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Make setting of accessors even more atomic.

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Now the whole getter/setter/attributes triple gets created/set together,
avoiding any hacks regarding previous values/attributes, making things a lot
simpler.

While doing this, an interesting problem surfaced, which has been there for a
long time: After adding/changing acessors in slow mode, we could potentially
fail going back to fast mode because of a failed memory allocation, signaling
the need for a GC. But we have already changed the object in slow mode, so we
are not idempotent and the retry would trigger a newly inserted assertion
(namely, that the code obeys access restrictions). This has been solved by
splitting the transformation to fast mode from the actual setting of the
accessors.

Review URL: https://chromiumcodereview.appspot.com/9716035

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11112 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
svenpanne@chromium.org 2012-03-23 09:51:56 +00:00
parent b7dca5d5a7
commit 4cb600962f
4 changed files with 68 additions and 86 deletions
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5
src/api.cc
View File

@ -3064,8 +3064,11 @@ bool Object::SetAccessor(Handle<String> name,
i::Handle<i::AccessorInfo> info = MakeAccessorInfo(name,
getter, setter, data,
settings, attributes);
bool fast = Utils::OpenHandle(this)->HasFastProperties();
i::Handle<i::Object> result = i::SetAccessor(Utils::OpenHandle(this), info);
return !result.is_null() && !result->IsUndefined();
if (result.is_null() || result->IsUndefined()) return false;
if (fast) i::JSObject::TransformToFastProperties(Utils::OpenHandle(this), 0);
return true;
}

