- A prototype which allows to expose CanvasPixelArray functionality...

src/objects.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 988 matching lines @@
   switch (map()->instance_type()) {
     case MAP_TYPE:
       accumulator->Add("<Map>");
       break;
     case FIXED_ARRAY_TYPE:
       accumulator->Add("<FixedArray[%u]>", FixedArray::cast(this)->length());
       break;
     case BYTE_ARRAY_TYPE:
       accumulator->Add("<ByteArray[%u]>", ByteArray::cast(this)->length());
       break;
+    case PIXEL_ARRAY_TYPE:
+      accumulator->Add("<PixelArray[%u]>", PixelArray::cast(this)->length());
+      break;
     case SHARED_FUNCTION_INFO_TYPE:
       accumulator->Add("<SharedFunctionInfo>");
       break;
 #define MAKE_STRUCT_CASE(NAME, Name, name) \
   case NAME##_TYPE:                        \
     accumulator->Put('<');                 \
     accumulator->Add(#Name);               \
     accumulator->Put('>');                 \
     break;
   STRUCT_LIST(MAKE_STRUCT_CASE)
@@ skipping 121 matching lines @@
     case CODE_TYPE:
       reinterpret_cast<Code*>(this)->CodeIterateBody(v);
       break;
     case JS_GLOBAL_PROPERTY_CELL_TYPE:
       reinterpret_cast<JSGlobalPropertyCell*>(this)
           ->JSGlobalPropertyCellIterateBody(v);
       break;
     case HEAP_NUMBER_TYPE:
     case FILLER_TYPE:
     case BYTE_ARRAY_TYPE:
+    case PIXEL_ARRAY_TYPE:
       break;
     case SHARED_FUNCTION_INFO_TYPE: {
       SharedFunctionInfo* shared = reinterpret_cast<SharedFunctionInfo*>(this);
       shared->SharedFunctionInfoIterateBody(v);
       break;
     }
 #define MAKE_STRUCT_CASE(NAME, Name, name) \
         case NAME##_TYPE:
       STRUCT_LIST(MAKE_STRUCT_CASE)
 #undef MAKE_STRUCT_CASE
@@ skipping 502 matching lines @@
     }
   }
   result->NotFound();
 }
 
 
 Object* JSObject::LookupCallbackSetterInPrototypes(uint32_t index) {
   for (Object* pt = GetPrototype();
        pt != Heap::null_value();
        pt = pt->GetPrototype()) {
-    if (JSObject::cast(pt)->HasFastElements()) continue;
+    if (!JSObject::cast(pt)->HasDictionaryElements()) {
+        continue;
+    }
     NumberDictionary* dictionary = JSObject::cast(pt)->element_dictionary();
     int entry = dictionary->FindEntry(index);
     if (entry != NumberDictionary::kNotFound) {
       Object* element = dictionary->ValueAt(entry);
       PropertyDetails details = dictionary->DetailsAt(entry);
       if (details.type() == CALLBACKS) {
         // Only accessors allowed as elements.
         return FixedArray::cast(element)->get(kSetterIndex);
       }
     }
@@ skipping 541 matching lines @@
 
 Object* JSObject::TransformToFastProperties(int unused_property_fields) {
   if (HasFastProperties()) return this;
   ASSERT(!IsGlobalObject());
   return property_dictionary()->
       TransformPropertiesToFastFor(this, unused_property_fields);
 }
 
 
 Object* JSObject::NormalizeElements() {
-  if (!HasFastElements()) return this;
+  ASSERT(!HasPixelElements());
+  if (HasDictionaryElements()) return this;
 
   // Get number of entries.
   FixedArray* array = FixedArray::cast(elements());
 
   // Compute the effective length.
   int length = IsJSArray() ?
                Smi::cast(JSArray::cast(this)->length())->value() :
                array->length();
   Object* obj = NumberDictionary::Allocate(length);
   if (obj->IsFailure()) return obj;
@@ skipping 65 matching lines @@
   }
   Object* raw_result =
       this_handle->DeletePropertyPostInterceptor(*name_handle, NORMAL_DELETION);
   RETURN_IF_SCHEDULED_EXCEPTION();
   return raw_result;
 }
 
 
 Object* JSObject::DeleteElementPostInterceptor(uint32_t index,
                                                DeleteMode mode) {
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
+  ASSERT(!HasPixelElements());
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
       static_cast<uint32_t>(Smi::cast(JSArray::cast(this)->length())->value()) :
       static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    if (index < length) {
-      FixedArray::cast(elements())->set_the_hole(index);
+      if (index < length) {
+        FixedArray::cast(elements())->set_the_hole(index);
+      }
+      break;
     }
-    return Heap::true_value();
-  }
-  ASSERT(!HasFastElements());
-  NumberDictionary* dictionary = element_dictionary();
-  int entry = dictionary->FindEntry(index);
-  if (entry != NumberDictionary::kNotFound) {
-    return dictionary->DeleteProperty(entry, mode);
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = element_dictionary();
+      int entry = dictionary->FindEntry(index);
+      if (entry != NumberDictionary::kNotFound) {
+        return dictionary->DeleteProperty(entry, mode);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
   return Heap::true_value();
 }
 
 
 Object* JSObject::DeleteElementWithInterceptor(uint32_t index) {
   // Make sure that the top context does not change when doing
   // callbacks or interceptor calls.
   AssertNoContextChange ncc;
   HandleScope scope;
@@ skipping 41 matching lines @@
   }
 
   if (HasIndexedInterceptor()) {
     // Skip interceptor if forcing deletion.
     if (mode == FORCE_DELETION) {
       return DeleteElementPostInterceptor(index, mode);
     }
     return DeleteElementWithInterceptor(index);
   }
 
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
       static_cast<uint32_t>(Smi::cast(JSArray::cast(this)->length())->value()) :
       static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    if (index < length) {
-      FixedArray::cast(elements())->set_the_hole(index);
+      if (index < length) {
+        FixedArray::cast(elements())->set_the_hole(index);
+      }
+      break;
     }
-    return Heap::true_value();
-  } else {
-    NumberDictionary* dictionary = element_dictionary();
-    int entry = dictionary->FindEntry(index);
-    if (entry != NumberDictionary::kNotFound) {
-      return dictionary->DeleteProperty(entry, mode);
+    case PIXEL_ELEMENTS: {
+      // Pixel elements cannot be deleted. Just silently ignore here.
+      break;
     }
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = element_dictionary();
+      int entry = dictionary->FindEntry(index);
+      if (entry != NumberDictionary::kNotFound) {
+        return dictionary->DeleteProperty(entry, mode);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
   return Heap::true_value();
 }
 
 
 Object* JSObject::DeleteProperty(String* name, DeleteMode mode) {
   // ECMA-262, 3rd, 8.6.2.5
   ASSERT(name->IsString());
 
   // Check access rights if needed.
@@ skipping 57 matching lines @@
     return true;
   }
 
