), isolate);
     if (!probe->IsTheHole()) {
       // TODO(kmillikin): We could check if this was the last aliased
       // parameter, and revert to normal elements in that case.  That
       // would enable GC of the context.
       parameter_map->set_the_hole(key + 2);
     } else {
       Handle<FixedArray> arguments(FixedArray::cast(parameter_map->get(1)));
       if (arguments->IsDictionary()) {
         return DictionaryElementsAccessor::DeleteCommon(obj, key,
                                                         language_mode);
@@ skipping 17 matching lines @@
 
   static uint32_t GetCapacityImpl(JSObject* holder,
                                   FixedArrayBase* backing_store) {
     FixedArray* parameter_map = FixedArray::cast(backing_store);
     FixedArrayBase* arguments = FixedArrayBase::cast(parameter_map->get(1));
     return Max(static_cast<uint32_t>(parameter_map->length() - 2),
                ForArray(arguments)->GetCapacity(holder, arguments));
   }
 
   static uint32_t GetKeyForIndexImpl(FixedArrayBase* dict, uint32_t index) {
     return index;

[Igor Sheludko, 2015/05/26 17:11:56]

I think we should not break this invariant:
DCHECK_EQ(key, GetKeyForIndexImpl(parameters, GetIndexForKeyImpl(parameters,
key));

Currently we don't convert keys to indices and back, but if we ever do...

   }
 
-  static uint32_t GetIndexForKeyImpl(FixedArrayBase* dict, uint32_t key) {
-    return key;
+  static uint32_t GetIndexForKeyImpl(FixedArrayBase* parameters, uint32_t key) {
+    FixedArray* parameter_map = FixedArray::cast(parameters);
+    Object* probe = GetParameterMapArg(parameter_map, key);
+    if (!probe->IsTheHole()) {
+      return key;
+    } else {
+      uint32_t length = parameter_map->length();
+      FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
+      return length +
+             ElementsAccessor::ForArray(arguments)
+                 ->GetIndexForKey(arguments, key);
+    }
   }
 
-  static PropertyDetails GetDetailsImpl(FixedArrayBase* backing_store,
+  static PropertyDetails GetDetailsImpl(FixedArrayBase* parameters,
                                         uint32_t index) {
-    return PropertyDetails(NONE, DATA, 0, PropertyCellType::kNoCell);
+    FixedArray* parameter_map = FixedArray::cast(parameters);
+    uint32_t length = parameter_map->length();
+    if (index < length) {
+      return PropertyDetails(NONE, DATA, 0, PropertyCellType::kNoCell);
+    }
+    index -= length;
+    FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
+    return ElementsAccessor::ForArray(arguments)->GetDetails(arguments, index);
   }
 
-
  private:
-  static Handle<Object> GetParameterMapArg(Handle<JSObject> holder,
-                                           Handle<FixedArray> parameter_map,
-                                           uint32_t key) {
-    Isolate* isolate = holder->GetIsolate();
-    uint32_t length = holder->IsJSArray()
-        ? Smi::cast(Handle<JSArray>::cast(holder)->length())->value()
-        : parameter_map->length();
+  static Object* GetParameterMapArg(FixedArray* parameter_map, uint32_t key) {
+    uint32_t length = parameter_map->length();
     return key < (length - 2)
-        ? handle(parameter_map->get(key + 2), isolate)
-        : Handle<Object>::cast(isolate->factory()->the_hole_value());
+               ? parameter_map->get(key + 2)
+               : Object::cast(parameter_map->GetHeap()->the_hole_value());
   }
 };
 
 
 ElementsAccessor* ElementsAccessor::ForArray(FixedArrayBase* array) {
   return elements_accessors_[ElementsKindForArray(array)];
 }
 
 
 ElementsAccessor* ElementsAccessor::ForArray(Handle<FixedArrayBase> array) {
@@ skipping 60 matching lines @@
       }
     } else {
       return ThrowArrayLengthRangeError(isolate);
     }
   }
 
   // Slow case: The new length does not fit into a Smi or conversion
   // to slow elements is needed for other reasons.
   if (length->IsNumber()) {
     uint32_t value;
-    if (length->ToArrayIndex(&value)) {
+    if (length->ToArrayLength(&value)) {
       Handle<SeededNumberDictionary> dictionary =
           JSObject::NormalizeElements(array);
       DCHECK(!dictionary.is_null());
 
       Handle<Object> new_length = DictionaryElementsAccessor::
           SetLengthWithoutNormalize(dictionary, array, length, value);
       DCHECK(!new_length.is_null());
 
       DCHECK(new_length->IsNumber());
       array->set_length(*new_length);
@@ skipping 98 matching lines @@
       UNREACHABLE();
       break;
   }
 
   array->set_elements(*elms);
   array->set_length(Smi::FromInt(number_of_elements));
   return array;
 }
 
 } }  // namespace v8::internal