77
src/objects.cc
View File

@ -4324,21 +4324,20 @@ void JSObject::LookupCallback(String* name, LookupResult* result) {
static bool UpdateGetterSetterInDictionary(
SeededNumberDictionary* dictionary,
uint32_t index,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes) {
int entry = dictionary->FindEntry(index);
if (entry != SeededNumberDictionary::kNotFound) {
Object* result = dictionary->ValueAt(entry);
PropertyDetails details = dictionary->DetailsAt(entry);
// TODO(mstarzinger): We should check for details.IsDontDelete() here once
// we only call into the runtime once to set both getter and setter.
if (details.type() == CALLBACKS && result->IsAccessorPair()) {
ASSERT(!details.IsDontDelete());
if (details.attributes() != attributes) {
dictionary->DetailsAtPut(entry,
PropertyDetails(attributes, CALLBACKS, index));
}
AccessorPair::cast(result)->set(component, fun);
AccessorPair::cast(result)->SetComponents(getter, setter);
return true;
}
}
@ -4347,8 +4346,8 @@ static bool UpdateGetterSetterInDictionary(
MaybeObject* JSObject::DefineElementAccessor(uint32_t index,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes) {
switch (GetElementsKind()) {
case FAST_SMI_ONLY_ELEMENTS:
@ -4369,8 +4368,8 @@ MaybeObject* JSObject::DefineElementAccessor(uint32_t index,
case DICTIONARY_ELEMENTS:
if (UpdateGetterSetterInDictionary(element_dictionary(),
index,
component,
fun,
getter,
setter,
attributes)) {
return GetHeap()->undefined_value();
}
@ -4390,8 +4389,8 @@ MaybeObject* JSObject::DefineElementAccessor(uint32_t index,
SeededNumberDictionary::cast(arguments);
if (UpdateGetterSetterInDictionary(dictionary,
index,
component,
fun,
getter,
setter,
attributes)) {
return GetHeap()->undefined_value();
}
@ -4405,23 +4404,22 @@ MaybeObject* JSObject::DefineElementAccessor(uint32_t index,
{ MaybeObject* maybe_accessors = GetHeap()->AllocateAccessorPair();
if (!maybe_accessors->To(&accessors)) return maybe_accessors;
}
accessors->set(component, fun);
accessors->SetComponents(getter, setter);
return SetElementCallback(index, accessors, attributes);
}
MaybeObject* JSObject::DefinePropertyAccessor(String* name,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes) {
// Lookup the name.
LookupResult result(GetHeap()->isolate());
LocalLookupRealNamedProperty(name, &result);
if (result.IsFound()) {
// TODO(mstarzinger): We should check for result.IsDontDelete() here once
// we only call into the runtime once to set both getter and setter.
if (result.type() == CALLBACKS) {
ASSERT(!result.IsDontDelete());
Object* obj = result.GetCallbackObject();
// Need to preserve old getters/setters.
if (obj->IsAccessorPair()) {
@ -4430,7 +4428,7 @@ MaybeObject* JSObject::DefinePropertyAccessor(String* name,
AccessorPair::cast(obj)->CopyWithoutTransitions();
if (!maybe_copy->To(&copy)) return maybe_copy;
}
copy->set(component, fun);
copy->SetComponents(getter, setter);
// Use set to update attributes.
return SetPropertyCallback(name, copy, attributes);
}
@ -4441,7 +4439,7 @@ MaybeObject* JSObject::DefinePropertyAccessor(String* name,
{ MaybeObject* maybe_accessors = GetHeap()->AllocateAccessorPair();
if (!maybe_accessors->To(&accessors)) return maybe_accessors;
}
accessors->set(component, fun);
accessors->SetComponents(getter, setter);
return SetPropertyCallback(name, accessors, attributes);
}
@ -4512,12 +4510,6 @@ MaybeObject* JSObject::SetElementCallback(uint32_t index,
MaybeObject* JSObject::SetPropertyCallback(String* name,
Object* structure,
PropertyAttributes attributes) {
PropertyDetails details = PropertyDetails(attributes, CALLBACKS);
bool convert_back_to_fast = HasFastProperties() &&
(map()->instance_descriptors()->number_of_descriptors()
< DescriptorArray::kMaxNumberOfDescriptors);
// Normalize object to make this operation simple.
{ MaybeObject* maybe_ok = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
if (maybe_ok->IsFailure()) return maybe_ok;
@ -4538,22 +4530,29 @@ MaybeObject* JSObject::SetPropertyCallback(String* name,
}
// Update the dictionary with the new CALLBACKS property.
PropertyDetails details = PropertyDetails(attributes, CALLBACKS);
{ MaybeObject* maybe_ok = SetNormalizedProperty(name, structure, details);
if (maybe_ok->IsFailure()) return maybe_ok;
}
if (convert_back_to_fast) {
MaybeObject* maybe_ok = TransformToFastProperties(0);
if (maybe_ok->IsFailure()) return maybe_ok;
}
return GetHeap()->undefined_value();
}
void JSObject::DefineAccessor(Handle<JSObject> object,
Handle<String> name,
Handle<Object> getter,
Handle<Object> setter,
PropertyAttributes attributes) {
CALL_HEAP_FUNCTION_VOID(
object->GetIsolate(),
object->DefineAccessor(*name, *getter, *setter, attributes));
}
MaybeObject* JSObject::DefineAccessor(String* name,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes) {
ASSERT(fun->IsSpecFunction() || fun->IsUndefined());
Isolate* isolate = GetIsolate();
// Check access rights if needed.
if (IsAccessCheckNeeded() &&
@ -4566,8 +4565,8 @@ MaybeObject* JSObject::DefineAccessor(String* name,
Object* proto = GetPrototype();
if (proto->IsNull()) return this;
ASSERT(proto->IsJSGlobalObject());
return JSObject::cast(proto)->DefineAccessor(name, component,
fun, attributes);
return JSObject::cast(proto)->DefineAccessor(
name, getter, setter, attributes);
}
// Make sure that the top context does not change when doing callbacks or
@ -4581,8 +4580,8 @@ MaybeObject* JSObject::DefineAccessor(String* name,
uint32_t index = 0;
return name->AsArrayIndex(&index) ?
DefineElementAccessor(index, component, fun, attributes) :
DefinePropertyAccessor(name, component, fun, attributes);
DefineElementAccessor(index, getter, setter, attributes) :
DefinePropertyAccessor(name, getter, setter, attributes);
}
@ -4696,7 +4695,7 @@ Object* JSObject::LookupAccessor(String* name, AccessorComponent component) {
Object* element = dictionary->ValueAt(entry);
if (dictionary->DetailsAt(entry).type() == CALLBACKS &&
element->IsAccessorPair()) {
return AccessorPair::cast(element)->SafeGet(component);
return AccessorPair::cast(element)->GetComponent(component);
}
}
}
@ -4712,7 +4711,7 @@ Object* JSObject::LookupAccessor(String* name, AccessorComponent component) {
if (result.type() == CALLBACKS) {
Object* obj = result.GetCallbackObject();
if (obj->IsAccessorPair()) {
return AccessorPair::cast(obj)->SafeGet(component);
return AccessorPair::cast(obj)->GetComponent(component);
}
}
}
@ -5949,8 +5948,8 @@ MaybeObject* AccessorPair::CopyWithoutTransitions() {
}
Object* AccessorPair::SafeGet(AccessorComponent component) {
Object* accessor = get(component);
Object* AccessorPair::GetComponent(AccessorComponent component) {
Object* accessor = (component == ACCESSOR_GETTER) ? getter() : setter();
return accessor->IsTheHole() ? GetHeap()->undefined_value() : accessor;
}