   // Check if the object is among the named properties.
   Object* key = SlowReverseLookup(obj);
   if (key != Heap::undefined_value()) {
     return true;
   }
 
   // Check if the object is among the indexed properties.
-  if (HasFastElements()) {
-    int length = IsJSArray()
-        ? Smi::cast(JSArray::cast(this)->length())->value()
-        : FixedArray::cast(elements())->length();
-    for (int i = 0; i < length; i++) {
-      Object* element = FixedArray::cast(elements())->get(i);
-      if (!element->IsTheHole() && element == obj) {
+  switch (GetElementsKind()) {
+    case PIXEL_ELEMENTS:
+      // Raw pixels do not reference other objects.
+      break;
+    case FAST_ELEMENTS: {
+      int length = IsJSArray() ?
+          Smi::cast(JSArray::cast(this)->length())->value() :
+          FixedArray::cast(elements())->length();
+      for (int i = 0; i < length; i++) {
+        Object* element = FixedArray::cast(elements())->get(i);
+        if (!element->IsTheHole() && element == obj) {
+          return true;
+        }
+      }
+      break;
+    }
+    case DICTIONARY_ELEMENTS: {
+      key = element_dictionary()->SlowReverseLookup(obj);
+      if (key != Heap::undefined_value()) {
         return true;
       }
+      break;
     }
-  } else {
-    key = element_dictionary()->SlowReverseLookup(obj);
-    if (key != Heap::undefined_value()) {
-      return true;
-    }
+    default:
+      UNREACHABLE();
+      break;
   }
 
   // For functions check the context. Boilerplate functions do
   // not have to be traversed since they have no real context.
   if (IsJSFunction() && !JSFunction::cast(this)->IsBoilerplate()) {
     // Get the constructor function for arguments array.
     JSObject* arguments_boilerplate =
         Top::context()->global_context()->arguments_boilerplate();
     JSFunction* arguments_function =
         JSFunction::cast(arguments_boilerplate->map()->constructor());
@@ skipping 197 matching lines @@
         AccessorInfo::cast(obj)->prohibits_overwriting()) {
       return Heap::undefined_value();
     }
   }
 
   uint32_t index;
   bool is_element = name->AsArrayIndex(&index);
   if (is_element && IsJSArray()) return Heap::undefined_value();
 
   if (is_element) {
-    // Lookup the index.
-    if (!HasFastElements()) {
-      NumberDictionary* dictionary = element_dictionary();
-      int entry = dictionary->FindEntry(index);
-      if (entry != NumberDictionary::kNotFound) {
-        Object* result = dictionary->ValueAt(entry);
-        PropertyDetails details = dictionary->DetailsAt(entry);
-        if (details.IsReadOnly()) return Heap::undefined_value();
-        if (details.type() == CALLBACKS) {
-          // Only accessors allowed as elements.
-          ASSERT(result->IsFixedArray());
-          return result;
+    switch (GetElementsKind()) {
+      case FAST_ELEMENTS:
+        break;
+      case PIXEL_ELEMENTS:
+        // Ignore getters and setters on pixel elements.
+        return Heap::undefined_value();
+      case DICTIONARY_ELEMENTS: {
+        // Lookup the index.
+        NumberDictionary* dictionary = element_dictionary();
+        int entry = dictionary->FindEntry(index);
+        if (entry != NumberDictionary::kNotFound) {
+          Object* result = dictionary->ValueAt(entry);
+          PropertyDetails details = dictionary->DetailsAt(entry);
+          if (details.IsReadOnly()) return Heap::undefined_value();
+          if (details.type() == CALLBACKS) {
+            // Only accessors allowed as elements.
+            ASSERT(result->IsFixedArray());
+            return result;
+          }
         }
+        break;
       }
+      default:
+        UNREACHABLE();
+        break;
     }
   } else {
     // Lookup the name.
     LookupResult result;
     LocalLookup(name, &result);
     if (result.IsValid()) {
       if (result.IsReadOnly()) return Heap::undefined_value();
       if (result.type() == CALLBACKS) {
         Object* obj = result.GetCallbackObject();
         if (obj->IsFixedArray()) return obj;
@@ skipping 78 matching lines @@
     return Heap::undefined_value();
   }
 
   // Make the lookup and include prototypes.
   int accessor_index = is_getter ? kGetterIndex : kSetterIndex;
   uint32_t index;
   if (name->AsArrayIndex(&index)) {
     for (Object* obj = this;
          obj != Heap::null_value();
          obj = JSObject::cast(obj)->GetPrototype()) {
-      JSObject* jsObject = JSObject::cast(obj);
-      if (!jsObject->HasFastElements()) {
-        NumberDictionary* dictionary = jsObject->element_dictionary();
+      JSObject* js_object = JSObject::cast(obj);
+      if (js_object->HasDictionaryElements()) {
+        NumberDictionary* dictionary = js_object->element_dictionary();
         int entry = dictionary->FindEntry(index);
         if (entry != NumberDictionary::kNotFound) {
           Object* element = dictionary->ValueAt(entry);
           PropertyDetails details = dictionary->DetailsAt(entry);
           if (details.type() == CALLBACKS) {
             // Only accessors allowed as elements.
             return FixedArray::cast(element)->get(accessor_index);
           }
         }
       }
@@ skipping 179 matching lines @@
     if (element->IsString() &&
         key->IsString() && String::cast(element)->Equals(String::cast(key))) {
       return true;
     }
   }
   return false;
 }
 
 
 Object* FixedArray::AddKeysFromJSArray(JSArray* array) {
-  if (array->HasFastElements()) {
-    return UnionOfKeys(array->elements());
+  ASSERT(!array->HasPixelElements());
+  switch (array->GetElementsKind()) {
+    case JSObject::FAST_ELEMENTS:
+      return UnionOfKeys(FixedArray::cast(array->elements()));
+    case JSObject::DICTIONARY_ELEMENTS: {
+      NumberDictionary* dict = array->element_dictionary();
+      int size = dict->NumberOfElements();
+      
+      // Allocate a temporary fixed array.
+      Object* object = Heap::AllocateFixedArray(size);
+      if (object->IsFailure()) return object;
+      FixedArray* key_array = FixedArray::cast(object);
+      
+      int capacity = dict->Capacity();
+      int pos = 0;
+      // Copy the elements from the JSArray to the temporary fixed array.
+      for (int i = 0; i < capacity; i++) {
+        if (dict->IsKey(dict->KeyAt(i))) {
+          key_array->set(pos++, dict->ValueAt(i));
+        }
+      }
+      // Compute the union of this and the temporary fixed array.
+      return UnionOfKeys(key_array);
+    }
+    default:
+      UNREACHABLE();
   }
-  ASSERT(!array->HasFastElements());
-  NumberDictionary* dict = array->element_dictionary();
-  int size = dict->NumberOfElements();
-
-  // Allocate a temporary fixed array.
-  Object* object = Heap::AllocateFixedArray(size);
-  if (object->IsFailure()) return object;
-  FixedArray* key_array = FixedArray::cast(object);
-
-  int capacity = dict->Capacity();
-  int pos = 0;
-  // Copy the elements from the JSArray to the temporary fixed array.
-  for (int i = 0; i < capacity; i++) {
-    if (dict->IsKey(dict->KeyAt(i))) {
-      key_array->set(pos++, dict->ValueAt(i));
-    }
-  }
-  // Compute the union of this and the temporary fixed array.
-  return UnionOfKeys(key_array);
+  UNREACHABLE();
+  return Heap::null_value();  // Failure case needs to "return" a value.
 }
 
