src/factory.cc

// Copyright 2010 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 "api.h"
#include "debug.h"
#include "execution.h"
#include "factory.h"
#include "macro-assembler.h"
#include "objects.h"
#include "objects-visiting.h"

namespace v8 {
namespace internal {


Handle<FixedArray> Factory::NewFixedArray(int size, PretenureFlag pretenure) {
  ASSERT(0 <= size);
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFixedArray(size, pretenure),
      FixedArray);
}


Handle<FixedArray> Factory::NewFixedArrayWithHoles(int size,
                                                   PretenureFlag pretenure) {
  ASSERT(0 <= size);
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFixedArrayWithHoles(size, pretenure),
      FixedArray);
}


Handle<StringDictionary> Factory::NewStringDictionary(int at_least_space_for) {
  ASSERT(0 <= at_least_space_for);
  CALL_HEAP_FUNCTION(isolate(),
                     StringDictionary::Allocate(at_least_space_for),
                     StringDictionary);
}


Handle<NumberDictionary> Factory::NewNumberDictionary(int at_least_space_for) {
  ASSERT(0 <= at_least_space_for);
  CALL_HEAP_FUNCTION(isolate(),
                     NumberDictionary::Allocate(at_least_space_for),
                     NumberDictionary);
}


Handle<DescriptorArray> Factory::NewDescriptorArray(int number_of_descriptors) {
  ASSERT(0 <= number_of_descriptors);
  CALL_HEAP_FUNCTION(isolate(),
                     DescriptorArray::Allocate(number_of_descriptors),
                     DescriptorArray);
}


Handle<DeoptimizationInputData> Factory::NewDeoptimizationInputData(
    int deopt_entry_count,
    PretenureFlag pretenure) {
  ASSERT(deopt_entry_count > 0);
  CALL_HEAP_FUNCTION(isolate(),
                     DeoptimizationInputData::Allocate(deopt_entry_count,
                                                       pretenure),
                     DeoptimizationInputData);
}


Handle<DeoptimizationOutputData> Factory::NewDeoptimizationOutputData(
    int deopt_entry_count,
    PretenureFlag pretenure) {
  ASSERT(deopt_entry_count > 0);
  CALL_HEAP_FUNCTION(isolate(),
                     DeoptimizationOutputData::Allocate(deopt_entry_count,
                                                        pretenure),
                     DeoptimizationOutputData);
}


// Symbols are created in the old generation (data space).
Handle<String> Factory::LookupSymbol(Vector<const char> string) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->LookupSymbol(string),
                     String);
}

Handle<String> Factory::LookupAsciiSymbol(Vector<const char> string) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->LookupAsciiSymbol(string),
                     String);
}

Handle<String> Factory::LookupTwoByteSymbol(Vector<const uc16> string) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->LookupTwoByteSymbol(string),
                     String);
}


Handle<String> Factory::NewStringFromAscii(Vector<const char> string,
                                           PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateStringFromAscii(string, pretenure),
      String);
}

Handle<String> Factory::NewStringFromUtf8(Vector<const char> string,
                                          PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateStringFromUtf8(string, pretenure),
      String);
}


Handle<String> Factory::NewStringFromTwoByte(Vector<const uc16> string,
                                             PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateStringFromTwoByte(string, pretenure),
      String);
}


Handle<String> Factory::NewRawAsciiString(int length,
                                          PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateRawAsciiString(length, pretenure),
      String);
}


Handle<String> Factory::NewRawTwoByteString(int length,
                                            PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateRawTwoByteString(length, pretenure),
      String);
}


Handle<String> Factory::NewConsString(Handle<String> first,
                                      Handle<String> second) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateConsString(*first, *second),
                     String);
}


Handle<String> Factory::NewSubString(Handle<String> str,
                                     int begin,
                                     int end) {
  CALL_HEAP_FUNCTION(isolate(),
                     str->SubString(begin, end),
                     String);
}


Handle<String> Factory::NewExternalStringFromAscii(
    ExternalAsciiString::Resource* resource) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateExternalStringFromAscii(resource),
      String);
}


Handle<String> Factory::NewExternalStringFromTwoByte(
    ExternalTwoByteString::Resource* resource) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateExternalStringFromTwoByte(resource),
      String);
}


Handle<Context> Factory::NewGlobalContext() {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateGlobalContext(),
      Context);
}


Handle<Context> Factory::NewFunctionContext(int length,
                                            Handle<JSFunction> closure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFunctionContext(length, *closure),
      Context);
}