37
src/objects.h
View File

@ -1627,9 +1627,14 @@ class JSObject: public JSReceiver {
String* name,
bool continue_search);
static void DefineAccessor(Handle<JSObject> object,
Handle<String> name,
Handle<Object> getter,
Handle<Object> setter,
PropertyAttributes attributes);
MUST_USE_RESULT MaybeObject* DefineAccessor(String* name,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes);
Object* LookupAccessor(String* name, AccessorComponent component);
@ -2178,13 +2183,13 @@ class JSObject: public JSReceiver {
PropertyAttributes attributes);
MUST_USE_RESULT MaybeObject* DefineElementAccessor(
uint32_t index,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes);
MUST_USE_RESULT MaybeObject* DefinePropertyAccessor(
String* name,
AccessorComponent component,
Object* fun,
Object* getter,
Object* setter,
PropertyAttributes attributes);
void LookupInDescriptor(String* name, LookupResult* result);
@ -8045,23 +8050,15 @@ class AccessorPair: public Struct {
MUST_USE_RESULT MaybeObject* CopyWithoutTransitions();
Object* get(AccessorComponent component) {
ASSERT(component == ACCESSOR_GETTER || component == ACCESSOR_SETTER);
return (component == ACCESSOR_GETTER) ? getter() : setter();
}
// Note: Returns undefined instead in case of a hole.
Object* GetComponent(AccessorComponent component);
void set(AccessorComponent component, Object* value) {
ASSERT(component == ACCESSOR_GETTER || component == ACCESSOR_SETTER);
if (component == ACCESSOR_GETTER) {
set_getter(value);
} else {
set_setter(value);
}
// Set both components, skipping arguments which are a JavaScript null.
void SetComponents(Object* getter, Object* setter) {
if (!getter->IsNull()) set_getter(getter);
if (!setter->IsNull()) set_setter(setter);
}
// Same as get, but returns undefined instead of the hole.
Object* SafeGet(AccessorComponent component);
bool ContainsAccessor() {
return IsJSAccessor(getter()) || IsJSAccessor(setter());
}

35
src/runtime.cc
View File

@ -1065,10 +1065,10 @@ static MaybeObject* GetOwnProperty(Isolate* isolate,
AccessorPair::cast(dictionary->ValueAt(entry));
elms->set(IS_ACCESSOR_INDEX, heap->true_value());
if (CheckElementAccess(*obj, index, v8::ACCESS_GET)) {
elms->set(GETTER_INDEX, accessors->SafeGet(ACCESSOR_GETTER));
elms->set(GETTER_INDEX, accessors->GetComponent(ACCESSOR_GETTER));
}
if (CheckElementAccess(*obj, index, v8::ACCESS_SET)) {
elms->set(SETTER_INDEX, accessors->SafeGet(ACCESSOR_SETTER));
elms->set(SETTER_INDEX, accessors->GetComponent(ACCESSOR_SETTER));
}
break;
}
@ -1115,10 +1115,10 @@ static MaybeObject* GetOwnProperty(Isolate* isolate,
AccessorPair* accessors = AccessorPair::cast(result.GetCallbackObject());
if (CheckAccess(*obj, *name, &result, v8::ACCESS_GET)) {
elms->set(GETTER_INDEX, accessors->SafeGet(ACCESSOR_GETTER));
elms->set(GETTER_INDEX, accessors->GetComponent(ACCESSOR_GETTER));
}
if (CheckAccess(*obj, *name, &result, v8::ACCESS_SET)) {
elms->set(SETTER_INDEX, accessors->SafeGet(ACCESSOR_SETTER));
elms->set(SETTER_INDEX, accessors->GetComponent(ACCESSOR_SETTER));
}
} else {
elms->set(IS_ACCESSOR_INDEX, heap->false_value());
@ -4350,26 +4350,9 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DefineOrRedefineAccessorProperty) {
RUNTIME_ASSERT((unchecked & ~(READ_ONLY | DONT_ENUM | DONT_DELETE)) == 0);
PropertyAttributes attr = static_cast<PropertyAttributes>(unchecked);
// TODO(svenpanne) Define getter/setter/attributes in a single step.
if (getter->IsNull() && setter->IsNull()) {
JSArray* array;
{ MaybeObject* maybe_array = GetOwnProperty(isolate, obj, name);
if (!maybe_array->To(&array)) return maybe_array;
}
Object* current = FixedArray::cast(array->elements())->get(GETTER_INDEX);
getter = Handle<Object>(current, isolate);
}
if (!getter->IsNull()) {
MaybeObject* ok =
obj->DefineAccessor(*name, ACCESSOR_GETTER, *getter, attr);
if (ok->IsFailure()) return ok;
}
if (!setter->IsNull()) {
MaybeObject* ok =
obj->DefineAccessor(*name, ACCESSOR_SETTER, *setter, attr);
if (ok->IsFailure()) return ok;
}
bool fast = obj->HasFastProperties();
JSObject::DefineAccessor(obj, name, getter, setter, attr);
if (fast) JSObject::TransformToFastProperties(obj, 0);
return isolate->heap()->undefined_value();
}
@ -10231,8 +10214,8 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugGetPropertyDetails) {
if (hasJavaScriptAccessors) {
AccessorPair* accessors = AccessorPair::cast(*result_callback_obj);
details->set(2, isolate->heap()->ToBoolean(caught_exception));
details->set(3, accessors->SafeGet(ACCESSOR_GETTER));
details->set(4, accessors->SafeGet(ACCESSOR_SETTER));
details->set(3, accessors->GetComponent(ACCESSOR_GETTER));
details->set(4, accessors->GetComponent(ACCESSOR_SETTER));
}
return *isolate->factory()->NewJSArrayWithElements(details);