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Make Empty function to have no prototype and use it as __proto__ for all functions without prototype.

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Review URL: http://codereview.chromium.org/1769013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4544 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
dgozman@chromium.org 2010-04-29 10:39:36 +00:00
parent 22a8a1e770
commit a0c1310479
2 changed files with 16 additions and 34 deletions
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45
src/bootstrapper.cc
View File

@ -418,12 +418,15 @@ Handle<JSFunction> Genesis::CreateEmptyFunction() {
// Functions with this map will not have a 'prototype' property, and
// can not be used as constructors.
fm = Factory::NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
global_context()->set_function_without_prototype_map(*fm);
function_map_descriptors =
Handle<Map> function_without_prototype_map =
Factory::NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
global_context()->set_function_without_prototype_map(
*function_without_prototype_map);
Handle<DescriptorArray> function_without_prototype_map_descriptors =
ComputeFunctionInstanceDescriptor(DONT_ADD_PROTOTYPE);
fm->set_instance_descriptors(*function_map_descriptors);
fm->set_function_with_prototype(false);
function_without_prototype_map->set_instance_descriptors(
*function_without_prototype_map_descriptors);
function_without_prototype_map->set_function_with_prototype(false);
// Allocate the function map first and then patch the prototype later
fm = Factory::NewMap(JS_FUNCTION_TYPE, JSFunction::kSize);
@ -459,7 +462,7 @@ Handle<JSFunction> Genesis::CreateEmptyFunction() {
// 262 15.3.4.
Handle<String> symbol = Factory::LookupAsciiSymbol("Empty");
Handle<JSFunction> empty_function =
Factory::NewFunction(symbol, Factory::null_value());
Factory::NewFunctionWithoutPrototype(symbol);
// --- E m p t y ---
Handle<Code> code =
@ -474,15 +477,14 @@ Handle<JSFunction> Genesis::CreateEmptyFunction() {
empty_function->shared()->DontAdaptArguments();
global_context()->function_map()->set_prototype(*empty_function);
global_context()->function_instance_map()->set_prototype(*empty_function);
// Allocate a distinct prototype for the function map for functions without
// prototype, so it will not add 'prototype' property in the proto chain.
global_context()->function_without_prototype_map()->set_prototype(
*Factory::NewJSObject(Top::object_function(), TENURED));
global_context()->function_without_prototype_map()->
set_prototype(*empty_function);
// Allocate the function map first and then patch the prototype later
Handle<Map> empty_fm = Factory::CopyMapDropDescriptors(fm);
empty_fm->set_instance_descriptors(*function_map_descriptors);
Handle<Map> empty_fm = Factory::CopyMapDropDescriptors(
function_without_prototype_map);
empty_fm->set_instance_descriptors(
*function_without_prototype_map_descriptors);
empty_fm->set_prototype(global_context()->object_function()->prototype());
empty_function->set_map(*empty_fm);
return empty_function;
@ -1258,23 +1260,6 @@ bool Genesis::InstallNatives() {
// Set the lengths for the functions to satisfy ECMA-262.
call->shared()->set_length(1);
apply->shared()->set_length(2);
// Install the call, apply, toString and constructor properties
// for the functions without prototype.
Handle<JSObject> wp_proto = Handle<JSObject>(
JSObject::cast(Top::function_without_prototype_map()->prototype()));
Handle<String> call_symbol = Factory::LookupAsciiSymbol("call");
SetProperty(wp_proto, call_symbol, call, DONT_ENUM);
Handle<String> apply_symbol = Factory::LookupAsciiSymbol("apply");
SetProperty(wp_proto, apply_symbol, apply, DONT_ENUM);
Handle<Object> to_string = GetProperty(proto, "toString");
Handle<String> to_string_symbol = Factory::LookupAsciiSymbol("toString");
SetProperty(wp_proto, to_string_symbol, to_string, DONT_ENUM);
SetProperty(wp_proto, Factory::constructor_symbol(), function, DONT_ENUM);
}
// Create a constructor for RegExp results (a variant of Array that

5
test/mjsunit/unusual-constructor.js
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@ -25,12 +25,9 @@
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
var obj = new (Function.__proto__)();
var threw = false;
try {
obj.toString();
var obj = new (Function.__proto__)();
} catch (e) {
assertInstanceof(e, TypeError);
threw = true;