CSE2410 Fall 2014 Bounce

// Copyright 2006-2008 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 "bootstrapper.h"

#include "compiler.h"

#include "debug.h"

#include "execution.h"

#include "global-handles.h"

#include "macro-assembler.h"

#include "natives.h"

namespace v8 { namespace internal {

// A SourceCodeCache uses a FixedArray to store pairs of

// (AsciiString*, JSFunction*), mapping names of native code files

// (runtime.js, etc.) to precompiled functions. Instead of mapping

// names to functions it might make sense to let the JS2C tool

// generate an index for each native JS file.

class SourceCodeCache BASE_EMBEDDED {

 public:

  explicit SourceCodeCache(ScriptType type): type_(type) { }

  void Initialize(bool create_heap_objects) {

    if (create_heap_objects) {

      cache_ = Heap::empty_fixed_array();

    } else {

      cache_ = NULL;

    }

  }

  void Iterate(ObjectVisitor* v) {

    v->VisitPointer(bit_cast<Object**, FixedArray**>(&cache_));

  }

  bool Lookup(Vector<const char> name, Handle<JSFunction>* handle) {

    for (int i = 0; i < cache_->length(); i+=2) {

      SeqAsciiString* str = SeqAsciiString::cast(cache_->get(i));

      if (str->IsEqualTo(name)) {

        *handle = Handle<JSFunction>(JSFunction::cast(cache_->get(i + 1)));

        return true;

      }

    }

    return false;

  }

  void Add(Vector<const char> name, Handle<JSFunction> fun) {

    ASSERT(fun->IsBoilerplate());

    HandleScope scope;

    int length = cache_->length();

    Handle<FixedArray> new_array =

        Factory::NewFixedArray(length + 2, TENURED);

    cache_->CopyTo(0, *new_array, 0, cache_->length());

    cache_ = *new_array;

    Handle<String> str = Factory::NewStringFromAscii(name, TENURED);

    cache_->set(length, *str);

    cache_->set(length + 1, *fun);

    Script::cast(fun->shared()->script())->set_type(Smi::FromInt(type_));

  }

 private:

  ScriptType type_;

  FixedArray* cache_;

  DISALLOW_COPY_AND_ASSIGN(SourceCodeCache);

};

static SourceCodeCache natives_cache(SCRIPT_TYPE_NATIVE);

static SourceCodeCache extensions_cache(SCRIPT_TYPE_EXTENSION);

Handle<String> Bootstrapper::NativesSourceLookup(int index) {

  ASSERT(0 <= index && index < Natives::GetBuiltinsCount());

  if (Heap::natives_source_cache()->get(index)->IsUndefined()) {

    Handle<String> source_code =

      Factory::NewStringFromAscii(Natives::GetScriptSource(index));

    Heap::natives_source_cache()->set(index, *source_code);

  }

  Handle<Object> cached_source(Heap::natives_source_cache()->get(index));

  return Handle<String>::cast(cached_source);

}

bool Bootstrapper::NativesCacheLookup(Vector<const char> name,

                                      Handle<JSFunction>* handle) {

  return natives_cache.Lookup(name, handle);

}

void Bootstrapper::NativesCacheAdd(Vector<const char> name,

                                   Handle<JSFunction> fun) {

  natives_cache.Add(name, fun);

}

void Bootstrapper::Initialize(bool create_heap_objects) {

  natives_cache.Initialize(create_heap_objects);

  extensions_cache.Initialize(create_heap_objects);

}

void Bootstrapper::TearDown() {

  natives_cache.Initialize(false);  // Yes, symmetrical

  extensions_cache.Initialize(false);

}

// Pending fixups are code positions that have refer to builtin code

// objects that were not available at the time the code was generated.

// The pending list is processed whenever an environment has been

// created.

class PendingFixups : public AllStatic {

 public:

  static void Add(Code* code, MacroAssembler* masm);

  static bool Process(Handle<JSBuiltinsObject> builtins);

  static void Iterate(ObjectVisitor* v);

 private:

  static List<Object*> code_;

  static List<const char*> name_;

  static List<int> pc_;

  static List<uint32_t> flags_;

  static void Clear();

};

List<Object*> PendingFixups::code_(0);

List<const char*> PendingFixups::name_(0);

List<int> PendingFixups::pc_(0);

List<uint32_t> PendingFixups::flags_(0);

void PendingFixups::Add(Code* code, MacroAssembler* masm) {

  // Note this code is not only called during bootstrapping.

  List<MacroAssembler::Unresolved>* unresolved = masm->unresolved();

  int n = unresolved->length();

  for (int i = 0; i < n; i++) {

    const char* name = unresolved->at(i).name;

    code_.Add(code);

    name_.Add(name);

    pc_.Add(unresolved->at(i).pc);

    flags_.Add(unresolved->at(i).flags);

    LOG(StringEvent("unresolved", name));

  }

}

bool PendingFixups::Process(Handle<JSBuiltinsObject> builtins) {

  HandleScope scope;

  // NOTE: Extra fixups may be added to the list during the iteration

  // due to lazy compilation of functions during the processing. Do not

  // cache the result of getting the length of the code list.

  for (int i = 0; i < code_.length(); i++) {

    const char* name = name_[i];

    uint32_t flags = flags_[i];

    Handle<String> symbol = Factory::LookupAsciiSymbol(name);

    Object* o = builtins->GetProperty(*symbol);

#ifdef DEBUG

    if (!o->IsJSFunction()) {

      V8_Fatal(__FILE__, __LINE__, "Cannot resolve call to builtin %s", name);

    }

#endif

    Handle<JSFunction> f = Handle<JSFunction>(JSFunction::cast(o));

    // Make sure the number of parameters match the formal parameter count.

    int argc = Bootstrapper::FixupFlagsArgumentsCount::decode(flags);

    USE(argc);

    ASSERT(f->shared()->formal_parameter_count() == argc);

    if (!f->is_compiled()) {

      // Do lazy compilation and check for stack overflows.

      if (!CompileLazy(f, CLEAR_EXCEPTION)) {

        Clear();

        return false;

      }

    }

    Code* code = Code::cast(code_[i]);

    Address pc = code->instruction_start() + pc_[i];

    bool is_pc_relative = Bootstrapper::FixupFlagsIsPCRelative::decode(flags);

    bool use_code_object = Bootstrapper::FixupFlagsUseCodeObject::decode(flags);

    if (use_code_object) {

      if (is_pc_relative) {

        Assembler::set_target_address_at(

            pc, reinterpret_cast<Address>(f->code()));