 
 Object* FixedArray::UnionOfKeys(FixedArray* other) {
   int len0 = length();
   int len1 = other->length();
   // Optimize if either is empty.
   if (len0 == 0) return other;
   if (len1 == 0) return this;
 
@@ skipping 2018 matching lines @@
 
   PrintF("RelocInfo (size = %d)\n", relocation_size());
   for (RelocIterator it(this); !it.done(); it.next())
     it.rinfo()->Print();
   PrintF("\n");
 }
 #endif  // ENABLE_DISASSEMBLER
 
 
 void JSObject::SetFastElements(FixedArray* elems) {
+  // We should never end in here with a pixel array.
+  ASSERT(!HasPixelElements());
 #ifdef DEBUG
   // Check the provided array is filled with the_hole.
   uint32_t len = static_cast<uint32_t>(elems->length());
   for (uint32_t i = 0; i < len; i++) ASSERT(elems->get(i)->IsTheHole());
 #endif
   WriteBarrierMode mode = elems->GetWriteBarrierMode();
-  if (HasFastElements()) {
-    FixedArray* old_elements = FixedArray::cast(elements());
-    uint32_t old_length = static_cast<uint32_t>(old_elements->length());
-    // Fill out the new array with this content and array holes.
-    for (uint32_t i = 0; i < old_length; i++) {
-      elems->set(i, old_elements->get(i), mode);
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      FixedArray* old_elements = FixedArray::cast(elements());
+      uint32_t old_length = static_cast<uint32_t>(old_elements->length());
+      // Fill out the new array with this content and array holes.
+      for (uint32_t i = 0; i < old_length; i++) {
+        elems->set(i, old_elements->get(i), mode);
+      }
+      break;
     }
-  } else {
-    NumberDictionary* dictionary = NumberDictionary::cast(elements());
-    for (int i = 0; i < dictionary->Capacity(); i++) {
-      Object* key = dictionary->KeyAt(i);
-      if (key->IsNumber()) {
-        uint32_t entry = static_cast<uint32_t>(key->Number());
-        elems->set(entry, dictionary->ValueAt(i), mode);
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = NumberDictionary::cast(elements());
+      for (int i = 0; i < dictionary->Capacity(); i++) {
+        Object* key = dictionary->KeyAt(i);
+        if (key->IsNumber()) {
+          uint32_t entry = static_cast<uint32_t>(key->Number());
+          elems->set(entry, dictionary->ValueAt(i), mode);
+        }
       }
+      break;
     }
+    default:
+      UNREACHABLE();
+      break;
   }
   set_elements(elems);
 }
 
 
 Object* JSObject::SetSlowElements(Object* len) {
+  // We should never end in here with a pixel array.
+  ASSERT(!HasPixelElements());
+
   uint32_t new_length = static_cast<uint32_t>(len->Number());
 
-  if (!HasFastElements()) {
-    if (IsJSArray()) {
-      uint32_t old_length =
-          static_cast<uint32_t>(JSArray::cast(this)->length()->Number());
-      element_dictionary()->RemoveNumberEntries(new_length, old_length),
-      JSArray::cast(this)->set_length(len);
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      // Make sure we never try to shrink dense arrays into sparse arrays.
+      ASSERT(static_cast<uint32_t>(FixedArray::cast(elements())->length()) <=
+                                   new_length);
+      Object* obj = NormalizeElements();
+      if (obj->IsFailure()) return obj;
+      
+      // Update length for JSArrays.
+      if (IsJSArray()) JSArray::cast(this)->set_length(len);
+      break;
     }
-    return this;
+    case DICTIONARY_ELEMENTS: {
+      if (IsJSArray()) {
+        uint32_t old_length =
+        static_cast<uint32_t>(JSArray::cast(this)->length()->Number());
+        element_dictionary()->RemoveNumberEntries(new_length, old_length),
+        JSArray::cast(this)->set_length(len);
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
-
-  // Make sure we never try to shrink dense arrays into sparse arrays.
-  ASSERT(static_cast<uint32_t>(FixedArray::cast(elements())->length()) <=
-                               new_length);
-  Object* obj = NormalizeElements();
-  if (obj->IsFailure()) return obj;
-
-  // Update length for JSArrays.
-  if (IsJSArray()) JSArray::cast(this)->set_length(len);
   return this;
 }
 
 
 Object* JSArray::Initialize(int capacity) {
   ASSERT(capacity >= 0);
   set_length(Smi::FromInt(0), SKIP_WRITE_BARRIER);
   FixedArray* new_elements;
   if (capacity == 0) {
     new_elements = Heap::empty_fixed_array();
   } else {
     Object* obj = Heap::AllocateFixedArrayWithHoles(capacity);
     if (obj->IsFailure()) return obj;
     new_elements = FixedArray::cast(obj);
   }
   set_elements(new_elements);
   return this;
 }
 
 
 void JSArray::Expand(int required_size) {
   Handle<JSArray> self(this);
-  Handle<FixedArray> old_backing(elements());
+  Handle<FixedArray> old_backing(FixedArray::cast(elements()));
   int old_size = old_backing->length();
   // Doubling in size would be overkill, but leave some slack to avoid
   // constantly growing.
   int new_size = required_size + (required_size >> 3);
   Handle<FixedArray> new_backing = Factory::NewFixedArray(new_size);
   // Can't use this any more now because we may have had a GC!
   for (int i = 0; i < old_size; i++) new_backing->set(i, old_backing->get(i));
   self->SetContent(*new_backing);
 }
 
 
 // Computes the new capacity when expanding the elements of a JSObject.
 static int NewElementsCapacity(int old_capacity) {
   // (old_capacity + 50%) + 16
   return old_capacity + (old_capacity >> 1) + 16;
 }
 
 
 static Object* ArrayLengthRangeError() {
   HandleScope scope;
   return Top::Throw(*Factory::NewRangeError("invalid_array_length",
                                             HandleVector<Object>(NULL, 0)));
 }
 
