text: // Copyright 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
  //       with the distribution.
  //     * Neither the name of Google Inc. nor the names of its
  //       contributors may be used to endorse or promote products derived
  //       from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "v8.h"
  
  #include "accessors.h"
  #include "api.h"
  #include "arguments.h"
  #include "bootstrapper.h"
  #include "codegen.h"
  #include "compiler.h"
  #include "debug.h"
  #include "execution.h"
  #include "global-handles.h"
  #include "natives.h"
  #include "runtime.h"
  #include "stub-cache.h"
  
  namespace v8 {
  namespace internal {
  
  
  v8::ImplementationUtilities::HandleScopeData HandleScope::current_ =
      { -1, NULL, NULL };
  
  
  int HandleScope::NumberOfHandles() {
    int n = HandleScopeImplementer::instance()->blocks()->length();
    if (n == 0) return 0;
    return ((n - 1) * kHandleBlockSize) + static_cast<int>(
        (current_.next - HandleScopeImplementer::instance()->blocks()->last()));
  }
  
  
  Object** HandleScope::Extend() {
    Object** result = current_.next;
  
    ASSERT(result == current_.limit);
    // Make sure there's at least one scope on the stack and that the
    // top of the scope stack isn't a barrier.
    if (current_.extensions < 0) {
      Utils::ReportApiFailure("v8::HandleScope::CreateHandle()",
                              "Cannot create a handle without a HandleScope");
      return NULL;
    }
    HandleScopeImplementer* impl = HandleScopeImplementer::instance();
    // If there's more room in the last block, we use that. This is used
    // for fast creation of scopes after scope barriers.
    if (!impl->blocks()->is_empty()) {
      Object** limit = &impl->blocks()->last()[kHandleBlockSize];
      if (current_.limit != limit) {
        current_.limit = limit;
      }
    }
  
    // If we still haven't found a slot for the handle, we extend the
    // current handle scope by allocating a new handle block.
    if (result == current_.limit) {
      // If there's a spare block, use it for growing the current scope.
      result = impl->GetSpareOrNewBlock();
      // Add the extension to the global list of blocks, but count the
      // extension as part of the current scope.
      impl->blocks()->Add(result);
      current_.extensions++;
      current_.limit = &result[kHandleBlockSize];
    }
  
    return result;
  }
  
  
  void HandleScope::DeleteExtensions() {
    ASSERT(current_.extensions != 0);
    HandleScopeImplementer::instance()->DeleteExtensions(current_.extensions);
  }
  
  
  void HandleScope::ZapRange(Object** start, Object** end) {
    if (start == NULL) return;
    for (Object** p = start; p < end; p++) {
      *reinterpret_cast<Address*>(p) = v8::internal::kHandleZapValue;
    }
  }
  
  
  Address HandleScope::current_extensions_address() {
    return reinterpret_cast<Address>(&current_.extensions);
  }
  
  
  Address HandleScope::current_next_address() {
    return reinterpret_cast<Address>(&current_.next);
  }
  
  
  Address HandleScope::current_limit_address() {
    return reinterpret_cast<Address>(&current_.limit);
  }
  
  
  Handle<FixedArray> AddKeysFromJSArray(Handle<FixedArray> content,
                                        Handle<JSArray> array) {
    CALL_HEAP_FUNCTION(content->AddKeysFromJSArray(*array), FixedArray);
  }
  
  
  Handle<FixedArray> UnionOfKeys(Handle<FixedArray> first,
                                 Handle<FixedArray> second) {
    CALL_HEAP_FUNCTION(first->UnionOfKeys(*second), FixedArray);
  }
  