      } else {

        *reinterpret_cast<Object**>(pc) = f->code();

      }

    } else {

      ASSERT(is_pc_relative);

      Assembler::set_target_address_at(pc, f->code()->instruction_start());

    }

    LOG(StringEvent("resolved", name));

  }

  Clear();

  // TODO(1240818): We should probably try to avoid doing this for all

  // the V8 builtin JS files. It should only happen after running

  // runtime.js - just like there shouldn't be any fixups left after

  // that.

  for (int i = 0; i < Builtins::NumberOfJavaScriptBuiltins(); i++) {

    Builtins::JavaScript id = static_cast<Builtins::JavaScript>(i);

    Handle<String> name = Factory::LookupAsciiSymbol(Builtins::GetName(id));

    JSFunction* function = JSFunction::cast(builtins->GetProperty(*name));

    builtins->set_javascript_builtin(id, function);

  }

  return true;

}

void PendingFixups::Clear() {

  code_.Clear();

  name_.Clear();

  pc_.Clear();

  flags_.Clear();

}

void PendingFixups::Iterate(ObjectVisitor* v) {

  if (!code_.is_empty()) {

    v->VisitPointers(&code_[0], &code_[0] + code_.length());

  }

}

class Genesis BASE_EMBEDDED {

 public:

  Genesis(Handle<Object> global_object,

          v8::Handle<v8::ObjectTemplate> global_template,

          v8::ExtensionConfiguration* extensions);

  ~Genesis();

  Handle<Context> result() { return result_; }

  Genesis* previous() { return previous_; }

  static Genesis* current() { return current_; }

  // Support for thread preemption.

  static int ArchiveSpacePerThread();

  static char* ArchiveState(char* to);

  static char* RestoreState(char* from);

 private:

  Handle<Context> global_context_;

  // There may be more than one active genesis object: When GC is

  // triggered during environment creation there may be weak handle

  // processing callbacks which may create new environments.

  Genesis* previous_;

  static Genesis* current_;

  Handle<Context> global_context() { return global_context_; }

  void CreateRoots(v8::Handle<v8::ObjectTemplate> global_template,

                   Handle<Object> global_object);

  void InstallNativeFunctions();

  bool InstallNatives();

  bool InstallExtensions(v8::ExtensionConfiguration* extensions);

  bool InstallExtension(const char* name);

  bool InstallExtension(v8::RegisteredExtension* current);

  bool InstallSpecialObjects();

  bool ConfigureApiObject(Handle<JSObject> object,

                          Handle<ObjectTemplateInfo> object_template);

  bool ConfigureGlobalObjects(v8::Handle<v8::ObjectTemplate> global_template);

  // Migrates all properties from the 'from' object to the 'to'

  // object and overrides the prototype in 'to' with the one from

  // 'from'.

  void TransferObject(Handle<JSObject> from, Handle<JSObject> to);

  void TransferNamedProperties(Handle<JSObject> from, Handle<JSObject> to);

  void TransferIndexedProperties(Handle<JSObject> from, Handle<JSObject> to);

  Handle<DescriptorArray> ComputeFunctionInstanceDescriptor(

      bool make_prototype_read_only,

      bool make_prototype_enumerable = false);

  void MakeFunctionInstancePrototypeWritable();

  void AddSpecialFunction(Handle<JSObject> prototype,

                          const char* name,

                          Handle<Code> code);

  void BuildSpecialFunctionTable();

  static bool CompileBuiltin(int index);

  static bool CompileNative(Vector<const char> name, Handle<String> source);

  static bool CompileScriptCached(Vector<const char> name,

                                  Handle<String> source,

                                  SourceCodeCache* cache,

                                  v8::Extension* extension,

                                  bool use_runtime_context);

  Handle<Context> result_;

};

Genesis* Genesis::current_ = NULL;

void Bootstrapper::Iterate(ObjectVisitor* v) {

  natives_cache.Iterate(v);

  extensions_cache.Iterate(v);

  PendingFixups::Iterate(v);

}

// While setting up the environment, we collect code positions that

// need to be patched before we can run any code in the environment.

void Bootstrapper::AddFixup(Code* code, MacroAssembler* masm) {

  PendingFixups::Add(code, masm);

}

bool Bootstrapper::IsActive() {

  return Genesis::current() != NULL;

}

Handle<Context> Bootstrapper::CreateEnvironment(

    Handle<Object> global_object,

    v8::Handle<v8::ObjectTemplate> global_template,

    v8::ExtensionConfiguration* extensions) {

  Genesis genesis(global_object, global_template, extensions);

  return genesis.result();

}

static void SetObjectPrototype(Handle<JSObject> object, Handle<Object> proto) {

  // object.__proto__ = proto;

  Handle<Map> old_to_map = Handle<Map>(object->map());

  Handle<Map> new_to_map = Factory::CopyMapDropTransitions(old_to_map);

  new_to_map->set_prototype(*proto);

  object->set_map(*new_to_map);

}

void Bootstrapper::DetachGlobal(Handle<Context> env) {

  JSGlobalProxy::cast(env->global_proxy())->set_context(*Factory::null_value());

  SetObjectPrototype(Handle<JSObject>(env->global_proxy()),

                     Factory::null_value());

  env->set_global_proxy(env->global());

  env->global()->set_global_receiver(env->global());

}

Genesis::~Genesis() {

  ASSERT(current_ == this);

  current_ = previous_;

}

static Handle<JSFunction> InstallFunction(Handle<JSObject> target,

                                          const char* name,

                                          InstanceType type,

                                          int instance_size,

                                          Handle<JSObject> prototype,

                                          Builtins::Name call,

                                          bool is_ecma_native) {

  Handle<String> symbol = Factory::LookupAsciiSymbol(name);

  Handle<Code> call_code = Handle<Code>(Builtins::builtin(call));

  Handle<JSFunction> function =

    Factory::NewFunctionWithPrototype(symbol,

                                      type,

                                      instance_size,

                                      prototype,

                                      call_code,

                                      is_ecma_native);

  SetProperty(target, symbol, function, DONT_ENUM);

  if (is_ecma_native) {

    function->shared()->set_instance_class_name(*symbol);

  }

  return function;

}

Handle<DescriptorArray> Genesis::ComputeFunctionInstanceDescriptor(

    bool make_prototype_read_only,

    bool make_prototype_enumerable) {

  Handle<DescriptorArray> result = Factory::empty_descriptor_array();

  // Add prototype.