 
 Object* JSObject::SetElementsLength(Object* len) {
+  // We should never end in here with a pixel array.
+  ASSERT(!HasPixelElements());
+
   Object* smi_length = len->ToSmi();
   if (smi_length->IsSmi()) {
     int value = Smi::cast(smi_length)->value();
     if (value < 0) return ArrayLengthRangeError();
-    if (HasFastElements()) {
-      int old_capacity = FixedArray::cast(elements())->length();
-      if (value <= old_capacity) {
+    switch (GetElementsKind()) {
+      case FAST_ELEMENTS: {
+        int old_capacity = FixedArray::cast(elements())->length();
+        if (value <= old_capacity) {
+          if (IsJSArray()) {
+            int old_length = FastD2I(JSArray::cast(this)->length()->Number());
+            // NOTE: We may be able to optimize this by removing the
+            // last part of the elements backing storage array and
+            // setting the capacity to the new size.
+            for (int i = value; i < old_length; i++) {
+              FixedArray::cast(elements())->set_the_hole(i);
+            }
+            JSArray::cast(this)->set_length(smi_length, SKIP_WRITE_BARRIER);
+          }
+          return this;
+        }
+        int min = NewElementsCapacity(old_capacity);
+        int new_capacity = value > min ? value : min;
+        if (new_capacity <= kMaxFastElementsLength ||
+            !ShouldConvertToSlowElements(new_capacity)) {
+          Object* obj = Heap::AllocateFixedArrayWithHoles(new_capacity);
+          if (obj->IsFailure()) return obj;
+          if (IsJSArray()) JSArray::cast(this)->set_length(smi_length,
+                                                           SKIP_WRITE_BARRIER);
+          SetFastElements(FixedArray::cast(obj));
+          return this;
+        }
+        break;
+      }
+      case DICTIONARY_ELEMENTS: {
         if (IsJSArray()) {
-          int old_length = FastD2I(JSArray::cast(this)->length()->Number());
-          // NOTE: We may be able to optimize this by removing the
-          // last part of the elements backing storage array and
-          // setting the capacity to the new size.
-          for (int i = value; i < old_length; i++) {
-            FixedArray::cast(elements())->set_the_hole(i);
+          if (value == 0) {
+            // If the length of a slow array is reset to zero, we clear
+            // the array and flush backing storage. This has the added
+            // benefit that the array returns to fast mode.
+            initialize_elements();
+          } else {
+            // Remove deleted elements.
+            uint32_t old_length =
+            static_cast<uint32_t>(JSArray::cast(this)->length()->Number());
+            element_dictionary()->RemoveNumberEntries(value, old_length);
           }
           JSArray::cast(this)->set_length(smi_length, SKIP_WRITE_BARRIER);
         }
         return this;
       }
-      int min = NewElementsCapacity(old_capacity);
-      int new_capacity = value > min ? value : min;
-      if (new_capacity <= kMaxFastElementsLength ||
-          !ShouldConvertToSlowElements(new_capacity)) {
-        Object* obj = Heap::AllocateFixedArrayWithHoles(new_capacity);
-        if (obj->IsFailure()) return obj;
-        if (IsJSArray()) JSArray::cast(this)->set_length(smi_length,
-                                                         SKIP_WRITE_BARRIER);
-        SetFastElements(FixedArray::cast(obj));
-        return this;
-      }
-    } else {
-      if (IsJSArray()) {
-        if (value == 0) {
-          // If the length of a slow array is reset to zero, we clear
-          // the array and flush backing storage. This has the added
-          // benefit that the array returns to fast mode.
-          initialize_elements();
-        } else {
-          // Remove deleted elements.
-          uint32_t old_length =
-              static_cast<uint32_t>(JSArray::cast(this)->length()->Number());
-          element_dictionary()->RemoveNumberEntries(value, old_length);
-        }
-        JSArray::cast(this)->set_length(smi_length, SKIP_WRITE_BARRIER);
-      }
-      return this;
+      default:
+        UNREACHABLE();
+        break;
     }
   }
 
   // General slow case.
   if (len->IsNumber()) {
     uint32_t length;
     if (Array::IndexFromObject(len, &length)) {
       return SetSlowElements(len);
     } else {
       return ArrayLengthRangeError();
     }
   }
 
   // len is not a number so make the array size one and
   // set only element to len.
   Object* obj = Heap::AllocateFixedArray(1);
   if (obj->IsFailure()) return obj;
   FixedArray::cast(obj)->set(0, len);
   if (IsJSArray()) JSArray::cast(this)->set_length(Smi::FromInt(1),
                                                    SKIP_WRITE_BARRIER);
   set_elements(FixedArray::cast(obj));
   return this;
 }
 
 
 bool JSObject::HasElementPostInterceptor(JSObject* receiver, uint32_t index) {
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
-        static_cast<uint32_t>(
-            Smi::cast(JSArray::cast(this)->length())->value()) :
-        static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    if ((index < length) &&
-        !FixedArray::cast(elements())->get(index)->IsTheHole()) {
-      return true;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
+          static_cast<uint32_t>
+              (Smi::cast(JSArray::cast(this)->length())->value()) :
+          static_cast<uint32_t>(FixedArray::cast(elements())->length());
+      if ((index < length) &&
+          !FixedArray::cast(elements())->get(index)->IsTheHole()) {
+        return true;
+      }
+      break;
     }
-  } else {
-    if (element_dictionary()->FindEntry(index)
-        != NumberDictionary::kNotFound) {
-      return true;
+    case PIXEL_ELEMENTS: {
+      // TODO(iposva): Add testcase.
+      PixelArray* pixels = PixelArray::cast(elements());
+      if (index < static_cast<uint32_t>(pixels->length())) {
+        return true;
+      }
+      break;
     }
+    case DICTIONARY_ELEMENTS: {
+      if (element_dictionary()->FindEntry(index)
+          != NumberDictionary::kNotFound) {
+        return true;
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
 
   // Handle [] on String objects.
   if (this->IsStringObjectWithCharacterAt(index)) return true;
 
   Object* pt = GetPrototype();
   if (pt == Heap::null_value()) return false;
   return JSObject::cast(pt)->HasElementWithReceiver(receiver, index);
 }
 
@@ skipping 46 matching lines @@
   }
 
   // Check for lookup interceptor
   if (HasIndexedInterceptor()) {
     return HasElementWithInterceptor(this, index);
   }
 
   // Handle [] on String objects.
   if (this->IsStringObjectWithCharacterAt(index)) return true;
 
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
-        static_cast<uint32_t>(
-            Smi::cast(JSArray::cast(this)->length())->value()) :
-        static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    return (index < length) &&
-           !FixedArray::cast(elements())->get(index)->IsTheHole();
-  } else {
-    return element_dictionary()->FindEntry(index)
-        != NumberDictionary::kNotFound;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
+          static_cast<uint32_t>
+              (Smi::cast(JSArray::cast(this)->length())->value()) :
+          static_cast<uint32_t>(FixedArray::cast(elements())->length());
+      return (index < length) &&
+          !FixedArray::cast(elements())->get(index)->IsTheHole();
+    }
+    case PIXEL_ELEMENTS: {
+      PixelArray* pixels = PixelArray::cast(elements());
+      return (index < static_cast<uint32_t>(pixels->length()));
+    }
+    case DICTIONARY_ELEMENTS: {
+      return element_dictionary()->FindEntry(index)
+          != NumberDictionary::kNotFound;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
+  UNREACHABLE();
+  return Heap::null_value();
 }
 
 
 bool JSObject::HasElementWithReceiver(JSObject* receiver, uint32_t index) {
   // Check access rights if needed.
   if (IsAccessCheckNeeded() &&
       !Top::MayIndexedAccess(this, index, v8::ACCESS_HAS)) {
     Top::ReportFailedAccessCheck(this, v8::ACCESS_HAS);
     return false;
   }
 