  
  Handle<JSGlobalProxy> ReinitializeJSGlobalProxy(
      Handle<JSFunction> constructor,
      Handle<JSGlobalProxy> global) {
    CALL_HEAP_FUNCTION(Heap::ReinitializeJSGlobalProxy(*constructor, *global),
                       JSGlobalProxy);
  }
  
  
  void SetExpectedNofProperties(Handle<JSFunction> func, int nof) {
    func->shared()->set_expected_nof_properties(nof);
    if (func->has_initial_map()) {
      Handle<Map> new_initial_map =
          Factory::CopyMapDropTransitions(Handle<Map>(func->initial_map()));
      new_initial_map->set_unused_property_fields(nof);
      func->set_initial_map(*new_initial_map);
    }
  }
  
  
  void SetPrototypeProperty(Handle<JSFunction> func, Handle<JSObject> value) {
    CALL_HEAP_FUNCTION_VOID(func->SetPrototype(*value));
  }
  
  
  static int ExpectedNofPropertiesFromEstimate(int estimate) {
    // TODO(1231235): We need dynamic feedback to estimate the number
    // of expected properties in an object. The static hack below
    // is barely a solution.
    if (estimate == 0) return 4;
    return estimate + 2;
  }
  
  
  void SetExpectedNofPropertiesFromEstimate(Handle<SharedFunctionInfo> shared,
                                            int estimate) {
    shared->set_expected_nof_properties(
        ExpectedNofPropertiesFromEstimate(estimate));
  }
  
  
  void NormalizeProperties(Handle<JSObject> object,
                           PropertyNormalizationMode mode,
                           int expected_additional_properties) {
    CALL_HEAP_FUNCTION_VOID(object->NormalizeProperties(
        mode,
        expected_additional_properties));
  }
  
  
  void NormalizeElements(Handle<JSObject> object) {
    CALL_HEAP_FUNCTION_VOID(object->NormalizeElements());
  }
  
  
  void TransformToFastProperties(Handle<JSObject> object,
                                 int unused_property_fields) {
    CALL_HEAP_FUNCTION_VOID(
        object->TransformToFastProperties(unused_property_fields));
  }
  
  
  void FlattenString(Handle<String> string) {
    CALL_HEAP_FUNCTION_VOID(string->TryFlatten());
    ASSERT(string->IsFlat());
  }
  
  
  Handle<Object> SetPrototype(Handle<JSFunction> function,
                              Handle<Object> prototype) {
    CALL_HEAP_FUNCTION(Accessors::FunctionSetPrototype(*function,
                                                       *prototype,
                                                       NULL),
                       Object);
  }
  
  
  Handle<Object> SetProperty(Handle<JSObject> object,
                             Handle<String> key,
                             Handle<Object> value,
                             PropertyAttributes attributes) {
    CALL_HEAP_FUNCTION(object->SetProperty(*key, *value, attributes), Object);
  }
  
  
  Handle<Object> SetProperty(Handle<Object> object,
                             Handle<Object> key,
                             Handle<Object> value,
                             PropertyAttributes attributes) {
    CALL_HEAP_FUNCTION(
        Runtime::SetObjectProperty(object, key, value, attributes), Object);
  }
  
  
  Handle<Object> ForceSetProperty(Handle<JSObject> object,
                                  Handle<Object> key,
                                  Handle<Object> value,
                                  PropertyAttributes attributes) {
    CALL_HEAP_FUNCTION(
        Runtime::ForceSetObjectProperty(object, key, value, attributes), Object);
  }
  
  
  Handle<Object> SetNormalizedProperty(Handle<JSObject> object,
                                       Handle<String> key,
                                       Handle<Object> value,
                                       PropertyDetails details) {
    CALL_HEAP_FUNCTION(object->SetNormalizedProperty(*key, *value, details),
                       Object);
  }
  
  
  Handle<Object> ForceDeleteProperty(Handle<JSObject> object,
                                     Handle<Object> key) {
    CALL_HEAP_FUNCTION(Runtime::ForceDeleteObjectProperty(object, key), Object);
  }
  
  
  Handle<Object> IgnoreAttributesAndSetLocalProperty(
      Handle<JSObject> object,
      Handle<String> key,
      Handle<Object> value,
      PropertyAttributes attributes) {
    CALL_HEAP_FUNCTION(object->
        IgnoreAttributesAndSetLocalProperty(*key, *value, attributes), Object);
  }
  
  
  Handle<Object> SetPropertyWithInterceptor(Handle<JSObject> object,
                                            Handle<String> key,
                                            Handle<Object> value,
                                            PropertyAttributes attributes) {
    CALL_HEAP_FUNCTION(object->SetPropertyWithInterceptor(*key,
                                                          *value,
                                                          attributes),
                       Object);
  }
  
  
  Handle<Object> GetProperty(Handle<JSObject> obj,
                             const char* name) {
    Handle<String> str = Factory::LookupAsciiSymbol(name);
    CALL_HEAP_FUNCTION(obj->GetProperty(*str), Object);
  }
  
  
  Handle<Object> GetProperty(Handle<Object> obj,
                             Handle<Object> key) {
    CALL_HEAP_FUNCTION(Runtime::GetObjectProperty(obj, key), Object);
  }
  
  
  Handle<Object> GetElement(Handle<Object> obj,
                            uint32_t index) {
    CALL_HEAP_FUNCTION(Runtime::GetElement(obj, index), Object);
  }
  
  
  Handle<Object> GetPropertyWithInterceptor(Handle<JSObject> receiver,
                                            Handle<JSObject> holder,
                                            Handle<String> name,
                                            PropertyAttributes* attributes) {
    CALL_HEAP_FUNCTION(holder->GetPropertyWithInterceptor(*receiver,
                                                          *name,
                                                          attributes),
                       Object);
  }
  
  
  Handle<Object> GetPrototype(Handle<Object> obj) {
    Handle<Object> result(obj->GetPrototype());
    return result;
  }
  
  
  Handle<Object> SetPrototype(Handle<JSObject> obj, Handle<Object> value) {
    const bool skip_hidden_prototypes = false;
    CALL_HEAP_FUNCTION(obj->SetPrototype(*value, skip_hidden_prototypes), Object);
  }
  
  
  Handle<Object> GetHiddenProperties(Handle<JSObject> obj,
                                     bool create_if_needed) {
    Object* holder = obj->BypassGlobalProxy();
    if (holder->IsUndefined()) return Factory::undefined_value();
    obj = Handle<JSObject>(JSObject::cast(holder));
  
    if (obj->HasFastProperties()) {
      // If the object has fast properties, check whether the first slot
      // in the descriptor array matches the hidden symbol. Since the
      // hidden symbols hash code is zero (and no other string has hash
      // code zero) it will always occupy the first entry if present.
      DescriptorArray* descriptors = obj->map()->instance_descriptors();
      if ((descriptors->number_of_descriptors() > 0) &&
          (descriptors->GetKey(0) == Heap::hidden_symbol()) &&
          descriptors->IsProperty(0)) {
        ASSERT(descriptors->GetType(0) == FIELD);
        return Handle<Object>(obj->FastPropertyAt(descriptors->GetFieldIndex(0)));
      }
    }
  
    // Only attempt to find the hidden properties in the local object and not
    // in the prototype chain.  Note that HasLocalProperty() can cause a GC in
    // the general case in the presence of interceptors.
    if (!obj->HasHiddenPropertiesObject()) {
      // Hidden properties object not found. Allocate a new hidden properties
      // object if requested. Otherwise return the undefined value.
      if (create_if_needed) {
        Handle<Object> hidden_obj = Factory::NewJSObject(Top::object_function());
        CALL_HEAP_FUNCTION(obj->SetHiddenPropertiesObject(*hidden_obj), Object);
      } else {
        return Factory::undefined_value();
      }
    }
    return Handle<Object>(obj->GetHiddenPropertiesObject());
  }
  
  
  Handle<Object> DeleteElement(Handle<JSObject> obj,
                               uint32_t index) {
    CALL_HEAP_FUNCTION(obj->DeleteElement(index, JSObject::NORMAL_DELETION),
                       Object);
  }
  
  
  Handle<Object> DeleteProperty(Handle<JSObject> obj,
                                Handle<String> prop) {
    CALL_HEAP_FUNCTION(obj->DeleteProperty(*prop, JSObject::NORMAL_DELETION),
                       Object);
  }
  
  
  Handle<Object> LookupSingleCharacterStringFromCode(uint32_t index) {
    CALL_HEAP_FUNCTION(Heap::LookupSingleCharacterStringFromCode(index), Object);
  }
  
  
  Handle<String> SubString(Handle<String> str,
                           int start,
                           int end,
                           PretenureFlag pretenure) {
    CALL_HEAP_FUNCTION(str->SubString(start, end, pretenure), String);
  }
  
  
  Handle<Object> SetElement(Handle<JSObject> object,
                            uint32_t index,
                            Handle<Object> value) {
    if (object->HasPixelElements() || object->HasExternalArrayElements()) {
      if (!value->IsSmi() && !value->IsHeapNumber() && !value->IsUndefined()) {
        bool has_exception;
        Handle<Object> number = Execution::ToNumber(value, &has_exception);
        if (has_exception) return Handle<Object>();
        value = number;
      }
    }
    CALL_HEAP_FUNCTION(object->SetElement(index, *value), Object);
  }
  
  
  Handle<JSObject> Copy(Handle<JSObject> obj) {
    CALL_HEAP_FUNCTION(Heap::CopyJSObject(*obj), JSObject);
  }
  
  
  // Wrappers for scripts are kept alive and cached in weak global
  // handles referred from proxy objects held by the scripts as long as
  // they are used. When they are not used anymore, the garbage
  // collector will call the weak callback on the global handle
  // associated with the wrapper and get rid of both the wrapper and the
  // handle.
  static void ClearWrapperCache(Persistent<v8::Value> handle, void*) {
  #ifdef ENABLE_HEAP_PROTECTION
    // Weak reference callbacks are called as if from outside V8.  We
    // need to reeenter to unprotect the heap.
    VMState state(OTHER);
  #endif
    Handle<Object> cache = Utils::OpenHandle(*handle);
    JSValue* wrapper = JSValue::cast(*cache);
    Proxy* proxy = Script::cast(wrapper->value())->wrapper();
    ASSERT(proxy->proxy() == reinterpret_cast<Address>(cache.location()));
    proxy->set_proxy(0);
    GlobalHandles::Destroy(cache.location());
    Counters::script_wrappers.Decrement();
  }
  
  
  Handle<JSValue> GetScriptWrapper(Handle<Script> script) {
    if (script->wrapper()->proxy() != NULL) {
      // Return the script wrapper directly from the cache.
      return Handle<JSValue>(
          reinterpret_cast<JSValue**>(script->wrapper()->proxy()));
    }
  
    // Construct a new script wrapper.
    Counters::script_wrappers.Increment();
    Handle<JSFunction> constructor = Top::script_function();
    Handle<JSValue> result =
        Handle<JSValue>::cast(Factory::NewJSObject(constructor));
    result->set_value(*script);
  
    // Create a new weak global handle and use it to cache the wrapper
    // for future use. The cache will automatically be cleared by the
    // garbage collector when it is not used anymore.
    Handle<Object> handle = GlobalHandles::Create(*result);
    GlobalHandles::MakeWeak(handle.location(), NULL, &ClearWrapperCache);
    script->wrapper()->set_proxy(reinterpret_cast<Address>(handle.location()));
    return result;
  }
  
  
  // Init line_ends array with code positions of line ends inside script
  // source.
  void InitScriptLineEnds(Handle<Script> script) {
    if (!script->line_ends()->IsUndefined()) return;
  
    if (!script->source()->IsString()) {
      ASSERT(script->source()->IsUndefined());
      script->set_line_ends(*(Factory::NewFixedArray(0)));
      ASSERT(script->line_ends()->IsFixedArray());
      return;
    }
  
    Handle<String> src(String::cast(script->source()));
    const int src_len = src->length();
    Handle<String> new_line = Factory::NewStringFromAscii(CStrVector("\n"));
  
    // Pass 1: Identify line count.
    int line_count = 0;
    int position = 0;
    while (position != -1 && position < src_len) {
      position = Runtime::StringMatch(src, new_line, position);
      if (position != -1) {
        position++;
      }
      // Even if the last line misses a line end, it is counted.
      line_count++;
    }
  
    // Pass 2: Fill in line ends positions
    Handle<FixedArray> array = Factory::NewFixedArray(line_count);
    int array_index = 0;
    position = 0;
    while (position != -1 && position < src_len) {
      position = Runtime::StringMatch(src, new_line, position);
      // If the script does not end with a line ending add the final end
      // position as just past the last line ending.
      array->set(array_index++,
                 Smi::FromInt(position != -1 ? position++ : src_len));
    }
    ASSERT(array_index == line_count);
  
    script->set_line_ends(*array);
    ASSERT(script->line_ends()->IsFixedArray());
  }
  
  
  // Convert code position into line number.
  int GetScriptLineNumber(Handle<Script> script, int code_pos) {
    InitScriptLineEnds(script);
    AssertNoAllocation no_allocation;
    FixedArray* line_ends_array = FixedArray::cast(script->line_ends());
    const int line_ends_len = line_ends_array->length();
  
    if (!line_ends_len)
      return -1;
  
    if ((Smi::cast(line_ends_array->get(0)))->value() >= code_pos)
      return script->line_offset()->value();
  
    int left = 0;
    int right = line_ends_len;
    while (int half = (right - left) / 2) {
      if ((Smi::cast(line_ends_array->get(left + half)))->value() > code_pos) {
        right -= half;
      } else {
        left += half;
      }
    }
    return right + script->line_offset()->value();
  }
  
  
  int GetScriptLineNumberSafe(Handle<Script> script, int code_pos) {
    AssertNoAllocation no_allocation;
    if (!script->line_ends()->IsUndefined()) {
      return GetScriptLineNumber(script, code_pos);
    }
    // Slow mode: we do not have line_ends. We have to iterate through source.
    if (!script->source()->IsString()) {
      return -1;
    }
    String* source = String::cast(script->source());
    int line = 0;
    int len = source->length();
    for (int pos = 0; pos < len; pos++) {
      if (pos == code_pos) {
        break;
      }
      if (source->Get(pos) == '\n') {
        line++;
      }
    }
    return line;
  }
  
  
  void CustomArguments::IterateInstance(ObjectVisitor* v) {
    v->VisitPointers(values_, values_ + ARRAY_SIZE(values_));
  }
  
  
  // Compute the property keys from the interceptor.
  v8::Handle<v8::Array> GetKeysForNamedInterceptor(Handle<JSObject> receiver,
                                                   Handle<JSObject> object) {
    Handle<InterceptorInfo> interceptor(object->GetNamedInterceptor());
    CustomArguments args(interceptor->data(), *receiver, *object);
    v8::AccessorInfo info(args.end());
    v8::Handle<v8::Array> result;
    if (!interceptor->enumerator()->IsUndefined()) {
      v8::NamedPropertyEnumerator enum_fun =
          v8::ToCData<v8::NamedPropertyEnumerator>(interceptor->enumerator());
      LOG(ApiObjectAccess("interceptor-named-enum", *object));
      {
        // Leaving JavaScript.
        VMState state(EXTERNAL);
        result = enum_fun(info);
      }
    }
    return result;
  }
  
  
  // Compute the element keys from the interceptor.
  v8::Handle<v8::Array> GetKeysForIndexedInterceptor(Handle<JSObject> receiver,
                                                     Handle<JSObject> object) {
    Handle<InterceptorInfo> interceptor(object->GetIndexedInterceptor());
    CustomArguments args(interceptor->data(), *receiver, *object);
    v8::AccessorInfo info(args.end());
    v8::Handle<v8::Array> result;
    if (!interceptor->enumerator()->IsUndefined()) {
      v8::IndexedPropertyEnumerator enum_fun =
          v8::ToCData<v8::IndexedPropertyEnumerator>(interceptor->enumerator());
      LOG(ApiObjectAccess("interceptor-indexed-enum", *object));
      {
        // Leaving JavaScript.
        VMState state(EXTERNAL);
        result = enum_fun(info);
      }
    }
    return result;
  }
  
  
  Handle<FixedArray> GetKeysInFixedArrayFor(Handle<JSObject> object,
                                            KeyCollectionType type) {
    Handle<FixedArray> content = Factory::empty_fixed_array();
    Handle<JSObject> arguments_boilerplate =
        Handle<JSObject>(
            Top::context()->global_context()->arguments_boilerplate());
    Handle<JSFunction> arguments_function =
        Handle<JSFunction>(
            JSFunction::cast(arguments_boilerplate->map()->constructor()));
  
    // Only collect keys if access is permitted.
    for (Handle<Object> p = object;
         *p != Heap::null_value();
         p = Handle<Object>(p->GetPrototype())) {
      Handle<JSObject> current(JSObject::cast(*p));
  
      // Check access rights if required.
      if (current->IsAccessCheckNeeded() &&
        !Top::MayNamedAccess(*current, Heap::undefined_value(),
                             v8::ACCESS_KEYS)) {
        Top::ReportFailedAccessCheck(*current, v8::ACCESS_KEYS);
        break;
      }
  
      // Compute the element keys.
      Handle<FixedArray> element_keys =
          Factory::NewFixedArray(current->NumberOfEnumElements());
      current->GetEnumElementKeys(*element_keys);
      content = UnionOfKeys(content, element_keys);
  
      // Add the element keys from the interceptor.
      if (current->HasIndexedInterceptor()) {
        v8::Handle<v8::Array> result =
            GetKeysForIndexedInterceptor(object, current);
        if (!result.IsEmpty())
          content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
      }
  
      // We can cache the computed property keys if access checks are
      // not needed and no interceptors are involved.
      //
      // We do not use the cache if the object has elements and
      // therefore it does not make sense to cache the property names
      // for arguments objects.  Arguments objects will always have
      // elements.
      bool cache_enum_keys =
          ((current->map()->constructor() != *arguments_function) &&
           !current->IsAccessCheckNeeded() &&
           !current->HasNamedInterceptor() &&
           !current->HasIndexedInterceptor());
      // Compute the property keys and cache them if possible.
      content =
          UnionOfKeys(content, GetEnumPropertyKeys(current, cache_enum_keys));
  
      // Add the property keys from the interceptor.
      if (current->HasNamedInterceptor()) {
        v8::Handle<v8::Array> result =
            GetKeysForNamedInterceptor(object, current);
        if (!result.IsEmpty())
          content = AddKeysFromJSArray(content, v8::Utils::OpenHandle(*result));
      }
  
      // If we only want local properties we bail out after the first
      // iteration.
      if (type == LOCAL_ONLY)
        break;
    }
    return content;
  }
  
  
  Handle<JSArray> GetKeysFor(Handle<JSObject> object) {
    Counters::for_in.Increment();
    Handle<FixedArray> elements = GetKeysInFixedArrayFor(object,
                                                         INCLUDE_PROTOS);
    return Factory::NewJSArrayWithElements(elements);
  }
  
  
  Handle<FixedArray> GetEnumPropertyKeys(Handle<JSObject> object,
                                         bool cache_result) {
    int index = 0;
    if (object->HasFastProperties()) {
      if (object->map()->instance_descriptors()->HasEnumCache()) {
        Counters::enum_cache_hits.Increment();
        DescriptorArray* desc = object->map()->instance_descriptors();
        return Handle<FixedArray>(FixedArray::cast(desc->GetEnumCache()));
      }
      Counters::enum_cache_misses.Increment();
      int num_enum = object->NumberOfEnumProperties();
      Handle<FixedArray> storage = Factory::NewFixedArray(num_enum);
      Handle<FixedArray> sort_array = Factory::NewFixedArray(num_enum);
      Handle<DescriptorArray> descs =
          Handle<DescriptorArray>(object->map()->instance_descriptors());
      for (int i = 0; i < descs->number_of_descriptors(); i++) {
        if (descs->IsProperty(i) && !descs->IsDontEnum(i)) {
          (*storage)->set(index, descs->GetKey(i));
          PropertyDetails details(descs->GetDetails(i));
          (*sort_array)->set(index, Smi::FromInt(details.index()));
          index++;
        }
      }
      (*storage)->SortPairs(*sort_array, sort_array->length());
      if (cache_result) {
        Handle<FixedArray> bridge_storage =
            Factory::NewFixedArray(DescriptorArray::kEnumCacheBridgeLength);
        DescriptorArray* desc = object->map()->instance_descriptors();
        desc->SetEnumCache(*bridge_storage, *storage);
      }
      ASSERT(storage->length() == index);
      return storage;
    } else {
      int num_enum = object->NumberOfEnumProperties();
      Handle<FixedArray> storage = Factory::NewFixedArray(num_enum);
      Handle<FixedArray> sort_array = Factory::NewFixedArray(num_enum);
      object->property_dictionary()->CopyEnumKeysTo(*storage, *sort_array);
      return storage;
    }
  }
  
  
  bool EnsureCompiled(Handle<SharedFunctionInfo> shared,
                      ClearExceptionFlag flag) {
    return shared->is_compiled() || CompileLazyShared(shared, flag);
  }
  
  
  static bool CompileLazyHelper(CompilationInfo* info,
                                ClearExceptionFlag flag) {
    // Compile the source information to a code object.
    ASSERT(!info->shared_info()->is_compiled());
    bool result = Compiler::CompileLazy(info);
    ASSERT(result != Top::has_pending_exception());
    if (!result && flag == CLEAR_EXCEPTION) Top::clear_pending_exception();
    return result;
  }
  
  
  bool CompileLazyShared(Handle<SharedFunctionInfo> shared,
                         ClearExceptionFlag flag) {
    CompilationInfo info(shared);
    return CompileLazyHelper(&info, flag);
  }
  
  
  bool CompileLazy(Handle<JSFunction> function,
                   Handle<Object> receiver,
                   ClearExceptionFlag flag) {
    CompilationInfo info(function, 0, receiver);
    bool result = CompileLazyHelper(&info, flag);
    LOG(FunctionCreateEvent(*function));
    return result;
  }
  
  
  bool CompileLazyInLoop(Handle<JSFunction> function,
                         Handle<Object> receiver,
                         ClearExceptionFlag flag) {
    CompilationInfo info(function, 1, receiver);
    bool result = CompileLazyHelper(&info, flag);
    LOG(FunctionCreateEvent(*function));
    return result;
  }
  
  
  OptimizedObjectForAddingMultipleProperties::
  OptimizedObjectForAddingMultipleProperties(Handle<JSObject> object,
                                             int expected_additional_properties,
                                             bool condition) {
    object_ = object;
    if (condition && object_->HasFastProperties()) {
      // Normalize the properties of object to avoid n^2 behavior
      // when extending the object multiple properties. Indicate the number of
      // properties to be added.
      unused_property_fields_ = object->map()->unused_property_fields();
      NormalizeProperties(object_,
                          KEEP_INOBJECT_PROPERTIES,
                          expected_additional_properties);
      has_been_transformed_ = true;
  
    } else {
      has_been_transformed_ = false;
    }
  }
  
  
  Handle<Code> ComputeLazyCompile(int argc) {
    CALL_HEAP_FUNCTION(StubCache::ComputeLazyCompile(argc), Code);
  }
  
  
  OptimizedObjectForAddingMultipleProperties::
  ~OptimizedObjectForAddingMultipleProperties() {
    // Reoptimize the object to allow fast property access.
    if (has_been_transformed_) {
      TransformToFastProperties(object_, unused_property_fields_);
    }
  }
  
  } }  // namespace v8::internal
  