  PropertyAttributes attributes = static_cast<PropertyAttributes>(

      (make_prototype_enumerable ? 0 : DONT_ENUM)

      | DONT_DELETE

      | (make_prototype_read_only ? READ_ONLY : 0));

  result =

      Factory::CopyAppendProxyDescriptor(

          result,

          Factory::prototype_symbol(),

          Factory::NewProxy(&Accessors::FunctionPrototype),

          attributes);

  attributes =

      static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE | READ_ONLY);

  // Add length.

  result =

      Factory::CopyAppendProxyDescriptor(

          result,

          Factory::length_symbol(),

          Factory::NewProxy(&Accessors::FunctionLength),

          attributes);

  // Add name.

  result =

      Factory::CopyAppendProxyDescriptor(

          result,

          Factory::name_symbol(),

          Factory::NewProxy(&Accessors::FunctionName),

          attributes);

  // Add arguments.

  result =

      Factory::CopyAppendProxyDescriptor(

          result,

          Factory::arguments_symbol(),

          Factory::NewProxy(&Accessors::FunctionArguments),

          attributes);

  // Add caller.

  result =

      Factory::CopyAppendProxyDescriptor(

          result,

          Factory::caller_symbol(),

          Factory::NewProxy(&Accessors::FunctionCaller),

          attributes);

  return result;

}

void Genesis::CreateRoots(v8::Handle<v8::ObjectTemplate> global_template,

                          Handle<Object> global_object) {

  HandleScope scope;

  // Allocate the global context FixedArray first and then patch the

  // closure and extension object later (we need the empty function

  // and the global object, but in order to create those, we need the

  // global context).

  global_context_ =

      Handle<Context>::cast(

          GlobalHandles::Create(*Factory::NewGlobalContext()));

  Top::set_context(*global_context());

  // Allocate the message listeners object.

  v8::NeanderArray listeners;

  global_context()->set_message_listeners(*listeners.value());

  // Allocate the map for function instances.

  Handle<Map> fm = Factory::NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);

  global_context()->set_function_instance_map(*fm);

  // Please note that the prototype property for function instances must be

  // writable.

  Handle<DescriptorArray> function_map_descriptors =

      ComputeFunctionInstanceDescriptor(false, true);

  fm->set_instance_descriptors(*function_map_descriptors);

  // Allocate the function map first and then patch the prototype later

  fm = Factory::NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);

  global_context()->set_function_map(*fm);

  function_map_descriptors = ComputeFunctionInstanceDescriptor(true);

  fm->set_instance_descriptors(*function_map_descriptors);

  Handle<String> object_name = Handle<String>(Heap::Object_symbol());

  {  // --- O b j e c t ---

    Handle<JSFunction> object_fun =

        Factory::NewFunction(object_name, Factory::null_value());

    Handle<Map> object_function_map =

        Factory::NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);

    object_fun->set_initial_map(*object_function_map);

    object_function_map->set_constructor(*object_fun);

    global_context()->set_object_function(*object_fun);

    // Allocate a new prototype for the object function.

    Handle<JSObject> prototype = Factory::NewJSObject(Top::object_function(),

                                                      TENURED);

    global_context()->set_initial_object_prototype(*prototype);

    SetPrototype(object_fun, prototype);

    object_function_map->

      set_instance_descriptors(Heap::empty_descriptor_array());

  }

  // Allocate the empty function as the prototype for function ECMAScript

  // 262 15.3.4.

  Handle<String> symbol = Factory::LookupAsciiSymbol("Empty");

  Handle<JSFunction> empty_function =

      Factory::NewFunction(symbol, Factory::null_value());

  {  // --- E m p t y ---

    Handle<Code> code =

        Handle<Code>(Builtins::builtin(Builtins::EmptyFunction));

    empty_function->set_code(*code);

    Handle<String> source = Factory::NewStringFromAscii(CStrVector("() {}"));

    Handle<Script> script = Factory::NewScript(source);

    script->set_type(Smi::FromInt(SCRIPT_TYPE_NATIVE));

    empty_function->shared()->set_script(*script);

    empty_function->shared()->set_start_position(0);

    empty_function->shared()->set_end_position(source->length());

    empty_function->shared()->DontAdaptArguments();

    global_context()->function_map()->set_prototype(*empty_function);

    global_context()->function_instance_map()->set_prototype(*empty_function);

    // Allocate the function map first and then patch the prototype later

    Handle<Map> empty_fm = Factory::CopyMap(fm);

    empty_fm->set_instance_descriptors(*function_map_descriptors);

    empty_fm->set_prototype(global_context()->object_function()->prototype());

    empty_function->set_map(*empty_fm);

  }

  {  // --- G l o b a l ---

    // Step 1: create a fresh inner JSGlobalObject

    Handle<JSGlobalObject> object;

    {

      Handle<JSFunction> js_global_function;

      Handle<ObjectTemplateInfo> js_global_template;

      if (!global_template.IsEmpty()) {

        // Get prototype template of the global_template

        Handle<ObjectTemplateInfo> data =

            v8::Utils::OpenHandle(*global_template);

        Handle<FunctionTemplateInfo> global_constructor =

            Handle<FunctionTemplateInfo>(

                FunctionTemplateInfo::cast(data->constructor()));

        Handle<Object> proto_template(global_constructor->prototype_template());

        if (!proto_template->IsUndefined()) {

          js_global_template =

              Handle<ObjectTemplateInfo>::cast(proto_template);

        }

      }

      if (js_global_template.is_null()) {

        Handle<String> name = Handle<String>(Heap::empty_symbol());

        Handle<Code> code = Handle<Code>(Builtins::builtin(Builtins::Illegal));

        js_global_function =

            Factory::NewFunction(name, JS_GLOBAL_OBJECT_TYPE,

                                 JSGlobalObject::kSize, code, true);

        // Change the constructor property of the prototype of the

        // hidden global function to refer to the Object function.

        Handle<JSObject> prototype =

            Handle<JSObject>(

                JSObject::cast(js_global_function->instance_prototype()));

        SetProperty(prototype, Factory::constructor_symbol(),

                    Top::object_function(), NONE);

      } else {

        Handle<FunctionTemplateInfo> js_global_constructor(

            FunctionTemplateInfo::cast(js_global_template->constructor()));

        js_global_function =

            Factory::CreateApiFunction(js_global_constructor,

                                       Factory::InnerGlobalObject);

      }

      js_global_function->initial_map()->set_is_hidden_prototype();

      SetExpectedNofProperties(js_global_function, 100);

      object = Handle<JSGlobalObject>::cast(

          Factory::NewJSObject(js_global_function, TENURED));

    }

    // Set the global context for the global object.

    object->set_global_context(*global_context());

    // Step 2: create or re-initialize the global proxy object.

    Handle<JSGlobalProxy> global_proxy;

    {

      Handle<JSFunction> global_proxy_function;

      if (global_template.IsEmpty()) {

        Handle<String> name = Handle<String>(Heap::empty_symbol());

        Handle<Code> code = Handle<Code>(Builtins::builtin(Builtins::Illegal));

        global_proxy_function =

            Factory::NewFunction(name, JS_GLOBAL_PROXY_TYPE,

                                 JSGlobalProxy::kSize, code, true);

      } else {

        Handle<ObjectTemplateInfo> data =

            v8::Utils::OpenHandle(*global_template);

        Handle<FunctionTemplateInfo> global_constructor(

                FunctionTemplateInfo::cast(data->constructor()));

        global_proxy_function =

            Factory::CreateApiFunction(global_constructor,

                                       Factory::OuterGlobalObject);

      }

      Handle<String> global_name = Factory::LookupAsciiSymbol("global");

      global_proxy_function->shared()->set_instance_class_name(*global_name);

      global_proxy_function->initial_map()->set_is_access_check_needed(true);

      // Set global_proxy.__proto__ to js_global after ConfigureGlobalObjects

      if (global_object.location() != NULL) {

        ASSERT(global_object->IsJSGlobalProxy());

        global_proxy =

            ReinitializeJSGlobalProxy(

                global_proxy_function,

                Handle<JSGlobalProxy>::cast(global_object));

      } else {

        global_proxy = Handle<JSGlobalProxy>::cast(

            Factory::NewJSObject(global_proxy_function, TENURED));

      }

      // Security setup: Set the security token of the global object to

      // its the inner global. This makes the security check between two

      // different contexts fail by default even in case of global

      // object reinitialization.

      object->set_global_receiver(*global_proxy);

      global_proxy->set_context(*global_context());

    }

    {  // --- G l o b a l   C o n t e x t ---

      // use the empty function as closure (no scope info)

      global_context()->set_closure(*empty_function);

      global_context()->set_fcontext(*global_context());

      global_context()->set_previous(NULL);

      // set extension and global object

      global_context()->set_extension(*object);

      global_context()->set_global(*object);

      global_context()->set_global_proxy(*global_proxy);

      // use inner global object as security token by default

      global_context()->set_security_token(*object);

    }

    Handle<JSObject> global = Handle<JSObject>(global_context()->global());

    SetProperty(global, object_name, Top::object_function(), DONT_ENUM);

  }

  Handle<JSObject> global = Handle<JSObject>(global_context()->global());

  // Install global Function object

  InstallFunction(global, "Function", JS_FUNCTION_TYPE, JSFunction::kSize,

                  empty_function, Builtins::Illegal, true);  // ECMA native.

  {  // --- A r r a y ---

    Handle<JSFunction> array_function =

        InstallFunction(global, "Array", JS_ARRAY_TYPE, JSArray::kSize,

                        Top::initial_object_prototype(), Builtins::ArrayCode,

                        true);

    array_function->shared()->DontAdaptArguments();

    // This seems a bit hackish, but we need to make sure Array.length

    // is 1.

    array_function->shared()->set_length(1);

    Handle<DescriptorArray> array_descriptors =

        Factory::CopyAppendProxyDescriptor(

            Factory::empty_descriptor_array(),

            Factory::length_symbol(),

            Factory::NewProxy(&Accessors::ArrayLength),

            static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE));

    // Cache the fast JavaScript array map

    global_context()->set_js_array_map(array_function->initial_map());

    global_context()->js_array_map()->set_instance_descriptors(

        *array_descriptors);

    // array_function is used internally. JS code creating array object should

    // search for the 'Array' property on the global object and use that one

    // as the constructor. 'Array' property on a global object can be

    // overwritten by JS code.

    global_context()->set_array_function(*array_function);

  }

  {  // --- N u m b e r ---

    Handle<JSFunction> number_fun =

        InstallFunction(global, "Number", JS_VALUE_TYPE, JSValue::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        true);

    global_context()->set_number_function(*number_fun);

  }

  {  // --- B o o l e a n ---

    Handle<JSFunction> boolean_fun =

        InstallFunction(global, "Boolean", JS_VALUE_TYPE, JSValue::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        true);

    global_context()->set_boolean_function(*boolean_fun);

  }

  {  // --- S t r i n g ---

    Handle<JSFunction> string_fun =

        InstallFunction(global, "String", JS_VALUE_TYPE, JSValue::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        true);

    global_context()->set_string_function(*string_fun);

    // Add 'length' property to strings.

    Handle<DescriptorArray> string_descriptors =

        Factory::CopyAppendProxyDescriptor(

            Factory::empty_descriptor_array(),

            Factory::length_symbol(),

            Factory::NewProxy(&Accessors::StringLength),

            static_cast<PropertyAttributes>(DONT_ENUM |

                                            DONT_DELETE |

                                            READ_ONLY));

    Handle<Map> string_map =

        Handle<Map>(global_context()->string_function()->initial_map());

    string_map->set_instance_descriptors(*string_descriptors);

  }

  {  // --- D a t e ---

    // Builtin functions for Date.prototype.

    Handle<JSFunction> date_fun =

        InstallFunction(global, "Date", JS_VALUE_TYPE, JSValue::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        true);

    global_context()->set_date_function(*date_fun);

  }

  {  // -- R e g E x p

    // Builtin functions for RegExp.prototype.

    Handle<JSFunction> regexp_fun =

        InstallFunction(global, "RegExp", JS_REGEXP_TYPE, JSRegExp::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        true);

    global_context()->set_regexp_function(*regexp_fun);

  }

  {  // --- arguments_boilerplate_

    // Make sure we can recognize argument objects at runtime.

    // This is done by introducing an anonymous function with

    // class_name equals 'Arguments'.

    Handle<String> symbol = Factory::LookupAsciiSymbol("Arguments");

    Handle<Code> code = Handle<Code>(Builtins::builtin(Builtins::Illegal));

    Handle<JSObject> prototype =

        Handle<JSObject>(

            JSObject::cast(global_context()->object_function()->prototype()));

    Handle<JSFunction> function =

        Factory::NewFunctionWithPrototype(symbol,

                                          JS_OBJECT_TYPE,

                                          JSObject::kHeaderSize,

                                          prototype,

                                          code,

                                          false);

    ASSERT(!function->has_initial_map());

    function->shared()->set_instance_class_name(*symbol);

    function->shared()->set_expected_nof_properties(2);

    Handle<JSObject> result = Factory::NewJSObject(function);

    global_context()->set_arguments_boilerplate(*result);

    // Note: callee must be added as the first property and

    //       length must be added as the second property.

    SetProperty(result, Factory::callee_symbol(),

                Factory::undefined_value(),

                DONT_ENUM);

    SetProperty(result, Factory::length_symbol(),

                Factory::undefined_value(),

                DONT_ENUM);

#ifdef DEBUG

    LookupResult lookup;

    result->LocalLookup(Heap::callee_symbol(), &lookup);

    ASSERT(lookup.IsValid() && (lookup.type() == FIELD));

    ASSERT(lookup.GetFieldIndex() == Heap::arguments_callee_index);

    result->LocalLookup(Heap::length_symbol(), &lookup);

    ASSERT(lookup.IsValid() && (lookup.type() == FIELD));

    ASSERT(lookup.GetFieldIndex() == Heap::arguments_length_index);

    ASSERT(result->map()->inobject_properties() > Heap::arguments_callee_index);

    ASSERT(result->map()->inobject_properties() > Heap::arguments_length_index);

    // Check the state of the object.

    ASSERT(result->HasFastProperties());

    ASSERT(result->HasFastElements());

#endif

  }

  {  // --- context extension

    // Create a function for the context extension objects.

    Handle<Code> code = Handle<Code>(Builtins::builtin(Builtins::Illegal));

    Handle<JSFunction> context_extension_fun =

        Factory::NewFunction(Factory::empty_symbol(),

                             JS_CONTEXT_EXTENSION_OBJECT_TYPE,

                             JSObject::kHeaderSize,

                             code,

                             true);

    Handle<String> name = Factory::LookupAsciiSymbol("context_extension");

    context_extension_fun->shared()->set_instance_class_name(*name);

    global_context()->set_context_extension_function(*context_extension_fun);

  }

  // Setup the call-as-function delegate.

  Handle<Code> code =

      Handle<Code>(Builtins::builtin(Builtins::HandleApiCallAsFunction));

  Handle<JSFunction> delegate =

      Factory::NewFunction(Factory::empty_symbol(), JS_OBJECT_TYPE,

                           JSObject::kHeaderSize, code, true);

  global_context()->set_call_as_function_delegate(*delegate);

  delegate->shared()->DontAdaptArguments();

  global_context()->set_special_function_table(Heap::empty_fixed_array());

  // Initialize the out of memory slot.

  global_context()->set_out_of_memory(Heap::false_value());

}

bool Genesis::CompileBuiltin(int index) {

  Vector<const char> name = Natives::GetScriptName(index);

  Handle<String> source_code = Bootstrapper::NativesSourceLookup(index);

  return CompileNative(name, source_code);

}

bool Genesis::CompileNative(Vector<const char> name, Handle<String> source) {

  HandleScope scope;

  Debugger::set_compiling_natives(true);

  bool result =

      CompileScriptCached(name, source, &natives_cache, NULL, true);

  ASSERT(Top::has_pending_exception() != result);

  if (!result) Top::clear_pending_exception();

  Debugger::set_compiling_natives(false);

  return result;

}

bool Genesis::CompileScriptCached(Vector<const char> name,

                                  Handle<String> source,

                                  SourceCodeCache* cache,

                                  v8::Extension* extension,

                                  bool use_runtime_context) {

  HandleScope scope;

  Handle<JSFunction> boilerplate;

  // If we can't find the function in the cache, we compile a new

  // function and insert it into the cache.

  if (!cache->Lookup(name, &boilerplate)) {

#ifdef DEBUG

    ASSERT(StringShape(*source).IsAsciiRepresentation());

#endif

    Handle<String> script_name = Factory::NewStringFromUtf8(name);

    boilerplate =

        Compiler::Compile(source, script_name, 0, 0, extension, NULL);

    if (boilerplate.is_null()) return false;

    cache->Add(name, boilerplate);

  }

  // Setup the function context. Conceptually, we should clone the

  // function before overwriting the context but since we're in a

  // single-threaded environment it is not strictly necessary.

  ASSERT(Top::context()->IsGlobalContext());

  Handle<Context> context =

      Handle<Context>(use_runtime_context

                      ? Top::context()->runtime_context()

                      : Top::context());

  Handle<JSFunction> fun =

      Factory::NewFunctionFromBoilerplate(boilerplate, context);

  // Call function using the either the runtime object or the global

  // object as the receiver. Provide no parameters.

  Handle<Object> receiver =

      Handle<Object>(use_runtime_context

                     ? Top::context()->builtins()

                     : Top::context()->global());

  bool has_pending_exception;

  Handle<Object> result =

      Execution::Call(fun, receiver, 0, NULL, &has_pending_exception);

  if (has_pending_exception) return false;

  return PendingFixups::Process(

      Handle<JSBuiltinsObject>(Top::context()->builtins()));

}

#define INSTALL_NATIVE(Type, name, var)                                  \

  Handle<String> var##_name = Factory::LookupAsciiSymbol(name);          \

  global_context()->set_##var(Type::cast(global_context()->              \

                                           builtins()->                  \

                                             GetProperty(*var##_name)));

void Genesis::InstallNativeFunctions() {

  HandleScope scope;

  INSTALL_NATIVE(JSFunction, "CreateDate", create_date_fun);

  INSTALL_NATIVE(JSFunction, "ToNumber", to_number_fun);

  INSTALL_NATIVE(JSFunction, "ToString", to_string_fun);