   // Check for lookup interceptor
   if (HasIndexedInterceptor()) {
     return HasElementWithInterceptor(receiver, index);
   }
 
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
-        static_cast<uint32_t>(
-            Smi::cast(JSArray::cast(this)->length())->value()) :
-        static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    if ((index < length) &&
-        !FixedArray::cast(elements())->get(index)->IsTheHole()) return true;
-  } else {
-    if (element_dictionary()->FindEntry(index)
-        != NumberDictionary::kNotFound) {
-      return true;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
+          static_cast<uint32_t>
+              (Smi::cast(JSArray::cast(this)->length())->value()) :
+          static_cast<uint32_t>(FixedArray::cast(elements())->length());
+      if ((index < length) &&
+          !FixedArray::cast(elements())->get(index)->IsTheHole()) return true;
+      break;
     }
+    case PIXEL_ELEMENTS: {
+      PixelArray* pixels = PixelArray::cast(elements());
+      if (index < static_cast<uint32_t>(pixels->length())) {
+        return true;
+      }
+      break;
+    }
+    case DICTIONARY_ELEMENTS: {
+      if (element_dictionary()->FindEntry(index)
+          != NumberDictionary::kNotFound) {
+        return true;
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
 
   // Handle [] on String objects.
   if (this->IsStringObjectWithCharacterAt(index)) return true;
 
   Object* pt = GetPrototype();
   if (pt == Heap::null_value()) return false;
   return JSObject::cast(pt)->HasElementWithReceiver(receiver, index);
 }
 
@@ skipping 75 matching lines @@
       if (IsJSArray()) JSArray::cast(this)->set_length(Smi::FromInt(index + 1),
                                                        SKIP_WRITE_BARRIER);
       FixedArray::cast(elements())->set(index, value);
       return value;
     }
   }
 
   // Otherwise default to slow case.
   Object* obj = NormalizeElements();
   if (obj->IsFailure()) return obj;
-  ASSERT(!HasFastElements());
+  ASSERT(HasDictionaryElements());
   return SetElement(index, value);
 }
 
 Object* JSObject::SetElement(uint32_t index, Object* value) {
   // Check access rights if needed.
   if (IsAccessCheckNeeded() &&
       !Top::MayIndexedAccess(this, index, v8::ACCESS_SET)) {
     Top::ReportFailedAccessCheck(this, v8::ACCESS_SET);
     return value;
   }
 
   if (IsJSGlobalProxy()) {
     Object* proto = GetPrototype();
     if (proto->IsNull()) return value;
     ASSERT(proto->IsJSGlobalObject());
     return JSObject::cast(proto)->SetElement(index, value);
   }
 
   // Check for lookup interceptor
   if (HasIndexedInterceptor()) {
     return SetElementWithInterceptor(index, value);
   }
 
   return SetElementWithoutInterceptor(index, value);
 }
 
 
 Object* JSObject::SetElementWithoutInterceptor(uint32_t index, Object* value) {
-  // Fast case.
-  if (HasFastElements()) return SetFastElement(index, value);
-
-  // Dictionary case.
-  ASSERT(!HasFastElements());
-
-  // Insert element in the dictionary.
-  FixedArray* elms = FixedArray::cast(elements());
-  NumberDictionary* dictionary = NumberDictionary::cast(elms);
-
-  int entry = dictionary->FindEntry(index);
-  if (entry != NumberDictionary::kNotFound) {
-    Object* element = dictionary->ValueAt(entry);
-    PropertyDetails details = dictionary->DetailsAt(entry);
-    if (details.type() == CALLBACKS) {
-      // Only accessors allowed as elements.
-      FixedArray* structure = FixedArray::cast(element);
-      if (structure->get(kSetterIndex)->IsJSFunction()) {
-        JSFunction* setter = JSFunction::cast(structure->get(kSetterIndex));
-        return SetPropertyWithDefinedSetter(setter, value);
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS:
+      // Fast case.
+      return SetFastElement(index, value);
+    case PIXEL_ELEMENTS: {
+      PixelArray* pixels = PixelArray::cast(elements());
+      return pixels->SetValue(index, value);
+    }
+    case DICTIONARY_ELEMENTS: {
+      // Insert element in the dictionary.
+      FixedArray* elms = FixedArray::cast(elements());
+      NumberDictionary* dictionary = NumberDictionary::cast(elms);
+      
+      int entry = dictionary->FindEntry(index);
+      if (entry != NumberDictionary::kNotFound) {
+        Object* element = dictionary->ValueAt(entry);
+        PropertyDetails details = dictionary->DetailsAt(entry);
+        if (details.type() == CALLBACKS) {
+          // Only accessors allowed as elements.
+          FixedArray* structure = FixedArray::cast(element);
+          if (structure->get(kSetterIndex)->IsJSFunction()) {
+            JSFunction* setter = JSFunction::cast(structure->get(kSetterIndex));
+            return SetPropertyWithDefinedSetter(setter, value);
+          } else {
+            Handle<Object> self(this);
+            Handle<Object> key(Factory::NewNumberFromUint(index));
+            Handle<Object> args[2] = { key, self };
+            return Top::Throw(*Factory::NewTypeError("no_setter_in_callback",
+                                                     HandleVector(args, 2)));
+          }
+        } else {
+          dictionary->UpdateMaxNumberKey(index);
+          dictionary->ValueAtPut(entry, value);
+        }
       } else {
-        Handle<Object> self(this);
-        Handle<Object> key(Factory::NewNumberFromUint(index));
-        Handle<Object> args[2] = { key, self };
-        return Top::Throw(*Factory::NewTypeError("no_setter_in_callback",
-                                                 HandleVector(args, 2)));
+        // Index not already used. Look for an accessor in the prototype chain.
+        if (!IsJSArray()) {
+          Object* setter = LookupCallbackSetterInPrototypes(index);
+          if (setter->IsJSFunction()) {
+            return SetPropertyWithDefinedSetter(JSFunction::cast(setter),
+                                                value);
+          }
+        }
+        Object* result = dictionary->AtNumberPut(index, value);
+        if (result->IsFailure()) return result;
+        if (elms != FixedArray::cast(result)) {
+          set_elements(FixedArray::cast(result));
+        }
       }
-    } else {
-      dictionary->UpdateMaxNumberKey(index);
-      dictionary->ValueAtPut(entry, value);
+      
+      // Update the array length if this JSObject is an array.
+      if (IsJSArray()) {
+        JSArray* array = JSArray::cast(this);
+        Object* return_value = array->JSArrayUpdateLengthFromIndex(index,
+                                                                   value);
+        if (return_value->IsFailure()) return return_value;
+      }
+      
+      // Attempt to put this object back in fast case.
+      if (ShouldConvertToFastElements()) {
+        uint32_t new_length = 0;
+        if (IsJSArray()) {
+          CHECK(Array::IndexFromObject(JSArray::cast(this)->length(),
+                                       &new_length));
+          JSArray::cast(this)->set_length(Smi::FromInt(new_length));
+        } else {
+          new_length = NumberDictionary::cast(elements())->max_number_key() + 1;
+        }
+        Object* obj = Heap::AllocateFixedArrayWithHoles(new_length);
+        if (obj->IsFailure()) return obj;
+        SetFastElements(FixedArray::cast(obj));
+#ifdef DEBUG
+        if (FLAG_trace_normalization) {
+          PrintF("Object elements are fast case again:\n");
+          Print();
+        }
+#endif
+      }
+      
+      return value;
     }
-  } else {
-    // Index not already used. Look for an accessor in the prototype chain.
-    if (!IsJSArray()) {
-      Object* setter = LookupCallbackSetterInPrototypes(index);
-      if (setter->IsJSFunction()) {
-        return SetPropertyWithDefinedSetter(JSFunction::cast(setter), value);
-      }
-    }
-    Object* result = dictionary->AtNumberPut(index, value);
-    if (result->IsFailure()) return result;
-    if (elms != FixedArray::cast(result)) {
-      set_elements(FixedArray::cast(result));
-    }
+    default:
+      UNREACHABLE();
+      break;
   }
-
-  // Update the array length if this JSObject is an array.
-  if (IsJSArray()) {
-    JSArray* array = JSArray::cast(this);
-    Object* return_value = array->JSArrayUpdateLengthFromIndex(index, value);
-    if (return_value->IsFailure()) return return_value;
-  }
-
-  // Attempt to put this object back in fast case.
-  if (ShouldConvertToFastElements()) {
-    uint32_t new_length = 0;
-    if (IsJSArray()) {
-      CHECK(Array::IndexFromObject(JSArray::cast(this)->length(), &new_length));
-      JSArray::cast(this)->set_length(Smi::FromInt(new_length));
-    } else {
-      new_length = NumberDictionary::cast(elements())->max_number_key() + 1;
-    }
-    Object* obj = Heap::AllocateFixedArrayWithHoles(new_length);
-    if (obj->IsFailure()) return obj;
-    SetFastElements(FixedArray::cast(obj));
-#ifdef DEBUG
-    if (FLAG_trace_normalization) {
-      PrintF("Object elements are fast case again:\n");
-      Print();
-    }
-#endif
-  }
-
-  return value;
+  // All possible cases have been handled above. Add a return to avoid the
+  // complaints from the compiler.
+  UNREACHABLE();
+  return Heap::null_value();
 }
 