Handle<Context> Factory::NewWithContext(Handle<Context> previous,
                                        Handle<JSObject> extension,
                                        bool is_catch_context) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateWithContext(*previous,
                                             *extension,
                                             is_catch_context),
      Context);
}


Handle<Struct> Factory::NewStruct(InstanceType type) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateStruct(type),
      Struct);
}


Handle<AccessorInfo> Factory::NewAccessorInfo() {
  Handle<AccessorInfo> info =
      Handle<AccessorInfo>::cast(NewStruct(ACCESSOR_INFO_TYPE));
  info->set_flag(0);  // Must clear the flag, it was initialized as undefined.
  return info;
}


Handle<Script> Factory::NewScript(Handle<String> source) {
  // Generate id for this script.
  int id;
  Heap* heap = isolate()->heap();
  if (heap->last_script_id()->IsUndefined()) {
    // Script ids start from one.
    id = 1;
  } else {
    // Increment id, wrap when positive smi is exhausted.
    id = Smi::cast(heap->last_script_id())->value();
    id++;
    if (!Smi::IsValid(id)) {
      id = 0;
    }
  }
  heap->SetLastScriptId(Smi::FromInt(id));

  // Create and initialize script object.
  Handle<Proxy> wrapper = NewProxy(0, TENURED);
  Handle<Script> script = Handle<Script>::cast(NewStruct(SCRIPT_TYPE));
  script->set_source(*source);
  script->set_name(heap->undefined_value());
  script->set_id(heap->last_script_id());
  script->set_line_offset(Smi::FromInt(0));
  script->set_column_offset(Smi::FromInt(0));
  script->set_data(heap->undefined_value());
  script->set_context_data(heap->undefined_value());
  script->set_type(Smi::FromInt(Script::TYPE_NORMAL));
  script->set_compilation_type(Smi::FromInt(Script::COMPILATION_TYPE_HOST));
  script->set_wrapper(*wrapper);
  script->set_line_ends(heap->undefined_value());
  script->set_eval_from_shared(heap->undefined_value());
  script->set_eval_from_instructions_offset(Smi::FromInt(0));

  return script;
}


Handle<Proxy> Factory::NewProxy(Address addr, PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateProxy(addr, pretenure),
                     Proxy);
}


Handle<Proxy> Factory::NewProxy(const AccessorDescriptor* desc) {
  return NewProxy((Address) desc, TENURED);
}


Handle<ByteArray> Factory::NewByteArray(int length, PretenureFlag pretenure) {
  ASSERT(0 <= length);
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateByteArray(length, pretenure),
      ByteArray);
}


Handle<ExternalArray> Factory::NewExternalArray(int length,
                                                ExternalArrayType array_type,
                                                void* external_pointer,
                                                PretenureFlag pretenure) {
  ASSERT(0 <= length);
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateExternalArray(length,
                                               array_type,
                                               external_pointer,
                                               pretenure),
      ExternalArray);
}


Handle<JSGlobalPropertyCell> Factory::NewJSGlobalPropertyCell(
    Handle<Object> value) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateJSGlobalPropertyCell(*value),
      JSGlobalPropertyCell);
}


Handle<Map> Factory::NewMap(InstanceType type, int instance_size) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateMap(type, instance_size),
      Map);
}


Handle<JSObject> Factory::NewFunctionPrototype(Handle<JSFunction> function) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFunctionPrototype(*function),
      JSObject);
}


Handle<Map> Factory::CopyMapDropDescriptors(Handle<Map> src) {
  CALL_HEAP_FUNCTION(isolate(), src->CopyDropDescriptors(), Map);
}


Handle<Map> Factory::CopyMap(Handle<Map> src,
                             int extra_inobject_properties) {
  Handle<Map> copy = CopyMapDropDescriptors(src);
  // Check that we do not overflow the instance size when adding the
  // extra inobject properties.
  int instance_size_delta = extra_inobject_properties * kPointerSize;
  int max_instance_size_delta =
      JSObject::kMaxInstanceSize - copy->instance_size();
  if (instance_size_delta > max_instance_size_delta) {
    // If the instance size overflows, we allocate as many properties
    // as we can as inobject properties.
    instance_size_delta = max_instance_size_delta;
    extra_inobject_properties = max_instance_size_delta >> kPointerSizeLog2;
  }
  // Adjust the map with the extra inobject properties.
  int inobject_properties =
      copy->inobject_properties() + extra_inobject_properties;
  copy->set_inobject_properties(inobject_properties);
  copy->set_unused_property_fields(inobject_properties);
  copy->set_instance_size(copy->instance_size() + instance_size_delta);
  copy->set_visitor_id(StaticVisitorBase::GetVisitorId(*copy));
  return copy;
}