  INSTALL_NATIVE(JSFunction, "ToDetailString", to_detail_string_fun);

  INSTALL_NATIVE(JSFunction, "ToObject", to_object_fun);

  INSTALL_NATIVE(JSFunction, "ToInteger", to_integer_fun);

  INSTALL_NATIVE(JSFunction, "ToUint32", to_uint32_fun);

  INSTALL_NATIVE(JSFunction, "ToInt32", to_int32_fun);

  INSTALL_NATIVE(JSFunction, "ToBoolean", to_boolean_fun);

  INSTALL_NATIVE(JSFunction, "Instantiate", instantiate_fun);

  INSTALL_NATIVE(JSFunction, "ConfigureTemplateInstance",

                 configure_instance_fun);

  INSTALL_NATIVE(JSFunction, "MakeMessage", make_message_fun);

  INSTALL_NATIVE(JSFunction, "GetStackTraceLine", get_stack_trace_line_fun);

  INSTALL_NATIVE(JSObject, "functionCache", function_cache);

}

#undef INSTALL_NATIVE

bool Genesis::InstallNatives() {

  HandleScope scope;

  // Create a function for the builtins object. Allocate space for the

  // JavaScript builtins, a reference to the builtins object

  // (itself) and a reference to the global_context directly in the object.

  Handle<Code> code = Handle<Code>(Builtins::builtin(Builtins::Illegal));

  Handle<JSFunction> builtins_fun =

      Factory::NewFunction(Factory::empty_symbol(), JS_BUILTINS_OBJECT_TYPE,

                           JSBuiltinsObject::kSize, code, true);

  Handle<String> name = Factory::LookupAsciiSymbol("builtins");

  builtins_fun->shared()->set_instance_class_name(*name);

  SetExpectedNofProperties(builtins_fun, 100);

  // Allocate the builtins object.

  Handle<JSBuiltinsObject> builtins =

      Handle<JSBuiltinsObject>::cast(Factory::NewJSObject(builtins_fun,

                                                          TENURED));

  builtins->set_builtins(*builtins);

  builtins->set_global_context(*global_context());

  builtins->set_global_receiver(*builtins);

  // Setup the 'global' properties of the builtins object. The

  // 'global' property that refers to the global object is the only

  // way to get from code running in the builtins context to the

  // global object.

  static const PropertyAttributes attributes =

      static_cast<PropertyAttributes>(READ_ONLY | DONT_DELETE);

  SetProperty(builtins, Factory::LookupAsciiSymbol("global"),

              Handle<Object>(global_context()->global()), attributes);

  // Setup the reference from the global object to the builtins object.

  JSGlobalObject::cast(global_context()->global())->set_builtins(*builtins);

  // Create a bridge function that has context in the global context.

  Handle<JSFunction> bridge =

      Factory::NewFunction(Factory::empty_symbol(), Factory::undefined_value());

  ASSERT(bridge->context() == *Top::global_context());

  // Allocate the builtins context.

  Handle<Context> context =

    Factory::NewFunctionContext(Context::MIN_CONTEXT_SLOTS, bridge);

  context->set_global(*builtins);  // override builtins global object

  global_context()->set_runtime_context(*context);

  {  // -- S c r i p t

    // Builtin functions for Script.

    Handle<JSFunction> script_fun =

        InstallFunction(builtins, "Script", JS_VALUE_TYPE, JSValue::kSize,

                        Top::initial_object_prototype(), Builtins::Illegal,

                        false);

    Handle<JSObject> prototype =

        Factory::NewJSObject(Top::object_function(), TENURED);

    SetPrototype(script_fun, prototype);

    global_context()->set_script_function(*script_fun);

    // Add 'source' and 'data' property to scripts.

    PropertyAttributes common_attributes =

        static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE | READ_ONLY);

    Handle<Proxy> proxy_source = Factory::NewProxy(&Accessors::ScriptSource);

    Handle<DescriptorArray> script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            Factory::empty_descriptor_array(),

            Factory::LookupAsciiSymbol("source"),

            proxy_source,

            common_attributes);

    Handle<Proxy> proxy_name = Factory::NewProxy(&Accessors::ScriptName);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("name"),

            proxy_name,

            common_attributes);

    Handle<Proxy> proxy_id = Factory::NewProxy(&Accessors::ScriptId);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("id"),

            proxy_id,

            common_attributes);

    Handle<Proxy> proxy_line_offset =

        Factory::NewProxy(&Accessors::ScriptLineOffset);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("line_offset"),

            proxy_line_offset,

            common_attributes);

    Handle<Proxy> proxy_column_offset =

        Factory::NewProxy(&Accessors::ScriptColumnOffset);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("column_offset"),

            proxy_column_offset,

            common_attributes);

    Handle<Proxy> proxy_type = Factory::NewProxy(&Accessors::ScriptType);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("type"),

            proxy_type,

            common_attributes);

    Handle<Proxy> proxy_line_ends =

        Factory::NewProxy(&Accessors::ScriptLineEnds);

    script_descriptors =

        Factory::CopyAppendProxyDescriptor(

            script_descriptors,

            Factory::LookupAsciiSymbol("line_ends"),

            proxy_line_ends,

            common_attributes);

    Handle<Map> script_map = Handle<Map>(script_fun->initial_map());

    script_map->set_instance_descriptors(*script_descriptors);

    // Allocate the empty script.

    Handle<Script> script = Factory::NewScript(Factory::empty_string());

    script->set_type(Smi::FromInt(SCRIPT_TYPE_NATIVE));

    global_context()->set_empty_script(*script);

  }

  if (FLAG_natives_file == NULL) {

    // Without natives file, install default natives.

    for (int i = Natives::GetDelayCount();

         i < Natives::GetBuiltinsCount();

         i++) {

      if (!CompileBuiltin(i)) return false;

    }

    // Setup natives with lazy loading.

    SetupLazy(Handle<JSFunction>(global_context()->date_function()),

              Natives::GetIndex("date"),

              Top::global_context(),

              Handle<Context>(Top::context()->runtime_context()));

    SetupLazy(Handle<JSFunction>(global_context()->regexp_function()),

              Natives::GetIndex("regexp"),

              Top::global_context(),

              Handle<Context>(Top::context()->runtime_context()));

  } else if (strlen(FLAG_natives_file) != 0) {

    // Otherwise install natives from natives file if file exists and

    // compiles.

    bool exists;

    Vector<const char> source = ReadFile(FLAG_natives_file, &exists);

    Handle<String> source_string = Factory::NewStringFromAscii(source);

    if (source.is_empty()) return false;

    bool result = CompileNative(CStrVector(FLAG_natives_file), source_string);

    if (!result) return false;

  } else {

    // Empty natives file name - do not install any natives.

    PrintF("Warning: Running without installed natives!\n");

    return true;

  }

  InstallNativeFunctions();

  // Install Function.prototype.call and apply.

  { Handle<String> key = Factory::function_class_symbol();

    Handle<JSFunction> function =

        Handle<JSFunction>::cast(GetProperty(Top::global(), key));

    Handle<JSObject> proto =

        Handle<JSObject>(JSObject::cast(function->instance_prototype()));

    // Install the call and the apply functions.

    Handle<JSFunction> call =

        InstallFunction(proto, "call", JS_OBJECT_TYPE, JSObject::kHeaderSize,

                        Factory::NewJSObject(Top::object_function(), TENURED),

                        Builtins::FunctionCall,

                        false);

    Handle<JSFunction> apply =

        InstallFunction(proto, "apply", JS_OBJECT_TYPE, JSObject::kHeaderSize,

                        Factory::NewJSObject(Top::object_function(), TENURED),

                        Builtins::FunctionApply,

                        false);

    // Make sure that Function.prototype.call appears to be compiled.

    // The code will never be called, but inline caching for call will

    // only work if it appears to be compiled.

    call->shared()->DontAdaptArguments();

    ASSERT(call->is_compiled());

    // Set the expected parameters for apply to 2; required by builtin.

    apply->shared()->set_formal_parameter_count(2);

    // Set the lengths for the functions to satisfy ECMA-262.

    call->shared()->set_length(1);

    apply->shared()->set_length(2);

  }

  // Make sure that the builtins object has fast properties.

  // If the ASSERT below fails, please increase the expected number of

  // properties for the builtins object.

  ASSERT(builtins->HasFastProperties());

#ifdef DEBUG

  builtins->Verify();

#endif

  return true;

}

bool Genesis::InstallSpecialObjects() {

  HandleScope scope;

  Handle<JSGlobalObject> js_global(

      JSGlobalObject::cast(global_context()->global()));

  // Expose the natives in global if a name for it is specified.

  if (FLAG_expose_natives_as != NULL && strlen(FLAG_expose_natives_as) != 0) {

    Handle<String> natives_string =

        Factory::LookupAsciiSymbol(FLAG_expose_natives_as);

    SetProperty(js_global, natives_string,

                Handle<JSObject>(js_global->builtins()), DONT_ENUM);

  }

  // Expose the debug global object in global if a name for it is specified.

  if (FLAG_expose_debug_as != NULL && strlen(FLAG_expose_debug_as) != 0) {

    // If loading fails we just bail out without installing the

    // debugger but without tanking the whole context.

    if (!Debug::Load())

      return true;

    // Set the security token for the debugger context to the same as

    // the shell global context to allow calling between these (otherwise

    // exposing debug global object doesn't make much sense).

    Debug::debug_context()->set_security_token(

        global_context()->security_token());

    Handle<String> debug_string =

        Factory::LookupAsciiSymbol(FLAG_expose_debug_as);

    SetProperty(js_global, debug_string,

        Handle<Object>(Debug::debug_context()->global_proxy()), DONT_ENUM);

  }

  return true;

}

bool Genesis::InstallExtensions(v8::ExtensionConfiguration* extensions) {

  // Clear coloring of extension list

  v8::RegisteredExtension* current = v8::RegisteredExtension::first_extension();

  while (current != NULL) {

    current->set_state(v8::UNVISITED);

    current = current->next();

  }

  // Install auto extensions

  current = v8::RegisteredExtension::first_extension();

  while (current != NULL) {

    if (current->extension()->auto_enable())

      InstallExtension(current);

    current = current->next();

  }

  if (FLAG_expose_gc) InstallExtension("v8/gc");

  if (extensions == NULL) return true;

  // Install required extensions

  int count = v8::ImplementationUtilities::GetNameCount(extensions);

  const char** names = v8::ImplementationUtilities::GetNames(extensions);

  for (int i = 0; i < count; i++) {

    if (!InstallExtension(names[i]))

      return false;

  }

  return true;

}

// Installs a named extension.  This methods is unoptimized and does

// not scale well if we want to support a large number of extensions.

bool Genesis::InstallExtension(const char* name) {

  v8::RegisteredExtension* current = v8::RegisteredExtension::first_extension();

  // Loop until we find the relevant extension

  while (current != NULL) {

    if (strcmp(name, current->extension()->name()) == 0) break;

    current = current->next();

  }

  // Didn't find the extension; fail.

  if (current == NULL) {

    v8::Utils::ReportApiFailure(

        "v8::Context::New()", "Cannot find required extension");

    return false;

  }

  return InstallExtension(current);

}

bool Genesis::InstallExtension(v8::RegisteredExtension* current) {

  HandleScope scope;

  if (current->state() == v8::INSTALLED) return true;

  // The current node has already been visited so there must be a

  // cycle in the dependency graph; fail.

  if (current->state() == v8::VISITED) {

    v8::Utils::ReportApiFailure(

        "v8::Context::New()", "Circular extension dependency");

    return false;

  }

  ASSERT(current->state() == v8::UNVISITED);

  current->set_state(v8::VISITED);

  v8::Extension* extension = current->extension();

  // Install the extension's dependencies

  for (int i = 0; i < extension->dependency_count(); i++) {

    if (!InstallExtension(extension->dependencies()[i])) return false;

  }

  Vector<const char> source = CStrVector(extension->source());

  Handle<String> source_code = Factory::NewStringFromAscii(source);

  bool result = CompileScriptCached(CStrVector(extension->name()),

                                    source_code,

                                    &extensions_cache, extension,

                                    false);

  ASSERT(Top::has_pending_exception() != result);

  if (!result) {

    Top::clear_pending_exception();

    v8::Utils::ReportApiFailure(

        "v8::Context::New()", "Error installing extension");

  }

  current->set_state(v8::INSTALLED);

  return result;

}

bool Genesis::ConfigureGlobalObjects(

    v8::Handle<v8::ObjectTemplate> global_proxy_template) {

  Handle<JSObject> global_proxy(

      JSObject::cast(global_context()->global_proxy()));

  Handle<JSObject> js_global(JSObject::cast(global_context()->global()));

  if (!global_proxy_template.IsEmpty()) {

    // Configure the global proxy object.