 
 Object* JSArray::JSArrayUpdateLengthFromIndex(uint32_t index, Object* value) {
   uint32_t old_len = 0;
   CHECK(Array::IndexFromObject(length(), &old_len));
   // Check to see if we need to update the length. For now, we make
   // sure that the length stays within 32-bits (unsigned).
   if (index >= old_len && index != 0xffffffff) {
     Object* len =
         Heap::NumberFromDouble(static_cast<double>(index) + 1);
     if (len->IsFailure()) return len;
     set_length(len);
   }
   return value;
 }
 
 
 Object* JSObject::GetElementPostInterceptor(JSObject* receiver,
                                             uint32_t index) {
   // Get element works for both JSObject and JSArray since
   // JSArray::length cannot change.
-  if (HasFastElements()) {
-    FixedArray* elms = FixedArray::cast(elements());
-    if (index < static_cast<uint32_t>(elms->length())) {
-      Object* value = elms->get(index);
-      if (!value->IsTheHole()) return value;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      FixedArray* elms = FixedArray::cast(elements());
+      if (index < static_cast<uint32_t>(elms->length())) {
+        Object* value = elms->get(index);
+        if (!value->IsTheHole()) return value;
+      }
+      break;
     }
-  } else {
-    NumberDictionary* dictionary = element_dictionary();
-    int entry = dictionary->FindEntry(index);
-    if (entry != NumberDictionary::kNotFound) {
-      Object* element = dictionary->ValueAt(entry);
-      PropertyDetails details = dictionary->DetailsAt(entry);
-      if (details.type() == CALLBACKS) {
-        // Only accessors allowed as elements.
-        FixedArray* structure = FixedArray::cast(element);
-        Object* getter = structure->get(kGetterIndex);
-        if (getter->IsJSFunction()) {
-          return GetPropertyWithDefinedGetter(receiver,
-                                              JSFunction::cast(getter));
-        } else {
-          // Getter is not a function.
-          return Heap::undefined_value();
+    case PIXEL_ELEMENTS: {
+      // TODO(iposva): Add testcase and implement.
+      UNIMPLEMENTED();
+      break;
+    }
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = element_dictionary();
+      int entry = dictionary->FindEntry(index);
+      if (entry != NumberDictionary::kNotFound) {
+        Object* element = dictionary->ValueAt(entry);
+        PropertyDetails details = dictionary->DetailsAt(entry);
+        if (details.type() == CALLBACKS) {
+          // Only accessors allowed as elements.
+          FixedArray* structure = FixedArray::cast(element);
+          Object* getter = structure->get(kGetterIndex);
+          if (getter->IsJSFunction()) {
+            return GetPropertyWithDefinedGetter(receiver,
+                                                JSFunction::cast(getter));
+          } else {
+            // Getter is not a function.
+            return Heap::undefined_value();
+          }
         }
+        return element;
       }
-      return element;
+      break;
     }
+    default:
+      UNREACHABLE();
+      break;
   }
 
   // Continue searching via the prototype chain.
   Object* pt = GetPrototype();
   if (pt == Heap::null_value()) return Heap::undefined_value();
   return pt->GetElementWithReceiver(receiver, index);
 }
 
 
 Object* JSObject::GetElementWithInterceptor(JSObject* receiver,
@@ skipping 38 matching lines @@
     Top::ReportFailedAccessCheck(this, v8::ACCESS_GET);
     return Heap::undefined_value();
   }
 
   if (HasIndexedInterceptor()) {
     return GetElementWithInterceptor(receiver, index);
   }
 