Handle<Map> Factory::CopyMapDropTransitions(Handle<Map> src) {
  CALL_HEAP_FUNCTION(isolate(), src->CopyDropTransitions(), Map);
}


Handle<Map> Factory::GetFastElementsMap(Handle<Map> src) {
  CALL_HEAP_FUNCTION(isolate(), src->GetFastElementsMap(), Map);
}


Handle<Map> Factory::GetSlowElementsMap(Handle<Map> src) {
  CALL_HEAP_FUNCTION(isolate(), src->GetSlowElementsMap(), Map);
}


Handle<Map> Factory::NewExternalArrayElementsMap(Handle<Map> src) {
  CALL_HEAP_FUNCTION(isolate(), src->NewExternalArrayElementsMap(), Map);
}


Handle<FixedArray> Factory::CopyFixedArray(Handle<FixedArray> array) {
  CALL_HEAP_FUNCTION(isolate(), array->Copy(), FixedArray);
}


Handle<JSFunction> Factory::BaseNewFunctionFromSharedFunctionInfo(
    Handle<SharedFunctionInfo> function_info,
    Handle<Map> function_map,
    PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFunction(*function_map,
                                          *function_info,
                                          isolate()->heap()->the_hole_value(),
                                          pretenure),
                     JSFunction);
}


Handle<JSFunction> Factory::NewFunctionFromSharedFunctionInfo(
    Handle<SharedFunctionInfo> function_info,
    Handle<Context> context,
    PretenureFlag pretenure) {
  Handle<JSFunction> result = BaseNewFunctionFromSharedFunctionInfo(
      function_info,
      function_info->strict_mode()
          ? isolate()->strict_mode_function_map()
          : isolate()->function_map(),
      pretenure);

  result->set_context(*context);
  int number_of_literals = function_info->num_literals();
  Handle<FixedArray> literals = NewFixedArray(number_of_literals, pretenure);
  if (number_of_literals > 0) {
    // Store the object, regexp and array functions in the literals
    // array prefix.  These functions will be used when creating
    // object, regexp and array literals in this function.
    literals->set(JSFunction::kLiteralGlobalContextIndex,
                  context->global_context());
  }
  result->set_literals(*literals);
  result->set_next_function_link(isolate()->heap()->undefined_value());

  if (V8::UseCrankshaft() &&
      FLAG_always_opt &&
      result->is_compiled() &&
      !function_info->is_toplevel() &&
      function_info->allows_lazy_compilation()) {
    result->MarkForLazyRecompilation();
  }
  return result;
}


Handle<Object> Factory::NewNumber(double value,
                                  PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->NumberFromDouble(value, pretenure), Object);
}


Handle<Object> Factory::NewNumberFromInt(int value) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->NumberFromInt32(value), Object);
}


Handle<Object> Factory::NewNumberFromUint(uint32_t value) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->NumberFromUint32(value), Object);
}


Handle<JSObject> Factory::NewNeanderObject() {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateJSObjectFromMap(
          isolate()->heap()->neander_map()),
      JSObject);
}


Handle<Object> Factory::NewTypeError(const char* type,
                                     Vector< Handle<Object> > args) {
  return NewError("MakeTypeError", type, args);
}


Handle<Object> Factory::NewTypeError(Handle<String> message) {
  return NewError("$TypeError", message);
}


Handle<Object> Factory::NewRangeError(const char* type,
                                      Vector< Handle<Object> > args) {
  return NewError("MakeRangeError", type, args);
}


Handle<Object> Factory::NewRangeError(Handle<String> message) {
  return NewError("$RangeError", message);
}


Handle<Object> Factory::NewSyntaxError(const char* type, Handle<JSArray> args) {
  return NewError("MakeSyntaxError", type, args);
}


Handle<Object> Factory::NewSyntaxError(Handle<String> message) {
  return NewError("$SyntaxError", message);
}


Handle<Object> Factory::NewReferenceError(const char* type,
                                          Vector< Handle<Object> > args) {
  return NewError("MakeReferenceError", type, args);
}


Handle<Object> Factory::NewReferenceError(Handle<String> message) {
  return NewError("$ReferenceError", message);
}