    Handle<ObjectTemplateInfo> proxy_data =

        v8::Utils::OpenHandle(*global_proxy_template);

    if (!ConfigureApiObject(global_proxy, proxy_data)) return false;

    // Configure the inner global object.

    Handle<FunctionTemplateInfo> proxy_constructor(

        FunctionTemplateInfo::cast(proxy_data->constructor()));

    if (!proxy_constructor->prototype_template()->IsUndefined()) {

      Handle<ObjectTemplateInfo> inner_data(

          ObjectTemplateInfo::cast(proxy_constructor->prototype_template()));

      if (!ConfigureApiObject(js_global, inner_data)) return false;

    }

  }

  SetObjectPrototype(global_proxy, js_global);

  return true;

}

bool Genesis::ConfigureApiObject(Handle<JSObject> object,

    Handle<ObjectTemplateInfo> object_template) {

  ASSERT(!object_template.is_null());

  ASSERT(object->IsInstanceOf(

      FunctionTemplateInfo::cast(object_template->constructor())));

  bool pending_exception = false;

  Handle<JSObject> obj =

      Execution::InstantiateObject(object_template, &pending_exception);

  if (pending_exception) {

    ASSERT(Top::has_pending_exception());

    Top::clear_pending_exception();

    return false;

  }

  TransferObject(obj, object);

  return true;

}

void Genesis::TransferNamedProperties(Handle<JSObject> from,

                                      Handle<JSObject> to) {

  if (from->HasFastProperties()) {

    Handle<DescriptorArray> descs =

        Handle<DescriptorArray>(from->map()->instance_descriptors());

    int offset = 0;

    while (true) {

      // Iterating through the descriptors is not gc safe so we have to

      // store the value in a handle and create a new stream for each entry.

      DescriptorReader stream(*descs, offset);

      if (stream.eos()) break;

      // We have to read out the next offset before we do anything that may

      // cause a gc, since the DescriptorReader is not gc safe.

      offset = stream.next_position();

      PropertyDetails details = stream.GetDetails();

      switch (details.type()) {

        case FIELD: {

          HandleScope inner;

          Handle<String> key = Handle<String>(stream.GetKey());

          int index = stream.GetFieldIndex();

          Handle<Object> value = Handle<Object>(from->FastPropertyAt(index));

          SetProperty(to, key, value, details.attributes());

          break;

        }

        case CONSTANT_FUNCTION: {

          HandleScope inner;

          Handle<String> key = Handle<String>(stream.GetKey());

          Handle<JSFunction> fun =

              Handle<JSFunction>(stream.GetConstantFunction());

          SetProperty(to, key, fun, details.attributes());

          break;

        }

        case CALLBACKS: {

          LookupResult result;

          to->LocalLookup(stream.GetKey(), &result);

          // If the property is already there we skip it

          if (result.IsValid()) continue;

          HandleScope inner;

          Handle<DescriptorArray> inst_descs =

              Handle<DescriptorArray>(to->map()->instance_descriptors());

          Handle<String> key = Handle<String>(stream.GetKey());

          Handle<Object> entry = Handle<Object>(stream.GetCallbacksObject());

          inst_descs = Factory::CopyAppendProxyDescriptor(inst_descs,

                                                          key,

                                                          entry,

                                                          details.attributes());

          to->map()->set_instance_descriptors(*inst_descs);

          break;

        }

        case MAP_TRANSITION:

        case CONSTANT_TRANSITION:

        case NULL_DESCRIPTOR:

          // Ignore non-properties.

          break;

        case NORMAL:

          // Do not occur since the from object has fast properties.

        case INTERCEPTOR:

          // No element in instance descriptors have interceptor type.

          UNREACHABLE();

          break;

      }

    }

  } else {

    Handle<Dictionary> properties =

        Handle<Dictionary>(from->property_dictionary());

    int capacity = properties->Capacity();

    for (int i = 0; i < capacity; i++) {

      Object* raw_key(properties->KeyAt(i));

      if (properties->IsKey(raw_key)) {

        ASSERT(raw_key->IsString());

        // If the property is already there we skip it.

        LookupResult result;

        to->LocalLookup(String::cast(raw_key), &result);

        if (result.IsValid()) continue;

        // Set the property.

        Handle<String> key = Handle<String>(String::cast(raw_key));

        Handle<Object> value = Handle<Object>(properties->ValueAt(i));

        PropertyDetails details = properties->DetailsAt(i);

        SetProperty(to, key, value, details.attributes());

      }

    }

  }

}

void Genesis::TransferIndexedProperties(Handle<JSObject> from,

                                        Handle<JSObject> to) {

  // Cloning the elements array is sufficient.

  Handle<FixedArray> from_elements =

      Handle<FixedArray>(FixedArray::cast(from->elements()));

  Handle<FixedArray> to_elements = Factory::CopyFixedArray(from_elements);

  to->set_elements(*to_elements);

}

void Genesis::TransferObject(Handle<JSObject> from, Handle<JSObject> to) {

  HandleScope outer;

  ASSERT(!from->IsJSArray());

  ASSERT(!to->IsJSArray());

  TransferNamedProperties(from, to);

  TransferIndexedProperties(from, to);

  // Transfer the prototype (new map is needed).

  Handle<Map> old_to_map = Handle<Map>(to->map());

  Handle<Map> new_to_map = Factory::CopyMapDropTransitions(old_to_map);

  new_to_map->set_prototype(from->map()->prototype());

  to->set_map(*new_to_map);

}

void Genesis::MakeFunctionInstancePrototypeWritable() {

  // Make a new function map so all future functions

  // will have settable and enumerable prototype properties.

  HandleScope scope;

  Handle<DescriptorArray> function_map_descriptors =

      ComputeFunctionInstanceDescriptor(false, true);

  Handle<Map> fm = Factory::CopyMap(Top::function_map());

  fm->set_instance_descriptors(*function_map_descriptors);

  Top::context()->global_context()->set_function_map(*fm);

}

void Genesis::AddSpecialFunction(Handle<JSObject> prototype,

                                 const char* name,