   // Get element works for both JSObject and JSArray since
   // JSArray::length cannot change.
-  if (HasFastElements()) {
-    FixedArray* elms = FixedArray::cast(elements());
-    if (index < static_cast<uint32_t>(elms->length())) {
-      Object* value = elms->get(index);
-      if (!value->IsTheHole()) return value;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      FixedArray* elms = FixedArray::cast(elements());
+      if (index < static_cast<uint32_t>(elms->length())) {
+        Object* value = elms->get(index);
+        if (!value->IsTheHole()) return value;
+      }
+      break;
     }
-  } else {
-    NumberDictionary* dictionary = element_dictionary();
-    int entry = dictionary->FindEntry(index);
-    if (entry != NumberDictionary::kNotFound) {
-      Object* element = dictionary->ValueAt(entry);
-      PropertyDetails details = dictionary->DetailsAt(entry);
-      if (details.type() == CALLBACKS) {
-        // Only accessors allowed as elements.
-        FixedArray* structure = FixedArray::cast(element);
-        Object* getter = structure->get(kGetterIndex);
-        if (getter->IsJSFunction()) {
-          return GetPropertyWithDefinedGetter(receiver,
-                                              JSFunction::cast(getter));
-        } else {
-          // Getter is not a function.
-          return Heap::undefined_value();
+    case PIXEL_ELEMENTS: {
+      PixelArray* pixels = PixelArray::cast(elements());
+      if (index < static_cast<uint32_t>(pixels->length())) {
+        uint8_t value = pixels->get(index);
+        return Smi::FromInt(value);
+      }
+      break;
+    }
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = element_dictionary();
+      int entry = dictionary->FindEntry(index);
+      if (entry != NumberDictionary::kNotFound) {
+        Object* element = dictionary->ValueAt(entry);
+        PropertyDetails details = dictionary->DetailsAt(entry);
+        if (details.type() == CALLBACKS) {
+          // Only accessors allowed as elements.
+          FixedArray* structure = FixedArray::cast(element);
+          Object* getter = structure->get(kGetterIndex);
+          if (getter->IsJSFunction()) {
+            return GetPropertyWithDefinedGetter(receiver,
+                                                JSFunction::cast(getter));
+          } else {
+            // Getter is not a function.
+            return Heap::undefined_value();
+          }
         }
+        return element;
       }
-      return element;
+      break;
     }
   }
 
   Object* pt = GetPrototype();
   if (pt == Heap::null_value()) return Heap::undefined_value();
   return pt->GetElementWithReceiver(receiver, index);
 }
 
 
 bool JSObject::HasDenseElements() {
   int capacity = 0;
   int number_of_elements = 0;
 
-  if (HasFastElements()) {
-    FixedArray* elms = FixedArray::cast(elements());
-    capacity = elms->length();
-    for (int i = 0; i < capacity; i++) {
-      if (!elms->get(i)->IsTheHole()) number_of_elements++;
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      FixedArray* elms = FixedArray::cast(elements());
+      capacity = elms->length();
+      for (int i = 0; i < capacity; i++) {
+        if (!elms->get(i)->IsTheHole()) number_of_elements++;
+      }
+      break;
     }
-  } else {
-    NumberDictionary* dictionary = NumberDictionary::cast(elements());
-    capacity = dictionary->Capacity();
-    number_of_elements = dictionary->NumberOfElements();
+    case PIXEL_ELEMENTS: {
+      return true;
+    }
+    case DICTIONARY_ELEMENTS: {
+      NumberDictionary* dictionary = NumberDictionary::cast(elements());
+      capacity = dictionary->Capacity();
+      number_of_elements = dictionary->NumberOfElements();
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
 
   if (capacity == 0) return true;
   return (number_of_elements > (capacity / 2));
 }
 
 
 bool JSObject::ShouldConvertToSlowElements(int new_capacity) {
   ASSERT(HasFastElements());
   // Keep the array in fast case if the current backing storage is
   // almost filled and if the new capacity is no more than twice the
   // old capacity.
   int elements_length = FixedArray::cast(elements())->length();
   return !HasDenseElements() || ((new_capacity / 2) > elements_length);
 }
 
 
 bool JSObject::ShouldConvertToFastElements() {
-  ASSERT(!HasFastElements());
+  ASSERT(HasDictionaryElements());
   NumberDictionary* dictionary = NumberDictionary::cast(elements());
   // If the elements are sparse, we should not go back to fast case.
   if (!HasDenseElements()) return false;
   // If an element has been added at a very high index in the elements
   // dictionary, we cannot go back to fast case.
   if (dictionary->requires_slow_elements()) return false;
   // An object requiring access checks is never allowed to have fast
   // elements.  If it had fast elements we would skip security checks.
   if (IsAccessCheckNeeded()) return false;
   // If the dictionary backing storage takes up roughly half as much
@@ skipping 233 matching lines @@
   // Check access rights if needed.
   if (IsAccessCheckNeeded() &&
       !Top::MayIndexedAccess(this, index, v8::ACCESS_HAS)) {
     Top::ReportFailedAccessCheck(this, v8::ACCESS_HAS);
     return false;
   }
 
   // Handle [] on String objects.
   if (this->IsStringObjectWithCharacterAt(index)) return true;
 
-  if (HasFastElements()) {
-    uint32_t length = IsJSArray() ?
-        static_cast<uint32_t>(
-            Smi::cast(JSArray::cast(this)->length())->value()) :
-        static_cast<uint32_t>(FixedArray::cast(elements())->length());
-    return (index < length) &&
-        !FixedArray::cast(elements())->get(index)->IsTheHole();
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      uint32_t length = IsJSArray() ?
+          static_cast<uint32_t>(
+              Smi::cast(JSArray::cast(this)->length())->value()) :
+          static_cast<uint32_t>(FixedArray::cast(elements())->length());
+      return (index < length) &&
+          !FixedArray::cast(elements())->get(index)->IsTheHole();
+    }
+    case PIXEL_ELEMENTS: {
+      PixelArray* pixels = PixelArray::cast(elements());
+      return index < static_cast<uint32_t>(pixels->length());
+    }
+    case DICTIONARY_ELEMENTS: {
+      return element_dictionary()->FindEntry(index)
+          != NumberDictionary::kNotFound;
+    }
+    default:
+      UNREACHABLE();
+      break;
   }
-  return element_dictionary()->FindEntry(index)
-      != NumberDictionary::kNotFound;
+  // All possibilities have been handled above already.
+  UNREACHABLE();
+  return Heap::null_value();
 }
 
 
 bool JSObject::HasRealNamedCallbackProperty(String* key) {
   // Check access rights if needed.
   if (IsAccessCheckNeeded() &&
       !Top::MayNamedAccess(this, key, v8::ACCESS_HAS)) {
     Top::ReportFailedAccessCheck(this, v8::ACCESS_HAS);
     return false;
   }
@@ skipping 162 matching lines @@
 
 
 int JSObject::NumberOfEnumElements() {
   return NumberOfLocalElements(static_cast<PropertyAttributes>(DONT_ENUM));
 }
 