Handle<Object> Factory::NewError(const char* maker, const char* type,
    Vector< Handle<Object> > args) {
  v8::HandleScope scope;  // Instantiate a closeable HandleScope for EscapeFrom.
  Handle<FixedArray> array = NewFixedArray(args.length());
  for (int i = 0; i < args.length(); i++) {
    array->set(i, *args[i]);
  }
  Handle<JSArray> object = NewJSArrayWithElements(array);
  Handle<Object> result = NewError(maker, type, object);
  return result.EscapeFrom(&scope);
}


Handle<Object> Factory::NewEvalError(const char* type,
                                     Vector< Handle<Object> > args) {
  return NewError("MakeEvalError", type, args);
}


Handle<Object> Factory::NewError(const char* type,
                                 Vector< Handle<Object> > args) {
  return NewError("MakeError", type, args);
}


Handle<Object> Factory::NewError(const char* maker,
                                 const char* type,
                                 Handle<JSArray> args) {
  Handle<String> make_str = LookupAsciiSymbol(maker);
  Handle<Object> fun_obj(
      isolate()->js_builtins_object()->GetPropertyNoExceptionThrown(*make_str));
  // If the builtins haven't been properly configured yet this error
  // constructor may not have been defined.  Bail out.
  if (!fun_obj->IsJSFunction())
    return undefined_value();
  Handle<JSFunction> fun = Handle<JSFunction>::cast(fun_obj);
  Handle<Object> type_obj = LookupAsciiSymbol(type);
  Object** argv[2] = { type_obj.location(),
                       Handle<Object>::cast(args).location() };

  // Invoke the JavaScript factory method. If an exception is thrown while
  // running the factory method, use the exception as the result.
  bool caught_exception;
  Handle<Object> result = Execution::TryCall(fun,
      isolate()->js_builtins_object(), 2, argv, &caught_exception);
  return result;
}


Handle<Object> Factory::NewError(Handle<String> message) {
  return NewError("$Error", message);
}


Handle<Object> Factory::NewError(const char* constructor,
                                 Handle<String> message) {
  Handle<String> constr = LookupAsciiSymbol(constructor);
  Handle<JSFunction> fun = Handle<JSFunction>(
      JSFunction::cast(isolate()->js_builtins_object()->
                       GetPropertyNoExceptionThrown(*constr)));
  Object** argv[1] = { Handle<Object>::cast(message).location() };

  // Invoke the JavaScript factory method. If an exception is thrown while
  // running the factory method, use the exception as the result.
  bool caught_exception;
  Handle<Object> result = Execution::TryCall(fun,
      isolate()->js_builtins_object(), 1, argv, &caught_exception);
  return result;
}


Handle<JSFunction> Factory::NewFunction(Handle<String> name,
                                        InstanceType type,
                                        int instance_size,
                                        Handle<Code> code,
                                        bool force_initial_map) {
  // Allocate the function
  Handle<JSFunction> function = NewFunction(name, the_hole_value());

  // Setup the code pointer in both the shared function info and in
  // the function itself.
  function->shared()->set_code(*code);
  function->set_code(*code);

  if (force_initial_map ||
      type != JS_OBJECT_TYPE ||
      instance_size != JSObject::kHeaderSize) {
    Handle<Map> initial_map = NewMap(type, instance_size);
    Handle<JSObject> prototype = NewFunctionPrototype(function);
    initial_map->set_prototype(*prototype);
    function->set_initial_map(*initial_map);
    initial_map->set_constructor(*function);
  } else {
    ASSERT(!function->has_initial_map());
    ASSERT(!function->has_prototype());
  }

  return function;
}


Handle<JSFunction> Factory::NewFunctionWithPrototype(Handle<String> name,
                                                     InstanceType type,
                                                     int instance_size,
                                                     Handle<JSObject> prototype,
                                                     Handle<Code> code,
                                                     bool force_initial_map) {
  // Allocate the function.
  Handle<JSFunction> function = NewFunction(name, prototype);

  // Setup the code pointer in both the shared function info and in
  // the function itself.
  function->shared()->set_code(*code);
  function->set_code(*code);

  if (force_initial_map ||
      type != JS_OBJECT_TYPE ||
      instance_size != JSObject::kHeaderSize) {
    Handle<Map> initial_map = NewMap(type, instance_size);
    function->set_initial_map(*initial_map);
    initial_map->set_constructor(*function);
  }

  // Set function.prototype and give the prototype a constructor
  // property that refers to the function.
  SetPrototypeProperty(function, prototype);
  // Currently safe because it is only invoked from Genesis.
  SetLocalPropertyNoThrow(prototype, constructor_symbol(), function, DONT_ENUM);
  return function;
}


Handle<JSFunction> Factory::NewFunctionWithoutPrototype(Handle<String> name,
                                                        Handle<Code> code) {
  Handle<JSFunction> function = NewFunctionWithoutPrototype(name,
                                                            kNonStrictMode);
  function->shared()->set_code(*code);
  function->set_code(*code);
  ASSERT(!function->has_initial_map());
  ASSERT(!function->has_prototype());
  return function;
}


Handle<Code> Factory::NewCode(const CodeDesc& desc,
                              Code::Flags flags,
                              Handle<Object> self_ref,
                              bool immovable) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->CreateCode(
                         desc, flags, self_ref, immovable),
                     Code);
}


Handle<Code> Factory::CopyCode(Handle<Code> code) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->CopyCode(*code),
                     Code);
}


Handle<Code> Factory::CopyCode(Handle<Code> code, Vector<byte> reloc_info) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->CopyCode(*code, reloc_info),
                     Code);
}


MUST_USE_RESULT static inline MaybeObject* DoCopyInsert(
    DescriptorArray* array,
    String* key,
    Object* value,
    PropertyAttributes attributes) {
  CallbacksDescriptor desc(key, value, attributes);
  MaybeObject* obj = array->CopyInsert(&desc, REMOVE_TRANSITIONS);
  return obj;
}


// Allocate the new array.
Handle<DescriptorArray> Factory::CopyAppendProxyDescriptor(
    Handle<DescriptorArray> array,
    Handle<String> key,
    Handle<Object> value,
    PropertyAttributes attributes) {
  CALL_HEAP_FUNCTION(isolate(),
                     DoCopyInsert(*array, *key, *value, attributes),
                     DescriptorArray);
}


Handle<String> Factory::SymbolFromString(Handle<String> value) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->LookupSymbol(*value), String);
}


Handle<DescriptorArray> Factory::CopyAppendCallbackDescriptors(
    Handle<DescriptorArray> array,
    Handle<Object> descriptors) {
  v8::NeanderArray callbacks(descriptors);
  int nof_callbacks = callbacks.length();
  Handle<DescriptorArray> result =
      NewDescriptorArray(array->number_of_descriptors() + nof_callbacks);

  // Number of descriptors added to the result so far.
  int descriptor_count = 0;

  // Copy the descriptors from the array.
  for (int i = 0; i < array->number_of_descriptors(); i++) {
    if (array->GetType(i) != NULL_DESCRIPTOR) {
      result->CopyFrom(descriptor_count++, *array, i);
    }
  }

  // Number of duplicates detected.
  int duplicates = 0;

  // Fill in new callback descriptors.  Process the callbacks from
  // back to front so that the last callback with a given name takes
  // precedence over previously added callbacks with that name.
  for (int i = nof_callbacks - 1; i >= 0; i--) {
    Handle<AccessorInfo> entry =
        Handle<AccessorInfo>(AccessorInfo::cast(callbacks.get(i)));
    // Ensure the key is a symbol before writing into the instance descriptor.
    Handle<String> key =
        SymbolFromString(Handle<String>(String::cast(entry->name())));
    // Check if a descriptor with this name already exists before writing.
    if (result->LinearSearch(*key, descriptor_count) ==
        DescriptorArray::kNotFound) {
      CallbacksDescriptor desc(*key, *entry, entry->property_attributes());
      result->Set(descriptor_count, &desc);
      descriptor_count++;
    } else {
      duplicates++;
    }
  }

  // If duplicates were detected, allocate a result of the right size
  // and transfer the elements.
  if (duplicates > 0) {
    int number_of_descriptors = result->number_of_descriptors() - duplicates;
    Handle<DescriptorArray> new_result =
        NewDescriptorArray(number_of_descriptors);
    for (int i = 0; i < number_of_descriptors; i++) {
      new_result->CopyFrom(i, *result, i);
    }
    result = new_result;
  }

  // Sort the result before returning.
  result->Sort();
  return result;
}


Handle<JSObject> Factory::NewJSObject(Handle<JSFunction> constructor,
                                      PretenureFlag pretenure) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateJSObject(*constructor, pretenure), JSObject);
}


Handle<GlobalObject> Factory::NewGlobalObject(
    Handle<JSFunction> constructor) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateGlobalObject(*constructor),
                     GlobalObject);
}



Handle<JSObject> Factory::NewJSObjectFromMap(Handle<Map> map) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateJSObjectFromMap(*map, NOT_TENURED),
      JSObject);
}


Handle<JSArray> Factory::NewJSArray(int capacity,
                                    PretenureFlag pretenure) {
  Handle<JSObject> obj = NewJSObject(isolate()->array_function(), pretenure);
  CALL_HEAP_FUNCTION(isolate(),
                     Handle<JSArray>::cast(obj)->Initialize(capacity),
                     JSArray);
}


Handle<JSArray> Factory::NewJSArrayWithElements(Handle<FixedArray> elements,
                                                PretenureFlag pretenure) {
  Handle<JSArray> result =
      Handle<JSArray>::cast(NewJSObject(isolate()->array_function(),
                                        pretenure));
  result->SetContent(*elements);
  return result;
}


Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(
    Handle<String> name,
    int number_of_literals,
    Handle<Code> code,
    Handle<SerializedScopeInfo> scope_info) {
  Handle<SharedFunctionInfo> shared = NewSharedFunctionInfo(name);
  shared->set_code(*code);
  shared->set_scope_info(*scope_info);
  int literals_array_size = number_of_literals;
  // If the function contains object, regexp or array literals,
  // allocate extra space for a literals array prefix containing the
  // context.
  if (number_of_literals > 0) {
    literals_array_size += JSFunction::kLiteralsPrefixSize;
  }
  shared->set_num_literals(literals_array_size);
  return shared;
}


Handle<JSMessageObject> Factory::NewJSMessageObject(
    Handle<String> type,
    Handle<JSArray> arguments,
    int start_position,
    int end_position,
    Handle<Object> script,
    Handle<Object> stack_trace,
    Handle<Object> stack_frames) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateJSMessageObject(*type,
                         *arguments,
                         start_position,
                         end_position,
                         *script,
                         *stack_trace,
                         *stack_frames),
                     JSMessageObject);
}

Handle<SharedFunctionInfo> Factory::NewSharedFunctionInfo(Handle<String> name) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateSharedFunctionInfo(*name),
                     SharedFunctionInfo);
}


Handle<String> Factory::NumberToString(Handle<Object> number) {
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->NumberToString(*number), String);
}


Handle<NumberDictionary> Factory::DictionaryAtNumberPut(
    Handle<NumberDictionary> dictionary,
    uint32_t key,
    Handle<Object> value) {
  CALL_HEAP_FUNCTION(isolate(),
                     dictionary->AtNumberPut(key, *value),
                     NumberDictionary);
}


Handle<JSFunction> Factory::NewFunctionHelper(Handle<String> name,
                                              Handle<Object> prototype) {
  Handle<SharedFunctionInfo> function_share = NewSharedFunctionInfo(name);
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateFunction(*isolate()->function_map(),
                                          *function_share,
                                          *prototype),
      JSFunction);
}


Handle<JSFunction> Factory::NewFunction(Handle<String> name,
                                        Handle<Object> prototype) {
  Handle<JSFunction> fun = NewFunctionHelper(name, prototype);
  fun->set_context(isolate()->context()->global_context());
  return fun;
}


Handle<JSFunction> Factory::NewFunctionWithoutPrototypeHelper(
    Handle<String> name,
    StrictModeFlag strict_mode) {
  Handle<SharedFunctionInfo> function_share = NewSharedFunctionInfo(name);
  Handle<Map> map = strict_mode == kStrictMode
      ? isolate()->strict_mode_function_without_prototype_map()
      : isolate()->function_without_prototype_map();
  CALL_HEAP_FUNCTION(isolate(),
                     isolate()->heap()->AllocateFunction(
                         *map,
                         *function_share,
                         *the_hole_value()),
                     JSFunction);
}


Handle<JSFunction> Factory::NewFunctionWithoutPrototype(
    Handle<String> name,
    StrictModeFlag strict_mode) {
  Handle<JSFunction> fun = NewFunctionWithoutPrototypeHelper(name, strict_mode);
  fun->set_context(isolate()->context()->global_context());
  return fun;
}


Handle<Object> Factory::ToObject(Handle<Object> object) {
  CALL_HEAP_FUNCTION(isolate(), object->ToObject(), Object);
}


Handle<Object> Factory::ToObject(Handle<Object> object,
                                 Handle<Context> global_context) {
  CALL_HEAP_FUNCTION(isolate(), object->ToObject(*global_context), Object);
}


#ifdef ENABLE_DEBUGGER_SUPPORT
Handle<DebugInfo> Factory::NewDebugInfo(Handle<SharedFunctionInfo> shared) {
  // Get the original code of the function.
  Handle<Code> code(shared->code());

  // Create a copy of the code before allocating the debug info object to avoid
  // allocation while setting up the debug info object.
  Handle<Code> original_code(*Factory::CopyCode(code));

  // Allocate initial fixed array for active break points before allocating the
  // debug info object to avoid allocation while setting up the debug info
  // object.
  Handle<FixedArray> break_points(
      NewFixedArray(Debug::kEstimatedNofBreakPointsInFunction));

  // Create and set up the debug info object. Debug info contains function, a
  // copy of the original code, the executing code and initial fixed array for
  // active break points.
  Handle<DebugInfo> debug_info =
      Handle<DebugInfo>::cast(NewStruct(DEBUG_INFO_TYPE));
  debug_info->set_shared(*shared);
  debug_info->set_original_code(*original_code);
  debug_info->set_code(*code);
  debug_info->set_break_points(*break_points);

  // Link debug info to function.
  shared->set_debug_info(*debug_info);

  return debug_info;
}
#endif


Handle<JSObject> Factory::NewArgumentsObject(Handle<Object> callee,
                                             int length) {
  CALL_HEAP_FUNCTION(
      isolate(),
      isolate()->heap()->AllocateArgumentsObject(*callee, length), JSObject);
}


Handle<JSFunction> Factory::CreateApiFunction(
    Handle<FunctionTemplateInfo> obj, ApiInstanceType instance_type) {
  Handle<Code> code = Handle<Code>(isolate()->builtins()->builtin(
      Builtins::HandleApiCall));
  Handle<Code> construct_stub =
      Handle<Code>(isolate()->builtins()->builtin(
          Builtins::JSConstructStubApi));

  int internal_field_count = 0;
  if (!obj->instance_template()->IsUndefined()) {
    Handle<ObjectTemplateInfo> instance_template =
        Handle<ObjectTemplateInfo>(
            ObjectTemplateInfo::cast(obj->instance_template()));
    internal_field_count =
        Smi::cast(instance_template->internal_field_count())->value();
  }

  int instance_size = kPointerSize * internal_field_count;
  InstanceType type = INVALID_TYPE;
  switch (instance_type) {
    case JavaScriptObject:
      type = JS_OBJECT_TYPE;
      instance_size += JSObject::kHeaderSize;
      break;
    case InnerGlobalObject:
      type = JS_GLOBAL_OBJECT_TYPE;
      instance_size += JSGlobalObject::kSize;
      break;
    case OuterGlobalObject:
      type = JS_GLOBAL_PROXY_TYPE;
      instance_size += JSGlobalProxy::kSize;
      break;
    default:
      break;
  }
  ASSERT(type != INVALID_TYPE);

  Handle<JSFunction> result =
      NewFunction(Factory::empty_symbol(),
                  type,
                  instance_size,
                  code,
                  true);
  // Set class name.
  Handle<Object> class_name = Handle<Object>(obj->class_name());
  if (class_name->IsString()) {
    result->shared()->set_instance_class_name(*class_name);
    result->shared()->set_name(*class_name);
  }

  Handle<Map> map = Handle<Map>(result->initial_map());

  // Mark as undetectable if needed.
  if (obj->undetectable()) {
    map->set_is_undetectable();
  }

  // Mark as hidden for the __proto__ accessor if needed.
  if (obj->hidden_prototype()) {
    map->set_is_hidden_prototype();
  }

  // Mark as needs_access_check if needed.
  if (obj->needs_access_check()) {
    map->set_is_access_check_needed(true);
  }

  // Set interceptor information in the map.
  if (!obj->named_property_handler()->IsUndefined()) {
    map->set_has_named_interceptor();
  }
  if (!obj->indexed_property_handler()->IsUndefined()) {
    map->set_has_indexed_interceptor();
  }

  // Set instance call-as-function information in the map.
  if (!obj->instance_call_handler()->IsUndefined()) {
    map->set_has_instance_call_handler();
  }

  result->shared()->set_function_data(*obj);
  result->shared()->set_construct_stub(*construct_stub);
  result->shared()->DontAdaptArguments();

  // Recursively copy parent templates' accessors, 'data' may be modified.
  Handle<DescriptorArray> array =
      Handle<DescriptorArray>(map->instance_descriptors());
  while (true) {
    Handle<Object> props = Handle<Object>(obj->property_accessors());
    if (!props->IsUndefined()) {
      array = CopyAppendCallbackDescriptors(array, props);
    }
    Handle<Object> parent = Handle<Object>(obj->parent_template());
    if (parent->IsUndefined()) break;
    obj = Handle<FunctionTemplateInfo>::cast(parent);
  }
  if (!array->IsEmpty()) {
    map->set_instance_descriptors(*array);
  }

  ASSERT(result->shared()->IsApiFunction());
  return result;
}


Handle<MapCache> Factory::NewMapCache(int at_least_space_for) {
  CALL_HEAP_FUNCTION(isolate(),
                     MapCache::Allocate(at_least_space_for), MapCache);
}


MUST_USE_RESULT static MaybeObject* UpdateMapCacheWith(Context* context,
                                                       FixedArray* keys,
                                                       Map* map) {
  Object* result;
  { MaybeObject* maybe_result =
        MapCache::cast(context->map_cache())->Put(keys, map);
    if (!maybe_result->ToObject(&result)) return maybe_result;
  }
  context->set_map_cache(MapCache::cast(result));
  return result;
}


Handle<MapCache> Factory::AddToMapCache(Handle<Context> context,
                                        Handle<FixedArray> keys,
                                        Handle<Map> map) {
  CALL_HEAP_FUNCTION(isolate(),
                     UpdateMapCacheWith(*context, *keys, *map), MapCache);
}


Handle<Map> Factory::ObjectLiteralMapFromCache(Handle<Context> context,
                                               Handle<FixedArray> keys) {
  if (context->map_cache()->IsUndefined()) {
    // Allocate the new map cache for the global context.
    Handle<MapCache> new_cache = NewMapCache(24);
    context->set_map_cache(*new_cache);
  }
  // Check to see whether there is a matching element in the cache.
  Handle<MapCache> cache =
      Handle<MapCache>(MapCache::cast(context->map_cache()));
  Handle<Object> result = Handle<Object>(cache->Lookup(*keys));
  if (result->IsMap()) return Handle<Map>::cast(result);
  // Create a new map and add it to the cache.
  Handle<Map> map =
      CopyMap(Handle<Map>(context->object_function()->initial_map()),
              keys->length());
  AddToMapCache(context, keys, map);
  return Handle<Map>(map);
}


void Factory::SetRegExpAtomData(Handle<JSRegExp> regexp,
                                JSRegExp::Type type,
                                Handle<String> source,
                                JSRegExp::Flags flags,
                                Handle<Object> data) {
  Handle<FixedArray> store = NewFixedArray(JSRegExp::kAtomDataSize);

  store->set(JSRegExp::kTagIndex, Smi::FromInt(type));
  store->set(JSRegExp::kSourceIndex, *source);
  store->set(JSRegExp::kFlagsIndex, Smi::FromInt(flags.value()));
  store->set(JSRegExp::kAtomPatternIndex, *data);
  regexp->set_data(*store);
}

void Factory::SetRegExpIrregexpData(Handle<JSRegExp> regexp,
                                    JSRegExp::Type type,
                                    Handle<String> source,
                                    JSRegExp::Flags flags,
                                    int capture_count) {
  Handle<FixedArray> store = NewFixedArray(JSRegExp::kIrregexpDataSize);

  store->set(JSRegExp::kTagIndex, Smi::FromInt(type));
  store->set(JSRegExp::kSourceIndex, *source);
  store->set(JSRegExp::kFlagsIndex, Smi::FromInt(flags.value()));
  store->set(JSRegExp::kIrregexpASCIICodeIndex, HEAP->the_hole_value());
  store->set(JSRegExp::kIrregexpUC16CodeIndex, HEAP->the_hole_value());
  store->set(JSRegExp::kIrregexpMaxRegisterCountIndex, Smi::FromInt(0));
  store->set(JSRegExp::kIrregexpCaptureCountIndex,
             Smi::FromInt(capture_count));
  regexp->set_data(*store);
}



void Factory::ConfigureInstance(Handle<FunctionTemplateInfo> desc,
                                Handle<JSObject> instance,
                                bool* pending_exception) {
  // Configure the instance by adding the properties specified by the
  // instance template.
  Handle<Object> instance_template = Handle<Object>(desc->instance_template());
  if (!instance_template->IsUndefined()) {
    Execution::ConfigureInstance(instance,
                                 instance_template,
                                 pending_exception);
  } else {
    *pending_exception = false;
  }
}


} }  // namespace v8::internal