 
 int JSObject::GetLocalElementKeys(FixedArray* storage,
                                   PropertyAttributes filter) {
   int counter = 0;
-  if (HasFastElements()) {
-    int length = IsJSArray()
-        ? Smi::cast(JSArray::cast(this)->length())->value()
-        : FixedArray::cast(elements())->length();
-    for (int i = 0; i < length; i++) {
-      if (!FixedArray::cast(elements())->get(i)->IsTheHole()) {
-        if (storage) {
-          storage->set(counter, Smi::FromInt(i), SKIP_WRITE_BARRIER);
+  switch (GetElementsKind()) {
+    case FAST_ELEMENTS: {
+      int length = IsJSArray() ?
+          Smi::cast(JSArray::cast(this)->length())->value() :
+          FixedArray::cast(elements())->length();
+      for (int i = 0; i < length; i++) {
+        if (!FixedArray::cast(elements())->get(i)->IsTheHole()) {
+          if (storage != NULL) {
+            storage->set(counter, Smi::FromInt(i), SKIP_WRITE_BARRIER);
+          }
+          counter++;
+        }
+      }
+      ASSERT(!storage || storage->length() >= counter);
+      break;
+    }
+    case PIXEL_ELEMENTS: {
+      int length = PixelArray::cast(elements())->length();
+      while (counter < length) {
+        if (storage != NULL) {
+          storage->set(counter, Smi::FromInt(counter), SKIP_WRITE_BARRIER);
         }
         counter++;
       }
+      ASSERT(!storage || storage->length() >= counter);
+      break;
     }
-    ASSERT(!storage || storage->length() >= counter);
-  } else {
-    if (storage) {
-      element_dictionary()->CopyKeysTo(storage, filter);
+    case DICTIONARY_ELEMENTS: {
+      if (storage != NULL) {
+        element_dictionary()->CopyKeysTo(storage, filter);
+      }
+      counter = element_dictionary()->NumberOfElementsFilterAttributes(filter);
+      break;
     }
-    counter = element_dictionary()->NumberOfElementsFilterAttributes(filter);
+    default:
+      UNREACHABLE();
+      break;
   }
 
   if (this->IsJSValue()) {
     Object* val = JSValue::cast(this)->value();
     if (val->IsString()) {
       String* str = String::cast(val);
       if (storage) {
         for (int i = 0; i < str->length(); i++) {
           storage->set(counter + i, Smi::FromInt(i), SKIP_WRITE_BARRIER);
         }
@@ skipping 438 matching lines @@
 
 template
 int Dictionary<NumberDictionaryShape, uint32_t>::NumberOfEnumElements();
 
 template
 int Dictionary<StringDictionaryShape, String*>::NumberOfEnumElements();
 
 // Collates undefined and unexisting elements below limit from position
 // zero of the elements. The object stays in Dictionary mode.
 Object* JSObject::PrepareSlowElementsForSort(uint32_t limit) {
-  ASSERT(!HasFastElements());
+  ASSERT(HasDictionaryElements());
   // Must stay in dictionary mode, either because of requires_slow_elements,
   // or because we are not going to sort (and therefore compact) all of the
   // elements.
   NumberDictionary* dict = element_dictionary();
   HeapNumber* result_double = NULL;
   if (limit > static_cast<uint32_t>(Smi::kMaxValue)) {
     // Allocate space for result before we start mutating the object.
     Object* new_double = Heap::AllocateHeapNumber(0.0);
     if (new_double->IsFailure()) return new_double;
     result_double = HeapNumber::cast(new_double);
@@ skipping 53 matching lines @@
   result_double->set_value(static_cast<double>(result));
   return result_double;
 }
 
 
 // Collects all defined (non-hole) and non-undefined (array) elements at
 // the start of the elements array.
 // If the object is in dictionary mode, it is converted to fast elements
 // mode.
 Object* JSObject::PrepareElementsForSort(uint32_t limit) {
-  if (!HasFastElements()) {
+  ASSERT(!HasPixelElements());
+
+  if (HasDictionaryElements()) {
     // Convert to fast elements containing only the existing properties.
     // Ordering is irrelevant, since we are going to sort anyway.
     NumberDictionary* dict = element_dictionary();
     if (IsJSArray() || dict->requires_slow_elements() ||
         dict->max_number_key() >= limit) {
       return PrepareSlowElementsForSort(limit);
     }
     // Convert to fast elements.
 
     PretenureFlag tenure = Heap::InNewSpace(this) ? NOT_TENURED: TENURED;
     Object* new_array =
         Heap::AllocateFixedArray(dict->NumberOfElements(), tenure);
     if (new_array->IsFailure()) {
       return new_array;
     }
     FixedArray* fast_elements = FixedArray::cast(new_array);
     dict->CopyValuesTo(fast_elements);
     set_elements(fast_elements);
   }
   ASSERT(HasFastElements());
 
   // Collect holes at the end, undefined before that and the rest at the
   // start, and return the number of non-hole, non-undefined values.
 
-  FixedArray* elements = this->elements();
+  FixedArray* elements = FixedArray::cast(this->elements());
   uint32_t elements_length = static_cast<uint32_t>(elements->length());
   if (limit > elements_length) {
     limit = elements_length ;
   }
   if (limit == 0) {
     return Smi::FromInt(0);
   }
 
   HeapNumber* result_double = NULL;
   if (limit > static_cast<uint32_t>(Smi::kMaxValue)) {
@@ skipping 49 matching lines @@
 
   if (result <= static_cast<uint32_t>(Smi::kMaxValue)) {
     return Smi::FromInt(static_cast<int>(result));
   }
   ASSERT_NE(NULL, result_double);
   result_double->set_value(static_cast<double>(result));
   return result_double;
 }
 
 
+Object* PixelArray::SetValue(uint32_t index, Object* value) {
+  uint8_t clamped_value = 0;
+  if (index < static_cast<uint32_t>(length())) {
+    int int_value = 0;
+    if (value->IsSmi()) {
+      int_value = Smi::cast(value)->value();
+    } else if (value->IsHeapNumber()) {
+      static const DoubleRepresentation nan(OS::nan_value());
+      DoubleRepresentation double_value = HeapNumber::cast(value)->value();
+      if (nan.bits != double_value.bits) {
+        int_value = static_cast<int>(double_value.value + 0.5);
+      } else {
+        // NaN clamps to zero.
+        int_value = 0;
+      }
+    } else if (value->IsUndefined()) {
+      int_value = 0;
+    } else {
+      // All other types have been converted to a number type further up in the
+      // call chain.
+      UNREACHABLE();
+    }
+    if (int_value < 0) {
+      clamped_value = 0;
+    } else if (int_value > 255) {
+      clamped_value = 255;
+    } else {
+      clamped_value = static_cast<uint8_t>(int_value);
+    }
+    set(index, clamped_value);
+  }
+  return Smi::FromInt(clamped_value);
+}
+
+
 Object* GlobalObject::GetPropertyCell(LookupResult* result) {
   ASSERT(!HasFastProperties());
   Object* value = property_dictionary()->ValueAt(result->GetDictionaryEntry());
   ASSERT(value->IsJSGlobalPropertyCell());
   return value;
 }
 
 
 Object* GlobalObject::EnsurePropertyCell(String* name) {
   ASSERT(!HasFastProperties());
@@ skipping 896 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal