Convert most remaining return values from Value to ReturnedValue

Change-Id: If8b0c3b91be50678693868c10fefc3678008834d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

59 files changed, 553 insertions, 498 deletions

diff --git a/src/imports/localstorage/plugin.cpp b/src/imports/localstorage/plugin.cpp
index 83d73c5bc9..14c49a08e1 100644
--- a/src/imports/localstorage/plugin.cpp
+++ b/src/imports/localstorage/plugin.cpp
@@ -204,7 +204,7 @@ static ReturnedValue qmlsqldatabase_rows_index(QQmlSqlDatabaseWrapper *r, Execut
             if (v.isNull()) {
                 row->put(v4->newIdentifier(record.fieldName(ii)), Value::nullValue());
             } else {
-                row->put(v4->newIdentifier(record.fieldName(ii)), v8->fromVariant(v));
+                row->put(v4->newIdentifier(record.fieldName(ii)), Value::fromReturnedValue(v8->fromVariant(v)));
             }
         }
         if (hasProperty)
@@ -257,7 +257,8 @@ static ReturnedValue qmlsqldatabase_executeSql(SimpleCallContext *ctx)
     QSqlQuery query(db);
     bool err = false;
 
-    Value result = Value::undefinedValue();
+    Scope scope(QV8Engine::getV4(engine));
+    ScopedValue result(scope, Value::undefinedValue());
 
     if (query.prepare(sql)) {
         if (ctx->argumentCount > 1) {
@@ -268,17 +269,18 @@ static ReturnedValue qmlsqldatabase_executeSql(SimpleCallContext *ctx)
                     query.bindValue(ii, engine->toVariant(QV4::Value::fromReturnedValue(array->getIndexed(ii)), -1));
             } else if (Object *object = values.asObject()) {
                 ObjectIterator it(object, ObjectIterator::WithProtoChain|ObjectIterator::EnumerableOnly);
+                ScopedValue key(scope);
                 while (1) {
                     Value value;
-                    Value key = it.nextPropertyName(&value);
-                    if (key.isNull())
+                    key = it.nextPropertyName(&value);
+                    if (key->isNull())
                         break;
                     QVariant v = engine->toVariant(value, -1);
-                    if (key.isString()) {
-                        query.bindValue(key.stringValue()->toQString(), v);
+                    if (key->isString()) {
+                        query.bindValue(key->stringValue()->toQString(), v);
                     } else {
-                        assert(key.isInteger());
-                        query.bindValue(key.integerValue(), v);
+                        assert(key->isInteger());
+                        query.bindValue(key->integerValue(), v);
                     }
                 }
             } else {
diff --git a/src/imports/xmllistmodel/qqmlxmllistmodel.cpp b/src/imports/xmllistmodel/qqmlxmllistmodel.cpp
index c12bfee924..9f6437625d 100644
--- a/src/imports/xmllistmodel/qqmlxmllistmodel.cpp
+++ b/src/imports/xmllistmodel/qqmlxmllistmodel.cpp
@@ -926,7 +926,7 @@ QQmlV4Handle QQuickXmlListModel::get(int index) const
     Object *o = v4engine->newObject();
     for (int ii = 0; ii < d->roleObjects.count(); ++ii) {
         Property *p = o->insertMember(v4engine->newIdentifier(d->roleObjects[ii]->name()), PropertyAttributes());
-        p->value = v8engine->fromVariant(d->data.value(ii).value(index));
+        p->value = Value::fromReturnedValue(v8engine->fromVariant(d->data.value(ii).value(index)));
     }
 
     return QQmlV4Handle(Value::fromObject(o));
diff --git a/src/qml/jsapi/qjsengine.cpp b/src/qml/jsapi/qjsengine.cpp
index 7bc8b80396..0f291d7c98 100644
--- a/src/qml/jsapi/qjsengine.cpp
+++ b/src/qml/jsapi/qjsengine.cpp
@@ -327,8 +327,10 @@ QJSValue QJSEngine::newQObject(QObject *object)
 {
     Q_D(QJSEngine);
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(d);
+    QV4::Scope scope(v4);
     QQmlEngine::setObjectOwnership(object, QQmlEngine::JavaScriptOwnership);
-    return new QJSValuePrivate(v4, QV4::QObjectWrapper::wrap(v4, object));
+    QV4::ScopedValue v(scope, QV4::QObjectWrapper::wrap(v4, object));
+    return new QJSValuePrivate(v4, v);
 }
 
 /*!
@@ -353,7 +355,7 @@ QJSValue QJSEngine::globalObject() const
 QJSValue QJSEngine::create(int type, const void *ptr)
 {
     Q_D(QJSEngine);
-    return new QJSValuePrivate(d->m_v4Engine, d->metaTypeToJS(type, ptr));
+    return new QJSValuePrivate(d->m_v4Engine, QV4::Value::fromReturnedValue(d->metaTypeToJS(type, ptr)));
 }
 
 /*!
@@ -365,7 +367,7 @@ bool QJSEngine::convertV2(const QJSValue &value, int type, void *ptr)
     QJSValuePrivate *vp = QJSValuePrivate::get(value);
     QV8Engine *engine = vp->engine ? vp->engine->v8Engine : 0;
     if (engine) {
-        return engine->metaTypeFromJS(vp->getValue(engine->m_v4Engine), type, ptr);
+        return engine->metaTypeFromJS(QV4::Value::fromReturnedValue(vp->getValue(engine->m_v4Engine)), type, ptr);
     } else {
         switch (type) {
             case QMetaType::Bool:
diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index e596cb6303..ca2f398f2f 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -57,13 +57,13 @@
 #include <private/qv4exception_p.h>
 #include <private/qv4scopedvalue_p.h>
 
-QV4::Value QJSValuePrivate::getValue(QV4::ExecutionEngine *e)
+QV4::ReturnedValue QJSValuePrivate::getValue(QV4::ExecutionEngine *e)
 {
     if (!this->engine)
         this->engine = e;
     else if (this->engine != e) {
         qWarning("JSValue can't be reassigned to another engine.");
-        return QV4::Value::emptyValue();
+        return QV4::Value::emptyValue().asReturnedValue();
     }
     if (value.asString() == &string) {
         value = QV4::Value::fromString(engine->newString(string.toQString()));
@@ -74,7 +74,7 @@ QV4::Value QJSValuePrivate::getValue(QV4::ExecutionEngine *e)
         if (next)
             next->prev = &this->next;
     }
-    return value;
+    return value.asReturnedValue();
 }
 
 /*!
@@ -514,7 +514,7 @@ QJSValue QJSValue::call(const QJSValueList &args)
             qWarning("QJSValue::call() failed: cannot call function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = args.at(i).d->getValue(engine);
+        callData->args[i] = QV4::Value::fromReturnedValue(args.at(i).d->getValue(engine));
     }
 
     ScopedValue result(scope);
@@ -565,13 +565,13 @@ QJSValue QJSValue::callWithInstance(const QJSValue &instance, const QJSValueList
     }
 
     ScopedCallData callData(scope, args.size());
-    callData->thisObject = instance.d->getValue(engine);
+    callData->thisObject = QV4::Value::fromReturnedValue(instance.d->getValue(engine));
     for (int i = 0; i < args.size(); ++i) {
         if (!args.at(i).d->checkEngine(engine)) {
             qWarning("QJSValue::call() failed: cannot call function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = args.at(i).d->getValue(engine);
+        callData->args[i] = QV4::Value::fromReturnedValue(args.at(i).d->getValue(engine));
     }
 
     ScopedValue result(scope);
@@ -620,7 +620,7 @@ QJSValue QJSValue::callAsConstructor(const QJSValueList &args)
             qWarning("QJSValue::callAsConstructor() failed: cannot construct function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = args.at(i).d->getValue(engine);
+        callData->args[i] = QV4::Value::fromReturnedValue(args.at(i).d->getValue(engine));
     }
 
     ScopedValue result(scope);
@@ -864,7 +864,12 @@ QJSValue QJSValue::property(quint32 arrayIndex) const
 */
 void QJSValue::setProperty(const QString& name, const QJSValue& value)
 {
-    Object *o = d->value.asObject();
+    ExecutionEngine *engine = d->engine;
+    if (!engine)
+        return;
+    Scope scope(engine);
+
+    Scoped<Object> o(scope, d->value);
     if (!o)
         return;
 
@@ -873,7 +878,6 @@ void QJSValue::setProperty(const QString& name, const QJSValue& value)
         return;
     }
 
-    ExecutionEngine *engine = d->engine;
     String *s = engine->newString(name);
     uint idx = s->asArrayIndex();
     if (idx < UINT_MAX) {
@@ -884,7 +888,8 @@ void QJSValue::setProperty(const QString& name, const QJSValue& value)
     QV4::ExecutionContext *ctx = engine->current;
     s->makeIdentifier();
     try {
-        o->put(s, value.d->getValue(engine));
+        QV4::ScopedValue v(scope, value.d->getValue(engine));
+        o->put(s, v);
     } catch (QV4::Exception &e) {
         e.accept(ctx);
     }
@@ -904,17 +909,22 @@ void QJSValue::setProperty(const QString& name, const QJSValue& value)
 */
 void QJSValue::setProperty(quint32 arrayIndex, const QJSValue& value)
 {
-    Object *o = d->value.asObject();
+    ExecutionEngine *engine = d->engine;
+    if (!engine)
+        return;
+    Scope scope(engine);
+
+    Scoped<Object> o(scope, d->value);
     if (!o)
         return;
 
-    ExecutionEngine *engine = d->engine;
     QV4::ExecutionContext *ctx = engine->current;
+    QV4::ScopedValue v(scope, value.d->getValue(engine));
     try {
         if (arrayIndex != UINT_MAX)
-            o->putIndexed(arrayIndex, value.d->getValue(engine));
+            o->putIndexed(arrayIndex, v);
         else
-            o->put(engine->id_uintMax, value.d->getValue(engine));
+            o->put(engine->id_uintMax, v);
     } catch (QV4::Exception &e) {
         e.accept(ctx);
     }
diff --git a/src/qml/jsapi/qjsvalue_p.h b/src/qml/jsapi/qjsvalue_p.h
index 69046e84df..f99fed7c44 100644
--- a/src/qml/jsapi/qjsvalue_p.h
+++ b/src/qml/jsapi/qjsvalue_p.h
@@ -88,7 +88,7 @@ public:
         value = QV4::Value::fromString(&string);
     }
 
-    QV4::Value getValue(QV4::ExecutionEngine *e);
+    QV4::ReturnedValue getValue(QV4::ExecutionEngine *e);
 
     static QJSValuePrivate *get(const QJSValue &v) { return v.d; }
 
diff --git a/src/qml/jsruntime/qv4arrayobject.cpp b/src/qml/jsruntime/qv4arrayobject.cpp
index 10d8f4e5c1..5508372265 100644
--- a/src/qml/jsruntime/qv4arrayobject.cpp
+++ b/src/qml/jsruntime/qv4arrayobject.cpp
@@ -600,7 +600,7 @@ ReturnedValue ArrayPrototype::method_indexOf(SimpleCallContext *ctx)
         return Value::fromInt32(-1).asReturnedValue();
     }
 
-    return instance->arrayIndexOf(searchValue, fromIndex, len, ctx, instance).asReturnedValue();
+    return instance->arrayIndexOf(searchValue, fromIndex, len, ctx, instance);
 }
 
 ReturnedValue ArrayPrototype::method_lastIndexOf(SimpleCallContext *ctx)
diff --git a/src/qml/jsruntime/qv4debugging.cpp b/src/qml/jsruntime/qv4debugging.cpp
index 8080ed6c62..2b6dc4616c 100644
--- a/src/qml/jsruntime/qv4debugging.cpp
+++ b/src/qml/jsruntime/qv4debugging.cpp
@@ -209,6 +209,9 @@ static void realDumpValue(QV4::Value v, QV4::ExecutionContext *ctx, std::string
 {
     using namespace QV4;
     using namespace std;
+
+    Scope scope(ctx);
+
     cout << prefix << "tag: " << hex << v.tag << dec << endl << prefix << "\t-> ";
     switch (v.type()) {
     case Value::Undefined_Type: cout << "Undefined" << endl; return;
@@ -271,10 +274,11 @@ static void realDumpValue(QV4::Value v, QV4::ExecutionContext *ctx, std::string
 
     cout << prefix << "properties:" << endl;
     ForEachIteratorObject it(ctx, o);
-    for (Value name = it.nextPropertyName(); !name.isNull(); name = it.nextPropertyName()) {
-        cout << prefix << "\t\"" << qPrintable(name.stringValue()->toQString()) << "\"" << endl;
+    QV4::ScopedValue name(scope);
+    for (name = it.nextPropertyName(); !name->isNull(); name = it.nextPropertyName()) {
+        cout << prefix << "\t\"" << qPrintable(name->stringValue()->toQString()) << "\"" << endl;
         PropertyAttributes attrs;
-        Property *d = o->__getOwnProperty__(name.stringValue(), &attrs);
+        Property *d = o->__getOwnProperty__(name->stringValue(), &attrs);
         Value pval = Value::fromReturnedValue(o->getValue(d, attrs));
         cout << prefix << "\tvalue:" << endl;
         realDumpValue(pval, ctx, prefix + "\t");
diff --git a/src/qml/jsruntime/qv4functionobject.cpp b/src/qml/jsruntime/qv4functionobject.cpp
index a80ea3fc12..a13aa2c29d 100644
--- a/src/qml/jsruntime/qv4functionobject.cpp
+++ b/src/qml/jsruntime/qv4functionobject.cpp
@@ -618,6 +618,7 @@ ReturnedValue IndexedBuiltinFunction::call(Managed *that, CallData *callData)
     IndexedBuiltinFunction *f = static_cast<IndexedBuiltinFunction *>(that);
     ExecutionEngine *v4 = f->engine();
     ExecutionContext *context = v4->current;
+    Scope scope(v4);
 
     SimpleCallContext ctx;
     ctx.initSimpleCallContext(f->scope->engine);
@@ -628,7 +629,7 @@ ReturnedValue IndexedBuiltinFunction::call(Managed *that, CallData *callData)
     ctx.argumentCount = callData->argc;
     v4->pushContext(&ctx);
 
-    Value result;
+    ScopedValue result(scope);
     try {
         result = f->code(&ctx, f->index);
     } catch (Exception &ex) {
diff --git a/src/qml/jsruntime/qv4functionobject_p.h b/src/qml/jsruntime/qv4functionobject_p.h
index 25bc39047f..37f9d0bf46 100644
--- a/src/qml/jsruntime/qv4functionobject_p.h
+++ b/src/qml/jsruntime/qv4functionobject_p.h
@@ -180,10 +180,10 @@ struct IndexedBuiltinFunction: FunctionObject
 {
     Q_MANAGED
 
-    Value (*code)(SimpleCallContext *ctx, uint index);
+    ReturnedValue (*code)(SimpleCallContext *ctx, uint index);
     uint index;
 
-    IndexedBuiltinFunction(ExecutionContext *scope, uint index, Value (*code)(SimpleCallContext *ctx, uint index))
+    IndexedBuiltinFunction(ExecutionContext *scope, uint index, ReturnedValue (*code)(SimpleCallContext *ctx, uint index))
         : FunctionObject(scope, /*name*/0)
         , code(code)
         , index(index)
diff --git a/src/qml/jsruntime/qv4include.cpp b/src/qml/jsruntime/qv4include.cpp
index 43e566b5fb..ac9a50c3a1 100644
--- a/src/qml/jsruntime/qv4include.cpp
+++ b/src/qml/jsruntime/qv4include.cpp
@@ -82,7 +82,7 @@ QV4Include::~QV4Include()
     delete m_reply; m_reply = 0;
 }
 
-QV4::Value QV4Include::resultValue(QV4::ExecutionEngine *v4, Status status)
+QV4::ReturnedValue QV4Include::resultValue(QV4::ExecutionEngine *v4, Status status)
 {
 
     // XXX It seems inefficient to create this object from scratch each time.
@@ -94,7 +94,7 @@ QV4::Value QV4Include::resultValue(QV4::ExecutionEngine *v4, Status status)
 
     o->put(v4->newString("status"), QV4::Value::fromInt32(status));
 
-    return QV4::Value::fromObject(o);
+    return QV4::Value::fromObject(o).asReturnedValue();
 }
 
 void QV4Include::callback(const QV4::Value &callback, const QV4::Value &status)
@@ -115,9 +115,9 @@ void QV4Include::callback(const QV4::Value &callback, const QV4::Value &status)
     }
 }
 
-QV4::Value QV4Include::result()
+QV4::ReturnedValue QV4Include::result()
 {
-    return m_resultObject.value();
+    return m_resultObject.value().asReturnedValue();
 }
 
 #define INCLUDE_MAXIMUM_REDIRECT_RECURSION 15
diff --git a/src/qml/jsruntime/qv4include_p.h b/src/qml/jsruntime/qv4include_p.h
index ccc634e066..6e299bce91 100644
--- a/src/qml/jsruntime/qv4include_p.h
+++ b/src/qml/jsruntime/qv4include_p.h
@@ -88,9 +88,9 @@ private:
                const QV4::Value &qmlglobal, const QV4::Value &callback);
     ~QV4Include();
 
-    QV4::Value result();
+    QV4::ReturnedValue result();
 
-    static QV4::Value resultValue(QV4::ExecutionEngine *v4, Status status = Loading);
+    static QV4::ReturnedValue resultValue(QV4::ExecutionEngine *v4, Status status = Loading);
     static void callback(const QV4::Value &callback, const QV4::Value &status);
 
     QV4::ExecutionEngine *v4;
diff --git a/src/qml/jsruntime/qv4jsonobject.cpp b/src/qml/jsruntime/qv4jsonobject.cpp
index f63d67ef0e..a42cfd4873 100644
--- a/src/qml/jsruntime/qv4jsonobject.cpp
+++ b/src/qml/jsruntime/qv4jsonobject.cpp
@@ -783,13 +783,14 @@ QString Stringify::JO(Object *o)
     QStringList partial;
     if (propertyList.isEmpty()) {
         ObjectIterator it(o, ObjectIterator::EnumerableOnly);
+        ScopedValue name(scope);
 
         while (1) {
             Value v;
-            Value name = it.nextPropertyNameAsString(&v);
-            if (name.isNull())
+            name = it.nextPropertyNameAsString(&v);
+            if (name->isNull())
                 break;
-            QString key = name.toQStringNoThrow();
+            QString key = name->toQStringNoThrow();
             QString member = makeMember(key, v);
             if (!member.isEmpty())
                 partial += member;
@@ -936,22 +937,22 @@ ReturnedValue JsonObject::method_stringify(SimpleCallContext *ctx)
 
 
 
-QV4::Value JsonObject::fromJsonValue(ExecutionEngine *engine, const QJsonValue &value)
+ReturnedValue JsonObject::fromJsonValue(ExecutionEngine *engine, const QJsonValue &value)
 {
     if (value.isString())
-        return Value::fromString(engine->current, value.toString());
+        return Value::fromString(engine->current, value.toString()).asReturnedValue();
     else if (value.isDouble())
-        return Value::fromDouble(value.toDouble());
+        return Encode(value.toDouble());
     else if (value.isBool())
-        return Value::fromBoolean(value.toBool());
+        return Encode(value.toBool());
     else if (value.isArray())
         return fromJsonArray(engine, value.toArray());
     else if (value.isObject())
         return fromJsonObject(engine, value.toObject());
     else if (value.isNull())
-        return Value::nullValue();
+        return Encode::null();
     else
-        return Value::undefinedValue();
+        return Encode::undefined();
 }
 
 QJsonValue JsonObject::toJsonValue(const QV4::Value &value,
@@ -973,12 +974,13 @@ QJsonValue JsonObject::toJsonValue(const QV4::Value &value,
         return QJsonValue(QJsonValue::Undefined);
 }
 
-QV4::Value JsonObject::fromJsonObject(ExecutionEngine *engine, const QJsonObject &object)
+QV4::ReturnedValue JsonObject::fromJsonObject(ExecutionEngine *engine, const QJsonObject &object)
 {
-    Object *o = engine->newObject();
+    Scope scope(engine);
+    Scoped<Object> o(scope, Value::fromObject(engine->newObject()));
     for (QJsonObject::const_iterator it = object.begin(); it != object.end(); ++it)
-        o->put(engine->newString(it.key()), fromJsonValue(engine, it.value()));
-    return Value::fromObject(o);
+        o->put(engine->newString(it.key()), Value::fromReturnedValue(fromJsonValue(engine, it.value())));
+    return o.asReturnedValue();
 }
 
 QJsonObject JsonObject::toJsonObject(QV4::Object *o, V4ObjectSet &visitedObjects)
@@ -987,6 +989,8 @@ QJsonObject JsonObject::toJsonObject(QV4::Object *o, V4ObjectSet &visitedObjects
     if (!o || o->asFunctionObject())
         return result;
 
+    Scope scope(o->engine());
+
     if (visitedObjects.contains(o)) {
         // Avoid recursion.
         // For compatibility with QVariant{List,Map} conversion, we return an
@@ -997,13 +1001,14 @@ QJsonObject JsonObject::toJsonObject(QV4::Object *o, V4ObjectSet &visitedObjects
     visitedObjects.insert(o);
 
     ObjectIterator it(o, ObjectIterator::EnumerableOnly);
+    ScopedValue name(scope);
     while (1) {
         Value v;
-        Value name = it.nextPropertyNameAsString(&v);
-        if (name.isNull())
+        name = it.nextPropertyNameAsString(&v);
+        if (name->isNull())
             break;
 
-        QString key = name.toQStringNoThrow();
+        QString key = name->toQStringNoThrow();
         if (!v.asFunctionObject())
             result.insert(key, toJsonValue(v, visitedObjects));
     }
@@ -1013,16 +1018,16 @@ QJsonObject JsonObject::toJsonObject(QV4::Object *o, V4ObjectSet &visitedObjects
     return result;
 }
 
-QV4::Value JsonObject::fromJsonArray(ExecutionEngine *engine, const QJsonArray &array)
+QV4::ReturnedValue JsonObject::fromJsonArray(ExecutionEngine *engine, const QJsonArray &array)
 {
     int size = array.size();
     ArrayObject *a = engine->newArrayObject();
     a->arrayReserve(size);
     a->arrayDataLen = size;
     for (int i = 0; i < size; i++)
-        a->arrayData[i].value = fromJsonValue(engine, array.at(i));
+        a->arrayData[i].value = Value::fromReturnedValue(fromJsonValue(engine, array.at(i)));
     a->setArrayLengthUnchecked(size);
-    return Value::fromObject(a);
+    return Value::fromObject(a).asReturnedValue();
 }
 
 QJsonArray JsonObject::toJsonArray(ArrayObject *a, V4ObjectSet &visitedObjects)
diff --git a/src/qml/jsruntime/qv4jsonobject_p.h b/src/qml/jsruntime/qv4jsonobject_p.h
index e68236622a..821cffcc7c 100644
--- a/src/qml/jsruntime/qv4jsonobject_p.h
+++ b/src/qml/jsruntime/qv4jsonobject_p.h
@@ -59,9 +59,9 @@ public:
     static ReturnedValue method_parse(SimpleCallContext *ctx);
     static ReturnedValue method_stringify(SimpleCallContext *ctx);
 
-    static QV4::Value fromJsonValue(ExecutionEngine *engine, const QJsonValue &value);
-    static QV4::Value fromJsonObject(ExecutionEngine *engine, const QJsonObject &object);
-    static QV4::Value fromJsonArray(ExecutionEngine *engine, const QJsonArray &array);
+    static ReturnedValue fromJsonValue(ExecutionEngine *engine, const QJsonValue &value);
+    static ReturnedValue fromJsonObject(ExecutionEngine *engine, const QJsonObject &object);
+    static ReturnedValue fromJsonArray(ExecutionEngine *engine, const QJsonArray &array);
 
     static inline QJsonValue toJsonValue(const QV4::Value &value)
     { V4ObjectSet visitedObjects; return toJsonValue(value, visitedObjects); }
diff --git a/src/qml/jsruntime/qv4object.cpp b/src/qml/jsruntime/qv4object.cpp
index cec9ee3761..7b372a4e17 100644
--- a/src/qml/jsruntime/qv4object.cpp
+++ b/src/qml/jsruntime/qv4object.cpp
@@ -1127,7 +1127,7 @@ void Object::copyArrayData(Object *other)
 }
 
 
-Value Object::arrayIndexOf(Value v, uint fromIndex, uint endIndex, ExecutionContext *ctx, Object *o)
+ReturnedValue Object::arrayIndexOf(Value v, uint fromIndex, uint endIndex, ExecutionContext *ctx, Object *o)
 {
     Scope scope(engine());
     ScopedValue value(scope);
@@ -1138,13 +1138,13 @@ Value Object::arrayIndexOf(Value v, uint fromIndex, uint endIndex, ExecutionCont
             bool exists;
             value = o->getIndexed(i, &exists);
             if (exists && __qmljs_strict_equal(value, ValueRef(&v)))
-                return Value::fromDouble(i);
+                return Encode(i);
         }
     } else if (sparseArray) {
         for (SparseArrayNode *n = sparseArray->lowerBound(fromIndex); n != sparseArray->end() && n->key() < endIndex; n = n->nextNode()) {
             value = o->getValue(arrayData + n->value, arrayAttributes ? arrayAttributes[n->value] : Attr_Data);
             if (__qmljs_strict_equal(value, ValueRef(&v)))
-                return Value::fromDouble(n->key());
+                return Encode(n->key());
         }
     } else {
         if ((int) endIndex > arrayDataLen)
@@ -1156,12 +1156,12 @@ Value Object::arrayIndexOf(Value v, uint fromIndex, uint endIndex, ExecutionCont
             if (!arrayAttributes || !arrayAttributes[pd - arrayData].isGeneric()) {
                 value = o->getValue(pd, arrayAttributes ? arrayAttributes[pd - arrayData] : Attr_Data);
                 if (__qmljs_strict_equal(value, ValueRef(&v)))
-                    return Value::fromDouble(pd - arrayData);
+                    return Encode((uint)(pd - arrayData));
             }
             ++pd;
         }
     }
-    return Value::fromInt32(-1);
+    return Encode(-1);
 }
 
 void Object::arrayConcat(const ArrayObject *other)
diff --git a/src/qml/jsruntime/qv4object_p.h b/src/qml/jsruntime/qv4object_p.h
index 983f058148..5ae167d782 100644
--- a/src/qml/jsruntime/qv4object_p.h
+++ b/src/qml/jsruntime/qv4object_p.h
@@ -277,7 +277,7 @@ public:
 
     void arrayConcat(const ArrayObject *other);
     void arraySort(ExecutionContext *context, Object *thisObject, const Value &comparefn, uint arrayDataLen);
-    Value arrayIndexOf(Value v, uint fromIndex, uint arrayDataLen, ExecutionContext *ctx, Object *o);
+    ReturnedValue arrayIndexOf(Value v, uint fromIndex, uint arrayDataLen, ExecutionContext *ctx, Object *o);
 
     void arrayReserve(uint n);
     void ensureArrayAttributes();
@@ -350,7 +350,7 @@ struct ForEachIteratorObject: Object {
         type = Type_ForeachIteratorObject;
     }
 
-    Value nextPropertyName() { return it.nextPropertyNameAsString(); }
+    ReturnedValue nextPropertyName() { return it.nextPropertyNameAsString(); }
 
 protected:
     static void markObjects(Managed *that);
diff --git a/src/qml/jsruntime/qv4objectiterator.cpp b/src/qml/jsruntime/qv4objectiterator.cpp
index 8fdf281c7f..f03c2d6b86 100644
--- a/src/qml/jsruntime/qv4objectiterator.cpp
+++ b/src/qml/jsruntime/qv4objectiterator.cpp
@@ -92,38 +92,38 @@ Property *ObjectIterator::next(String **name, uint *index, PropertyAttributes *a
     return 0;
 }
 
-Value ObjectIterator::nextPropertyName(Value *value)
+ReturnedValue ObjectIterator::nextPropertyName(Value *value)
 {
     PropertyAttributes attrs;
     uint index;
     String *name;
     Property *p = next(&name, &index, &attrs);
     if (!p)
-        return Value::nullValue();
+        return Encode::null();
 
     if (value)
         *value = Value::fromReturnedValue(object->getValue(p, attrs));
 
     if (name)
-        return Value::fromString(name);
+        return Value::fromString(name).asReturnedValue();
     assert(index < UINT_MAX);
-    return Value::fromDouble(index);
+    return Encode(index);
 }
 
-Value ObjectIterator::nextPropertyNameAsString(Value *value)
+ReturnedValue ObjectIterator::nextPropertyNameAsString(Value *value)
 {
     PropertyAttributes attrs;
     uint index;
     String *name;
     Property *p = next(&name, &index, &attrs);
     if (!p)
-        return Value::nullValue();
+        return Encode::null();
 
     if (value)
         *value = Value::fromReturnedValue(object->getValue(p, attrs));
 
     if (name)
-        return Value::fromString(name);
+        return Value::fromString(name).asReturnedValue();
     assert(index < UINT_MAX);
-    return Value::fromString(object->engine()->newString(QString::number(index)));
+    return Value::fromString(object->engine()->newString(QString::number(index))).asReturnedValue();
 }
diff --git a/src/qml/jsruntime/qv4objectiterator_p.h b/src/qml/jsruntime/qv4objectiterator_p.h
index 95439397f5..d5464891f1 100644
--- a/src/qml/jsruntime/qv4objectiterator_p.h
+++ b/src/qml/jsruntime/qv4objectiterator_p.h
@@ -76,8 +76,8 @@ struct Q_QML_EXPORT ObjectIterator
 
     ObjectIterator(Object *o, uint flags);
     Property *next(String **name, uint *index, PropertyAttributes *attributes = 0);
-    Value nextPropertyName(Value *value = 0);
-    Value nextPropertyNameAsString(Value *value = 0);
+    ReturnedValue nextPropertyName(Value *value = 0);
+    ReturnedValue nextPropertyNameAsString(Value *value = 0);
 };
 
 }
diff --git a/src/qml/jsruntime/qv4objectproto.cpp b/src/qml/jsruntime/qv4objectproto.cpp
index da66b2436b..fe041f0bd7 100644
--- a/src/qml/jsruntime/qv4objectproto.cpp
+++ b/src/qml/jsruntime/qv4objectproto.cpp
@@ -352,14 +352,16 @@ ReturnedValue ObjectPrototype::method_keys(SimpleCallContext *ctx)
     if (!ctx->argument(0).isObject())
         ctx->throwTypeError();
 
+    Scope scope(ctx);
     Object *o = ctx->argument(0).objectValue();
 
     ArrayObject *a = ctx->engine->newArrayObject();
 
     ObjectIterator it(o, ObjectIterator::EnumerableOnly);
+    ScopedValue name(scope);
     while (1) {
-        Value name = it.nextPropertyNameAsString();
-        if (name.isNull())
+        name = it.nextPropertyNameAsString();
+        if (name->isNull())
             break;
         a->push_back(name);
     }
@@ -605,15 +607,17 @@ ReturnedValue ObjectPrototype::fromPropertyDescriptor(ExecutionContext *ctx, con
 
 ArrayObject *ObjectPrototype::getOwnPropertyNames(ExecutionEngine *v4, const Value &o)
 {
+    Scope scope(v4);
     ArrayObject *array = v4->newArrayObject();
     Object *O = o.asObject();
     if (!O)
         return array;
 
     ObjectIterator it(O, ObjectIterator::NoFlags);
+    ScopedValue name(scope);
     while (1) {
-        Value name = it.nextPropertyNameAsString();
-        if (name.isNull())
+        name = it.nextPropertyNameAsString();
+        if (name->isNull())
             break;
         array->push_back(name);
     }
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index 438465ef9b..91adf7d3e3 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -138,30 +138,16 @@ struct ReadAccessor {
     }
 };
 
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *, int v)
-{ return QV4::Value::fromInt32(v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *, uint v)
-{ return QV4::Value::fromUInt32(v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *, bool v)
-{ return QV4::Value::fromBoolean(v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *e, const QString &v)
-{ return QV4::Value::fromString(e, v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *, float v)
-{ return QV4::Value::fromDouble(v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *, double v)
-{ return QV4::Value::fromDouble(v); }
-static inline QV4::Value valueToHandle(QV4::ExecutionEngine *e, QObject *v)
-{ return QV4::QObjectWrapper::wrap(e, v); }
-
 // Load value properties
 template<void (*ReadFunction)(QObject *, const QQmlPropertyData &,
                               void *, QQmlNotifier **)>
-static QV4::Value LoadProperty(QV8Engine *engine, QObject *object,
+static QV4::ReturnedValue LoadProperty(QV8Engine *engine, QObject *object,
                                           const QQmlPropertyData &property,
                                           QQmlNotifier **notifier)
 {
     Q_ASSERT(!property.isFunction());
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine);
+    QV4::Scope scope(v4);
 
     if (property.isQObject()) {
         QObject *rv = 0;
@@ -172,35 +158,35 @@ static QV4::Value LoadProperty(QV8Engine *engine, QObject *object,
     } else if (property.propType == QMetaType::QReal) {
         qreal v = 0;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.propType == QMetaType::Int || property.isEnum()) {
         int v = 0;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.propType == QMetaType::Bool) {
         bool v = false;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.propType == QMetaType::QString) {
         QString v;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return Value::fromString(v4, v).asReturnedValue();
     } else if (property.propType == QMetaType::UInt) {
         uint v = 0;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.propType == QMetaType::Float) {
         float v = 0;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.propType == QMetaType::Double) {
         double v = 0;
         ReadFunction(object, property, &v, notifier);
-        return valueToHandle(v4, v);
+        return QV4::Encode(v);
     } else if (property.isV4Handle()) {
         QQmlV4Handle handle;
         ReadFunction(object, property, &handle, notifier);
-        return handle.toValue();
+        return handle.toValue().asReturnedValue();
     } else if (property.propType == qMetaTypeId<QJSValue>()) {
         QJSValue v;
         ReadFunction(object, property, &v, notifier);
@@ -225,16 +211,16 @@ static QV4::Value LoadProperty(QV8Engine *engine, QObject *object,
 
         // see if it's a sequence type
         bool succeeded = false;
-        QV4::Value retn = QV4::SequencePrototype::newSequence(v4, property.propType, object, property.coreIndex, &succeeded);
+        QV4::ScopedValue retn(scope, QV4::SequencePrototype::newSequence(v4, property.propType, object, property.coreIndex, &succeeded));
         if (succeeded)
-            return retn;
+            return retn.asReturnedValue();
     }
 
     if (property.propType == QMetaType::UnknownType) {
         QMetaProperty p = object->metaObject()->property(property.coreIndex);
         qWarning("QMetaProperty::read: Unable to handle unregistered datatype '%s' for property "
                  "'%s::%s'", p.typeName(), object->metaObject()->className(), p.name());
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     } else {
         QVariant v(property.propType, (void *)0);
         ReadFunction(object, property, v.data(), notifier);
@@ -271,20 +257,23 @@ QQmlPropertyData *QObjectWrapper::findProperty(ExecutionEngine *engine, QQmlCont
     return result;
 }
 
-Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, String *name, QObjectWrapper::RevisionMode revisionMode, bool *hasProperty, bool includeImports)
+ReturnedValue QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, String *name, QObjectWrapper::RevisionMode revisionMode,
+                                             bool *hasProperty, bool includeImports)
 {
     if (QQmlData::wasDeleted(m_object)) {
         if (hasProperty)
             *hasProperty = false;
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     }
 
+    QV4:Scope scope(ctx);
+
     if (name->isEqualTo(m_destroy) || name->isEqualTo(m_toString)) {
         int index = name->isEqualTo(m_destroy) ? QV4::QObjectMethod::DestroyMethod : QV4::QObjectMethod::ToStringMethod;
-        QV4::Value method = QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, index);
+        QV4::ScopedValue method(scope, QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, index));
         if (hasProperty)
             *hasProperty = true;
-        return method;
+        return method.asReturnedValue();
     }
 
     QQmlPropertyData local;
@@ -301,7 +290,7 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
 
                 if (r.isValid()) {
                     if (r.scriptIndex != -1) {
-                        return QV4::Value::undefinedValue();
+                        return QV4::Encode::undefined();
                     } else if (r.type) {
                         return QmlTypeWrapper::create(ctx->engine->v8Engine, m_object, r.type, QmlTypeWrapper::ExcludeEnums);
                     } else if (r.importNamespace) {
@@ -311,7 +300,7 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
                 }
             }
         }
-        return QV4::Value::fromReturnedValue(QV4::Object::get(this, name, hasProperty));
+        return QV4::Object::get(this, name, hasProperty);
     }
 
     QQmlData::flushPendingBinding(m_object, result->coreIndex);
@@ -321,7 +310,7 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
         if (ddata && ddata->propertyCache && !ddata->propertyCache->isAllowedInRevision(result)) {
             if (hasProperty)
                 *hasProperty = false;
-            return QV4::Value::undefinedValue();
+            return QV4::Encode::undefined();
         }
     }
 
@@ -334,7 +323,8 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
             Q_ASSERT(vmemo);
             return vmemo->vmeMethod(result->coreIndex);
         } else if (result->isV4Function()) {
-            return QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, result->coreIndex, QV4::Value::fromObject(ctx->engine->qmlContextObject()));
+            return QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, result->coreIndex,
+                                              QV4::Value::fromObject(ctx->engine->qmlContextObject())).asReturnedValue();
         } else if (result->isSignalHandler()) {
             QV4::QmlSignalHandler *handler = new (ctx->engine->memoryManager) QV4::QmlSignalHandler(ctx->engine, m_object, result->coreIndex);
 
@@ -343,9 +333,9 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
             handler->put(connect, QV4::Value::fromReturnedValue(ctx->engine->functionClass->prototype->get(connect)));
             handler->put(disconnect, QV4::Value::fromReturnedValue(ctx->engine->functionClass->prototype->get(disconnect)));
 
-            return QV4::Value::fromObject(handler);
+            return QV4::Value::fromObject(handler).asReturnedValue();
         } else {
-            return QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, result->coreIndex);
+            return QV4::QObjectMethod::create(ctx->engine->rootContext, m_object, result->coreIndex).asReturnedValue();
         }
     }
 
@@ -358,15 +348,16 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
         if (ep && ep->propertyCapture && result->accessors->notifier)
             nptr = &n;
 
-        QV4::Value rv = LoadProperty<ReadAccessor::Accessor>(ctx->engine->v8Engine, m_object, *result, nptr);
+        QV4::ScopedValue rv(scope, LoadProperty<ReadAccessor::Accessor>(ctx->engine->v8Engine, m_object, *result, nptr));
 
         if (result->accessors->notifier) {
-            if (n) ep->captureProperty(n);
+            if (n)
+                ep->captureProperty(n);
         } else {
             ep->captureProperty(m_object, result->coreIndex, result->notifyIndex);
         }
 
-        return rv;
+        return rv.asReturnedValue();
     }
 
     if (ep && !result->isConstant())
@@ -383,25 +374,26 @@ Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qml
     }
 }
 
-Value QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, QObject *object, String *name, QObjectWrapper::RevisionMode revisionMode, bool *hasProperty)
+ReturnedValue QObjectWrapper::getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, QObject *object, String *name, QObjectWrapper::RevisionMode revisionMode, bool *hasProperty)
 {
+    QV4::Scope scope(ctx);
     if (QQmlData::wasDeleted(object)) {
         if (hasProperty)
             *hasProperty = false;
-        return QV4::Value::nullValue();
+        return QV4::Encode::null();
     }
 
     if (!QQmlData::get(object, true)) {
         if (hasProperty)
             *hasProperty = false;
-        return QV4::Value::nullValue();
+        return QV4::Encode::null();
     }
 
-    QObjectWrapper *wrapper = wrap(ctx->engine, object).as<QV4::QObjectWrapper>();
+    QV4::Scoped<QObjectWrapper> wrapper(scope, wrap(ctx->engine, object));
     if (!wrapper) {
         if (hasProperty)
             *hasProperty = false;
-        return QV4::Value::nullValue();
+        return QV4::Encode::null();
     }
     return wrapper->getQmlProperty(ctx, qmlContext, name, revisionMode, hasProperty);
 }
@@ -540,57 +532,59 @@ bool QObjectWrapper::setQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlC
     return true;
 }
 
-Value QObjectWrapper::wrap(ExecutionEngine *engine, QObject *object)
+ReturnedValue QObjectWrapper::wrap(ExecutionEngine *engine, QObject *object)
 {
     if (QQmlData::wasDeleted(object))
-        return QV4::Value::nullValue();
+        return QV4::Encode::null();
 
     QQmlData *ddata = QQmlData::get(object, true);
     if (!ddata)
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
+
+    Scope scope(engine);
 
     if (ddata->jsEngineId == engine->m_engineId && !ddata->jsWrapper.isEmpty()) {
         // We own the JS object
-        return ddata->jsWrapper.value();
+        return ddata->jsWrapper.value().asReturnedValue();
     } else if (ddata->jsWrapper.isEmpty() &&
                (ddata->jsEngineId == engine->m_engineId || // We own the QObject
                 ddata->jsEngineId == 0 ||    // No one owns the QObject
                 !ddata->hasTaintedV8Object)) { // Someone else has used the QObject, but it isn't tainted
 
-        QV4::Value rv = create(engine, ddata, object);
+        QV4::ScopedValue rv(scope, create(engine, ddata, object));
         ddata->jsWrapper = rv;
         ddata->jsEngineId = engine->m_engineId;
-        return rv;
+        return rv.asReturnedValue();
 
     } else {
         // If this object is tainted, we have to check to see if it is in our
         // tainted object list
-        Object *alternateWrapper = 0;
+        Scoped<Object> alternateWrapper(scope, 0);
         if (engine->m_multiplyWrappedQObjects && ddata->hasTaintedV8Object)
-            alternateWrapper = engine->m_multiplyWrappedQObjects->value(object);
+            alternateWrapper = Value::fromObject(engine->m_multiplyWrappedQObjects->value(object));
 
         // If our tainted handle doesn't exist or has been collected, and there isn't
         // a handle in the ddata, we can assume ownership of the ddata->v8object
         if (ddata->jsWrapper.isEmpty() && !alternateWrapper) {
-            QV4::Value result = create(engine, ddata, object);
+            QV4::ScopedValue result(scope, create(engine, ddata, object));
             ddata->jsWrapper = result;
             ddata->jsEngineId = engine->m_engineId;
-            return result;
+            return result.asReturnedValue();
         }
 
         if (!alternateWrapper) {
-            alternateWrapper = create(engine, ddata, object).asObject();
+            alternateWrapper = create(engine, ddata, object);
             if (!engine->m_multiplyWrappedQObjects)
                 engine->m_multiplyWrappedQObjects = new MultiplyWrappedQObjectMap;
-            engine->m_multiplyWrappedQObjects->insert(object, alternateWrapper);
+            engine->m_multiplyWrappedQObjects->insert(object, alternateWrapper.getPointer());
             ddata->hasTaintedV8Object = true;
         }
 
-        return QV4::Value::fromObject(alternateWrapper);
+        return alternateWrapper.asReturnedValue();
     }
 }
 
-QV4::Value QObjectWrapper::create(ExecutionEngine *engine, QQmlData *ddata, QObject *object)
+ReturnedValue QObjectWrapper::create(ExecutionEngine *engine, QQmlData *ddata, QObject *object)
 {
     QQmlEngine *qmlEngine = engine->v8Engine->engine();
     if (!ddata->propertyCache && qmlEngine) {
@@ -598,7 +592,7 @@ QV4::Value QObjectWrapper::create(ExecutionEngine *engine, QQmlData *ddata, QObj
         if (ddata->propertyCache) ddata->propertyCache->addref();
     }
 
-    return Value::fromObject(new (engine->memoryManager) QV4::QObjectWrapper(engine, object));
+    return Value::fromObject(new (engine->memoryManager) QV4::QObjectWrapper(engine, object)).asReturnedValue();
 }
 
 QV4::ReturnedValue QObjectWrapper::get(Managed *m, String *name, bool *hasProperty)
@@ -606,7 +600,7 @@ QV4::ReturnedValue QObjectWrapper::get(Managed *m, String *name, bool *hasProper
     QObjectWrapper *that = static_cast<QObjectWrapper*>(m);
     ExecutionEngine *v4 = m->engine();
     QQmlContextData *qmlContext = QV4::QmlContextWrapper::callingContext(v4);
-    return that->getQmlProperty(v4->current, qmlContext, name, IgnoreRevision, hasProperty, /*includeImports*/ true).asReturnedValue();
+    return that->getQmlProperty(v4->current, qmlContext, name, IgnoreRevision, hasProperty, /*includeImports*/ true);
 }
 
 void QObjectWrapper::put(Managed *m, String *name, const Value &value)
@@ -707,9 +701,9 @@ struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
             for (int ii = 0; ii < argCount; ++ii) {
                 int type = argsTypes[ii + 1];
                 if (type == qMetaTypeId<QVariant>()) {
-                    callData->args[ii] = v4->v8Engine->fromVariant(*((QVariant *)metaArgs[ii + 1]));
+                    callData->args[ii] = QV4::Value::fromReturnedValue(v4->v8Engine->fromVariant(*((QVariant *)metaArgs[ii + 1])));
                 } else {
-                    callData->args[ii] = v4->v8Engine->fromVariant(QVariant(type, metaArgs[ii + 1]));
+                    callData->args[ii] = QV4::Value::fromReturnedValue(v4->v8Engine->fromVariant(QVariant(type, metaArgs[ii + 1])));
                 }
             }
 
@@ -968,7 +962,7 @@ struct CallArgument {
 
     inline void initAsType(int type);
     inline void fromValue(int type, QV8Engine *, const QV4::Value&);
-    inline QV4::Value toValue(QV8Engine *);
+    inline ReturnedValue toValue(QV8Engine *);
 
 private:
     CallArgument(const CallArgument &);
@@ -1052,7 +1046,7 @@ static QV4::ReturnedValue CallMethod(QObject *object, int index, int returnType,
 
         QMetaObject::metacall(object, QMetaObject::InvokeMetaMethod, index, argData.data());
 
-        return args[0].toValue(engine).asReturnedValue();
+        return args[0].toValue(engine);
 
     } else if (returnType != QMetaType::Void) {
         
@@ -1063,7 +1057,7 @@ static QV4::ReturnedValue CallMethod(QObject *object, int index, int returnType,
 
         QMetaObject::metacall(object, QMetaObject::InvokeMetaMethod, index, args);
 
-        return arg.toValue(engine).asReturnedValue();
+        return arg.toValue(engine);
 
     } else {
 
@@ -1581,23 +1575,25 @@ void CallArgument::fromValue(int callType, QV8Engine *engine, const QV4::Value &
     }
 }
 
-QV4::Value CallArgument::toValue(QV8Engine *engine)
+QV4::ReturnedValue CallArgument::toValue(QV8Engine *engine)
 {
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine);
+    QV4::Scope scope(v4);
+
     if (type == qMetaTypeId<QJSValue>()) {
         return QJSValuePrivate::get(*qjsValuePtr)->getValue(v4);
     } else if (type == QMetaType::Int) {
-        return QV4::Value::fromInt32(int(intValue));
+        return QV4::Encode(int(intValue));
     } else if (type == QMetaType::UInt) {
-        return QV4::Value::fromUInt32(intValue);
+        return QV4::Encode((uint)intValue);
     } else if (type == QMetaType::Bool) {
-        return QV4::Value::fromBoolean(boolValue);
+        return QV4::Encode(boolValue);
     } else if (type == QMetaType::Double) {
-        return QV4::Value::fromDouble(doubleValue);
+        return QV4::Encode(doubleValue);
     } else if (type == QMetaType::Float) {
-        return QV4::Value::fromDouble(floatValue);
+        return QV4::Encode(floatValue);
     } else if (type == QMetaType::QString) {
-        return engine->toString(*qstringPtr);
+        return engine->toString(*qstringPtr).asReturnedValue();
     } else if (type == QMetaType::QObjectStar) {
         QObject *object = qobjectPtr;
         if (object)
@@ -1611,11 +1607,11 @@ QV4::Value CallArgument::toValue(QV8Engine *engine)
         array->arrayReserve(list.count());
         array->arrayDataLen = list.count();
         for (int ii = 0; ii < list.count(); ++ii)
-            array->arrayData[ii].value = QV4::QObjectWrapper::wrap(v4, list.at(ii));
+            array->arrayData[ii].value = Value::fromReturnedValue(QV4::QObjectWrapper::wrap(v4, list.at(ii)));
         array->setArrayLengthUnchecked(list.count());
-        return QV4::Value::fromObject(array);
+        return QV4::Value::fromObject(array).asReturnedValue();
     } else if (type == qMetaTypeId<QQmlV4Handle>()) {
-        return handlePtr->toValue();
+        return handlePtr->toValue().asReturnedValue();
     } else if (type == QMetaType::QJsonArray) {
         return QV4::JsonObject::fromJsonArray(v4, *jsonArrayPtr);
     } else if (type == QMetaType::QJsonObject) {
@@ -1624,14 +1620,14 @@ QV4::Value CallArgument::toValue(QV8Engine *engine)
         return QV4::JsonObject::fromJsonValue(v4, *jsonValuePtr);
     } else if (type == -1 || type == qMetaTypeId<QVariant>()) {
         QVariant value = *qvariantPtr;
-        QV4::Value rv = engine->fromVariant(value);
-        if (QV4::QObjectWrapper *qobjectWrapper = rv.as<QV4::QObjectWrapper>()) {
+        QV4::ScopedValue rv(scope, engine->fromVariant(value));
+        if (QV4::QObjectWrapper *qobjectWrapper = rv->as<QV4::QObjectWrapper>()) {
             if (QObject *object = qobjectWrapper->object())
                 QQmlData::get(object, true)->setImplicitDestructible();
         }
-        return rv;
+        return rv.asReturnedValue();
     } else {
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     }
 }
 
diff --git a/src/qml/jsruntime/qv4qobjectwrapper_p.h b/src/qml/jsruntime/qv4qobjectwrapper_p.h
index 4c860e1786..95986a4b0d 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper_p.h
+++ b/src/qml/jsruntime/qv4qobjectwrapper_p.h
@@ -85,17 +85,17 @@ struct Q_QML_EXPORT QObjectWrapper : public QV4::Object
 
     QObject *object() const { return m_object.data(); }
 
-    Value getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, String *name, RevisionMode revisionMode, bool *hasProperty = 0, bool includeImports = false);
-    static Value getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, QObject *object, String *name, RevisionMode revisionMode, bool *hasProperty = 0);
+    ReturnedValue getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, String *name, RevisionMode revisionMode, bool *hasProperty = 0, bool includeImports = false);
+    static ReturnedValue getQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, QObject *object, String *name, RevisionMode revisionMode, bool *hasProperty = 0);
 
     static bool setQmlProperty(ExecutionContext *ctx, QQmlContextData *qmlContext, QObject *object, String *name, RevisionMode revisionMode, const Value &value);
 
-    static Value wrap(ExecutionEngine *engine, QObject *object);
+    static ReturnedValue wrap(ExecutionEngine *engine, QObject *object);
 
     using Object::get;
 
 private:
-    static Value create(ExecutionEngine *engine, QQmlData *ddata, QObject *object);
+    static ReturnedValue create(ExecutionEngine *engine, QQmlData *ddata, QObject *object);
 
     QObjectWrapper(ExecutionEngine *engine, QObject *object);
 
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index e17d9b833d..0a8b1b4055 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -755,7 +755,7 @@ ReturnedValue __qmljs_foreach_next_property_name(const ValueRef foreach_iterator
     ForEachIteratorObject *it = static_cast<ForEachIteratorObject *>(foreach_iterator->objectValue());
     Q_ASSERT(it->as<ForEachIteratorObject>());
 
-    return it->nextPropertyName().asReturnedValue();
+    return it->nextPropertyName();
 }
 
 
diff --git a/src/qml/jsruntime/qv4script.cpp b/src/qml/jsruntime/qv4script.cpp
index 0441c3cce6..e3c9505ab7 100644
--- a/src/qml/jsruntime/qv4script.cpp
+++ b/src/qml/jsruntime/qv4script.cpp
@@ -263,12 +263,12 @@ Function *Script::function()
     return vmFunction;
 }
 
-Value Script::qmlBinding()
+ReturnedValue Script::qmlBinding()
 {
     if (!parsed)
         parse();
     QV4::ExecutionEngine *v4 = scope->engine;
-    return Value::fromObject(new (v4->memoryManager) QmlBindingWrapper(scope, vmFunction, qml.value().asObject()));
+    return Value::fromObject(new (v4->memoryManager) QmlBindingWrapper(scope, vmFunction, qml.value().asObject())).asReturnedValue();
 }
 
 QV4::ReturnedValue Script::evaluate(ExecutionEngine *engine,  const QString &script, Object *scopeObject)
diff --git a/src/qml/jsruntime/qv4script_p.h b/src/qml/jsruntime/qv4script_p.h
index b0c863d6be..46f28ccb1e 100644
--- a/src/qml/jsruntime/qv4script_p.h
+++ b/src/qml/jsruntime/qv4script_p.h
@@ -75,7 +75,7 @@ struct Q_QML_EXPORT Script {
 
     void parse();
     ReturnedValue run();
-    Value qmlBinding();
+    ReturnedValue qmlBinding();
 
     Function *function();
 
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index 99c1878a9e..72356204b5 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -571,36 +571,38 @@ bool SequencePrototype::isSequenceType(int sequenceTypeId)
 
 #define NEW_REFERENCE_SEQUENCE(ElementType, ElementTypeName, SequenceType, unused) \
     if (sequenceType == qMetaTypeId<SequenceType>()) { \
-        QV4::Object *obj = new (engine->memoryManager) QQml##ElementTypeName##List(engine, object, propertyIndex); \
-        return QV4::Value::fromObject(obj); \
+        QV4::Scoped<QV4::Object> obj(scope, QV4::Value::fromObject(new (engine->memoryManager) QQml##ElementTypeName##List(engine, object, propertyIndex))); \
+        return obj.asReturnedValue(); \
     } else
 
-QV4::Value SequencePrototype::newSequence(QV4::ExecutionEngine *engine, int sequenceType, QObject *object, int propertyIndex, bool *succeeded)
+ReturnedValue SequencePrototype::newSequence(QV4::ExecutionEngine *engine, int sequenceType, QObject *object, int propertyIndex, bool *succeeded)
 {
+    QV4::Scope scope(engine);
     // This function is called when the property is a QObject Q_PROPERTY of
     // the given sequence type.  Internally we store a typed-sequence
     // (as well as object ptr + property index for updated-read and write-back)
     // and so access/mutate avoids variant conversion.
     *succeeded = true;
-    FOREACH_QML_SEQUENCE_TYPE(NEW_REFERENCE_SEQUENCE) { /* else */ *succeeded = false; return QV4::Value::undefinedValue(); }
+    FOREACH_QML_SEQUENCE_TYPE(NEW_REFERENCE_SEQUENCE) { /* else */ *succeeded = false; return QV4::Encode::undefined(); }
 }
 #undef NEW_REFERENCE_SEQUENCE
 
 #define NEW_COPY_SEQUENCE(ElementType, ElementTypeName, SequenceType, unused) \
     if (sequenceType == qMetaTypeId<SequenceType>()) { \
-        QV4::Object *obj = new (engine->memoryManager) QQml##ElementTypeName##List(engine, v.value<SequenceType >()); \
-        return QV4::Value::fromObject(obj); \
+        QV4::Scoped<QV4::Object> obj(scope, QV4::Value::fromObject(new (engine->memoryManager) QQml##ElementTypeName##List(engine, v.value<SequenceType >()))); \
+        return obj.asReturnedValue(); \
     } else
 
-QV4::Value SequencePrototype::fromVariant(QV4::ExecutionEngine *engine, const QVariant& v, bool *succeeded)
+ReturnedValue SequencePrototype::fromVariant(QV4::ExecutionEngine *engine, const QVariant& v, bool *succeeded)
 {
+    QV4::Scope scope(engine);
     // This function is called when assigning a sequence value to a normal JS var
     // in a JS block.  Internally, we store a sequence of the specified type.
     // Access and mutation is extremely fast since it will not need to modify any
     // QObject property.
     int sequenceType = v.userType();
     *succeeded = true;
-    FOREACH_QML_SEQUENCE_TYPE(NEW_COPY_SEQUENCE) { /* else */ *succeeded = false; return QV4::Value::undefinedValue(); }
+    FOREACH_QML_SEQUENCE_TYPE(NEW_COPY_SEQUENCE) { /* else */ *succeeded = false; return QV4::Encode::undefined(); }
 }
 #undef NEW_COPY_SEQUENCE
 
diff --git a/src/qml/jsruntime/qv4sequenceobject_p.h b/src/qml/jsruntime/qv4sequenceobject_p.h
index 2a81f81d26..f2d06d8918 100644
--- a/src/qml/jsruntime/qv4sequenceobject_p.h
+++ b/src/qml/jsruntime/qv4sequenceobject_p.h
@@ -69,7 +69,7 @@ struct SequencePrototype : public QV4::Object
 
     void init(QV4::ExecutionEngine *engine);
 
-    static QV4::ReturnedValue method_valueOf(QV4::SimpleCallContext *ctx)
+    static ReturnedValue method_valueOf(QV4::SimpleCallContext *ctx)
     {
         return QV4::Value::fromString(ctx->thisObject.toString(ctx)).asReturnedValue();
     }
@@ -77,8 +77,8 @@ struct SequencePrototype : public QV4::Object
     static ReturnedValue method_sort(QV4::SimpleCallContext *ctx);
 
     static bool isSequenceType(int sequenceTypeId);
-    static QV4::Value newSequence(QV4::ExecutionEngine *engine, int sequenceTypeId, QObject *object, int propertyIndex, bool *succeeded);
-    static QV4::Value fromVariant(QV4::ExecutionEngine *engine, const QVariant& v, bool *succeeded);
+    static ReturnedValue newSequence(QV4::ExecutionEngine *engine, int sequenceTypeId, QObject *object, int propertyIndex, bool *succeeded);
+    static ReturnedValue fromVariant(QV4::ExecutionEngine *engine, const QVariant& v, bool *succeeded);
     static int metaTypeForSequence(QV4::Object *object);
     static QVariant toVariant(QV4::Object *object);
     static QVariant toVariant(const QV4::Value &array, int typeHint, bool *succeeded);
diff --git a/src/qml/jsruntime/qv4serialize.cpp b/src/qml/jsruntime/qv4serialize.cpp
index 0bd3f79a5b..b1bdec10df 100644
--- a/src/qml/jsruntime/qv4serialize.cpp
+++ b/src/qml/jsruntime/qv4serialize.cpp
@@ -287,28 +287,29 @@ void Serialize::serialize(QByteArray &data, const QV4::Value &v, QV8Engine *engi
     }
 }
 
-QV4::Value Serialize::deserialize(const char *&data, QV8Engine *engine)
+ReturnedValue Serialize::deserialize(const char *&data, QV8Engine *engine)
 {
     quint32 header = popUint32(data);
     Type type = headertype(header);
 
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine);
+    Scope scope(v4);
 
     switch (type) {
     case WorkerUndefined:
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     case WorkerNull:
-        return QV4::Value::nullValue();
+        return QV4::Encode::null();
     case WorkerTrue:
-        return QV4::Value::fromBoolean(true);
+        return QV4::Encode(true);
     case WorkerFalse:
-        return QV4::Value::fromBoolean(false);
+        return QV4::Encode(false);
     case WorkerString:
     {
         quint32 size = headersize(header);
         QString qstr((QChar *)data, size);
         data += ALIGN(size * sizeof(uint16_t));
-        return QV4::Value::fromString(v4->newString(qstr));
+        return QV4::Value::fromString(v4->newString(qstr)).asReturnedValue();
     }
     case WorkerFunction:
         Q_ASSERT(!"Unreachable");
@@ -317,70 +318,79 @@ QV4::Value Serialize::deserialize(const char *&data, QV8Engine *engine)
     {
         quint32 size = headersize(header);
         QV4::ArrayObject *a = v4->newArrayObject();
+        ScopedValue v(scope);
         for (quint32 ii = 0; ii < size; ++ii) {
-            a->putIndexed(ii, deserialize(data, engine));
+            v = deserialize(data, engine);
+            a->putIndexed(ii, v);
         }
-        return QV4::Value::fromObject(a);
+        return QV4::Value::fromObject(a).asReturnedValue();
     }
     case WorkerObject:
     {
         quint32 size = headersize(header);
         QV4::Object *o = v4->newObject();
+        ScopedValue name(scope);
+        ScopedValue value(scope);
         for (quint32 ii = 0; ii < size; ++ii) {
-            QV4::Value name = deserialize(data, engine);
-            QV4::Value value = deserialize(data, engine);
-            o->put(name.asString(), value);
+            name = deserialize(data, engine);
+            value = deserialize(data, engine);
+            o->put(name->asString(), value);
         }
-        return QV4::Value::fromObject(o);
+        return QV4::Value::fromObject(o).asReturnedValue();
     }
     case WorkerInt32:
-        return QV4::Value::fromInt32((qint32)popUint32(data));
+        return QV4::Encode((qint32)popUint32(data));
     case WorkerUint32:
-        return QV4::Value::fromUInt32(popUint32(data));
+        return QV4::Encode(popUint32(data));
     case WorkerNumber:
-        return QV4::Value::fromDouble(popDouble(data));
+        return QV4::Encode(popDouble(data));
     case WorkerDate:
-        return QV4::Value::fromObject(v4->newDateObject(QV4::Value::fromDouble(popDouble(data))));
+        return QV4::Value::fromObject(v4->newDateObject(QV4::Value::fromDouble(popDouble(data)))).asReturnedValue();
     case WorkerRegexp:
     {
         quint32 flags = headersize(header);
         quint32 length = popUint32(data);
         QString pattern = QString((QChar *)data, length - 1);
         data += ALIGN(length * sizeof(uint16_t));
-        return QV4::Value::fromObject(v4->newRegExpObject(pattern, flags));
+        return QV4::Value::fromObject(v4->newRegExpObject(pattern, flags)).asReturnedValue();
     }
     case WorkerListModel:
     {
         void *ptr = popPtr(data);
         QQmlListModelWorkerAgent *agent = (QQmlListModelWorkerAgent *)ptr;
-        QV4::Value rv = QV4::QObjectWrapper::wrap(v4, agent);
+        QV4::ScopedValue rv(scope, QV4::QObjectWrapper::wrap(v4, agent));
         // ### Find a better solution then the ugly property
         QQmlListModelWorkerAgent::VariantRef ref(agent);
         QVariant var = qVariantFromValue(ref);
-        rv.asObject()->defineReadonlyProperty(v4->newString("__qml:hidden:ref"), engine->fromVariant(var));
+        QV4::ScopedValue v(scope, engine->fromVariant((var)));
+        rv->asObject()->defineReadonlyProperty(v4->newString("__qml:hidden:ref"), v);
 
         agent->release();
         agent->setV8Engine(engine);
-        return rv;
+        return rv.asReturnedValue();
     }
     case WorkerSequence:
     {
+        ScopedValue value(scope);
         bool succeeded = false;
         quint32 length = headersize(header);
         quint32 seqLength = length - 1;
-        int sequenceType = deserialize(data, engine).integerValue();
+        value = deserialize(data, engine);
+        int sequenceType = value->integerValue();
         QV4::ArrayObject *array = v4->newArrayObject();
         array->arrayReserve(seqLength);
         array->arrayDataLen = seqLength;
-        for (quint32 ii = 0; ii < seqLength; ++ii)
-            array->arrayData[ii].value = deserialize(data, engine);
+        for (quint32 ii = 0; ii < seqLength; ++ii) {
+            value = deserialize(data, engine);
+            array->arrayData[ii].value = value;
+        }
         array->setArrayLengthUnchecked(seqLength);
         QVariant seqVariant = QV4::SequencePrototype::toVariant(QV4::Value::fromObject(array), sequenceType, &succeeded);
         return QV4::SequencePrototype::fromVariant(v4, seqVariant, &succeeded);
     }
     }
     Q_ASSERT(!"Unreachable");
-    return QV4::Value::undefinedValue();
+    return QV4::Encode::undefined();
 }
 
 QByteArray Serialize::serialize(const QV4::Value &value, QV8Engine *engine)
@@ -390,7 +400,7 @@ QByteArray Serialize::serialize(const QV4::Value &value, QV8Engine *engine)
     return rv;
 }
 
-QV4::Value Serialize::deserialize(const QByteArray &data, QV8Engine *engine)
+ReturnedValue Serialize::deserialize(const QByteArray &data, QV8Engine *engine)
 {
     const char *stream = data.constData();
     return deserialize(stream, engine);
diff --git a/src/qml/jsruntime/qv4serialize_p.h b/src/qml/jsruntime/qv4serialize_p.h
index 5a04c9d25f..caedb962b1 100644
--- a/src/qml/jsruntime/qv4serialize_p.h
+++ b/src/qml/jsruntime/qv4serialize_p.h
@@ -66,11 +66,11 @@ class Serialize {
 public:
 
     static QByteArray serialize(const Value &, QV8Engine *);
-    static Value deserialize(const QByteArray &, QV8Engine *);
+    static ReturnedValue deserialize(const QByteArray &, QV8Engine *);
 
 private:
     static void serialize(QByteArray &, const Value &, QV8Engine *);
-    static Value deserialize(const char *&, QV8Engine *);
+    static ReturnedValue deserialize(const char *&, QV8Engine *);
 };
 
 }
diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index eff17ddd9a..a5e281dc56 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -244,12 +244,13 @@ void QQmlBinding::update(QQmlPropertyPrivate::WriteFlags flags)
 
         } else {
             QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context()->engine);
+            QV4::Scope scope(ep->v4engine());
+
             ep->referenceScarceResources();
 
             bool isUndefined = false;
 
-            QV4::Value result =
-                    QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined);
+            QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined));
 
             trace.event("writing binding result");
 
@@ -285,12 +286,12 @@ void QQmlBinding::update(QQmlPropertyPrivate::WriteFlags flags)
 QVariant QQmlBinding::evaluate()
 {
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context()->engine);
+    QV4::Scope scope(ep->v4engine());
     ep->referenceScarceResources();
 
     bool isUndefined = false;
 
-    QV4::Value result =
-            QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined);
+    QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(context(), v4function.value(), &isUndefined));
 
     ep->dereferenceScarceResources();
 
diff --git a/src/qml/qml/qqmlboundsignal.cpp b/src/qml/qml/qqmlboundsignal.cpp
index b7cb52bdbc..deb93b990d 100644
--- a/src/qml/qml/qqmlboundsignal.cpp
+++ b/src/qml/qml/qqmlboundsignal.cpp
@@ -194,7 +194,7 @@ void QQmlBoundSignalExpression::evaluate(void **a)
             //    for several cases (such as QVariant type and QObject-derived types)
             //args[ii] = engine->metaTypeToJS(type, a[ii + 1]);
             if (type == QMetaType::QVariant) {
-                args[ii] = engine->fromVariant(*((QVariant *)a[ii + 1]));
+                args[ii] = QV4::Value::fromReturnedValue(engine->fromVariant(*((QVariant *)a[ii + 1])));
             } else if (type == QMetaType::Int) {
                 //### optimization. Can go away if we switch to metaTypeToJS, or be expanded otherwise
                 args[ii] = QV4::Value::fromInt32(*reinterpret_cast<const int*>(a[ii + 1]));
@@ -204,9 +204,9 @@ void QQmlBoundSignalExpression::evaluate(void **a)
                 if (!*reinterpret_cast<void* const *>(a[ii + 1]))
                     args[ii] = QV4::Value::nullValue();
                 else
-                    args[ii] = QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1]));
+                    args[ii] = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1])));
             } else {
-                args[ii] = engine->fromVariant(QVariant(type, a[ii + 1]));
+                args[ii] = QV4::Value::fromReturnedValue(engine->fromVariant(QVariant(type, a[ii + 1])));
             }
         }
 
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index eb5e314ead..f822728f08 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -1221,8 +1221,8 @@ void QQmlComponent::createObject(QQmlV4Function *args)
 
     QQmlComponent_setQmlParent(rv, parent);
 
-    QV4::Value object = QV4::QObjectWrapper::wrap(v4engine, rv);
-    Q_ASSERT(object.asObject());
+    QV4::ScopedValue object(scope, QV4::QObjectWrapper::wrap(v4engine, rv));
+    Q_ASSERT(object->isObject());
 
     if (!valuemap.isEmpty()) {
         QQmlComponentExtension *e = componentExtension(v8engine);
@@ -1369,8 +1369,8 @@ void QQmlComponentPrivate::initializeObjectWithInitialProperties(const QV4::Valu
     QV4::ExecutionEngine *v4engine = QV8Engine::getV4(v8engine);
     QV4::Scope scope(v4engine);
 
-    QV4::Value object = QV4::QObjectWrapper::wrap(v4engine, toCreate);
-    Q_ASSERT(object.asObject());
+    QV4::ScopedValue object(scope, QV4::QObjectWrapper::wrap(v4engine, toCreate));
+    Q_ASSERT(object->asObject());
 
     if (!valuemap.isEmpty()) {
         QQmlComponentExtension *e = componentExtension(v8engine);
@@ -1412,7 +1412,7 @@ QV4::ReturnedValue QmlIncubatorObject::method_get_object(QV4::SimpleCallContext
     if (!o)
         ctx->throwTypeError();
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, o->object()).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, o->object());
 }
 
 QV4::ReturnedValue QmlIncubatorObject::method_forceCompletion(QV4::SimpleCallContext *ctx)
@@ -1478,7 +1478,7 @@ void QmlIncubatorObject::setInitialState(QObject *o)
         QV4::Scoped<QV4::FunctionObject> f(scope, QV4::Script::evaluate(v4, QString::fromLatin1(INITIALPROPERTIES_SOURCE), qmlGlobal.asObject()));
         QV4::ScopedCallData callData(scope, 2);
         callData->thisObject = QV4::Value::fromObject(v4->globalObject);
-        callData->args[0] = QV4::QObjectWrapper::wrap(v4, o);
+        callData->args[0] = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(v4, o));
         callData->args[1] = valuemap;
         f->call(callData);
     }
diff --git a/src/qml/qml/qqmlcontextwrapper.cpp b/src/qml/qml/qqmlcontextwrapper.cpp
index f84f288770..50d1f32c10 100644
--- a/src/qml/qml/qqmlcontextwrapper.cpp
+++ b/src/qml/qml/qqmlcontextwrapper.cpp
@@ -73,15 +73,15 @@ QmlContextWrapper::~QmlContextWrapper()
         context->destroy();
 }
 
-QV4::Value QmlContextWrapper::qmlScope(QV8Engine *v8, QQmlContextData *ctxt, QObject *scope)
+ReturnedValue QmlContextWrapper::qmlScope(QV8Engine *v8, QQmlContextData *ctxt, QObject *scope)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
     QmlContextWrapper *w = new (v4->memoryManager) QmlContextWrapper(v8, ctxt, scope);
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
-QV4::Value QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
+ReturnedValue QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -92,7 +92,7 @@ QV4::Value QmlContextWrapper::urlScope(QV8Engine *v8, const QUrl &url)
 
     QmlContextWrapper *w = new (v4->memoryManager) QmlContextWrapper(v8, context, 0);
     w->isNullWrapper = true;
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 QQmlContextData *QmlContextWrapper::callingContext(ExecutionEngine *v4)
@@ -192,9 +192,9 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                 else
                     return QV4::Value::undefinedValue().asReturnedValue();
             } else if (r.type) {
-                return QmlTypeWrapper::create(engine, scopeObject, r.type).asReturnedValue();
+                return QmlTypeWrapper::create(engine, scopeObject, r.type);
             } else if (r.importNamespace) {
-                return QmlTypeWrapper::create(engine, scopeObject, context->imports, r.importNamespace).asReturnedValue();
+                return QmlTypeWrapper::create(engine, scopeObject, context->imports, r.importNamespace);
             }
             Q_ASSERT(!"Unreachable");
         }
@@ -216,7 +216,7 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                     ep->captureProperty(&context->idValues[propertyIdx].bindings);
                     if (hasProperty)
                         *hasProperty = true;
-                    return QV4::QObjectWrapper::wrap(v4, context->idValues[propertyIdx]).asReturnedValue();
+                    return QV4::QObjectWrapper::wrap(v4, context->idValues[propertyIdx]);
                 } else {
 
                     QQmlContextPrivate *cp = context->asQQmlContextPrivate();
@@ -231,9 +231,9 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
                         QQmlListProperty<QObject> prop(context->asQQmlContext(), (void*) qintptr(propertyIdx),
                                                                QQmlContextPrivate::context_count,
                                                                QQmlContextPrivate::context_at);
-                        return QmlListWrapper::create(engine, prop, qMetaTypeId<QQmlListProperty<QObject> >()).asReturnedValue();
+                        return QmlListWrapper::create(engine, prop, qMetaTypeId<QQmlListProperty<QObject> >());
                     } else {
-                        return engine->fromVariant(cp->propertyValues.at(propertyIdx)).asReturnedValue();
+                        return engine->fromVariant(cp->propertyValues.at(propertyIdx));
                     }
                 }
             }
@@ -242,7 +242,8 @@ ReturnedValue QmlContextWrapper::get(Managed *m, String *name, bool *hasProperty
         // Search scope object
         if (scopeObject) {
             bool hasProp = false;
-            QV4::Value result = QV4::QObjectWrapper::getQmlProperty(v4->current, context, scopeObject, name, QV4::QObjectWrapper::CheckRevision, &hasProp);
+            QV4::ScopedValue result(scope, QV4::QObjectWrapper::getQmlProperty(v4->current, context, scopeObject,
+                                                                               name, QV4::QObjectWrapper::CheckRevision, &hasProp));
             if (hasProp) {
                 if (hasProperty)
                     *hasProperty = true;
diff --git a/src/qml/qml/qqmlcontextwrapper_p.h b/src/qml/qml/qqmlcontextwrapper_p.h
index 0ed933014b..c5f7f251c1 100644
--- a/src/qml/qml/qqmlcontextwrapper_p.h
+++ b/src/qml/qml/qqmlcontextwrapper_p.h
@@ -70,8 +70,8 @@ struct Q_QML_EXPORT QmlContextWrapper : Object
     QmlContextWrapper(QV8Engine *engine, QQmlContextData *context, QObject *scopeObject, bool ownsContext = false);
     ~QmlContextWrapper();
 
-    static QV4::Value qmlScope(QV8Engine *e, QQmlContextData *ctxt, QObject *scope);
-    static QV4::Value urlScope(QV8Engine *e, const QUrl &);
+    static ReturnedValue qmlScope(QV8Engine *e, QQmlContextData *ctxt, QObject *scope);
+    static ReturnedValue urlScope(QV8Engine *e, const QUrl &);
 
     static QQmlContextData *callingContext(ExecutionEngine *v4);
     static void takeContextOwnership(const QV4::Value &qmlglobal);
diff --git a/src/qml/qml/qqmlexpression.cpp b/src/qml/qml/qqmlexpression.cpp
index ddebf02c6c..76214c17a4 100644
--- a/src/qml/qml/qqmlexpression.cpp
+++ b/src/qml/qml/qqmlexpression.cpp
@@ -260,7 +260,7 @@ void QQmlExpression::setExpression(const QString &expression)
 }
 
 // Must be called with a valid handle scope
-QV4::Value QQmlExpressionPrivate::v4value(bool *isUndefined)
+QV4::ReturnedValue QQmlExpressionPrivate::v4value(bool *isUndefined)
 {
     if (!expressionFunctionValid) {
         function = qmlBinding(context(), scopeObject(), expression, url, line, &qmlscope);
@@ -285,7 +285,8 @@ QVariant QQmlExpressionPrivate::value(bool *isUndefined)
     ep->referenceScarceResources(); // "hold" scarce resources in memory during evaluation.
 
     {
-        QV4::Value result = v4value(isUndefined);
+        QV4::Scope scope(QV8Engine::getV4(ep->v8engine()));
+        QV4::ScopedValue result(scope, v4value(isUndefined));
         rv = ep->v8engine()->toVariant(result, -1);
     }
 
diff --git a/src/qml/qml/qqmlexpression_p.h b/src/qml/qml/qqmlexpression_p.h
index 9cc5a326f8..e84d193837 100644
--- a/src/qml/qml/qqmlexpression_p.h
+++ b/src/qml/qml/qqmlexpression_p.h
@@ -81,7 +81,7 @@ public:
 
     QVariant value(bool *isUndefined = 0);
 
-    QV4::Value v4value(bool *isUndefined = 0);
+    QV4::ReturnedValue v4value(bool *isUndefined = 0);
 
     static inline QQmlExpressionPrivate *get(QQmlExpression *expr);
     static inline QQmlExpression *get(QQmlExpressionPrivate *expr);
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index 322100f47e..d16d421ed2 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -122,15 +122,13 @@ void QQmlJavaScriptExpression::resetNotifyOnValueChanged()
     clearGuards();
 }
 
-QV4::Value
-QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
+QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
                                    const QV4::Value &function, bool *isUndefined)
 {
     return evaluate(context, function, 0, 0, isUndefined);
 }
 
-QV4::Value
-QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
+QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
                                    const QV4::Value &function,
                                    int argc, QV4::Value *args,
                                    bool *isUndefined)
@@ -140,7 +138,7 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
     if (function.isEmpty() || function.isUndefined()) {
         if (isUndefined)
             *isUndefined = true;
-        return QV4::Value::emptyValue();
+        return QV4::Value::emptyValue().asReturnedValue();
     }
 
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(context->engine);
@@ -167,15 +165,14 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
     QV4::ScopedValue result(scope, QV4::Value::undefinedValue());
     QV4::ExecutionContext *ctx = v4->current;
     try {
-        QV4::Value This = ep->v8engine()->global();
+        QV4::ScopedCallData callData(scope, argc);
+        callData->thisObject = ep->v8engine()->global();
         if (scopeObject() && requiresThisObject()) {
-            QV4::Value value = QV4::QObjectWrapper::wrap(ctx->engine, scopeObject());
-            if (value.isObject())
-                This = value;
+            QV4::ScopedValue value(scope, QV4::QObjectWrapper::wrap(ctx->engine, scopeObject()));
+            if (value->isObject())
+                callData->thisObject = value;
         }
 
-        QV4::ScopedCallData callData(scope, argc);
-        callData->thisObject = This;
         memcpy(callData->args, args, argc*sizeof(QV4::Value));
         result = function.asFunctionObject()->call(callData);
 
@@ -211,7 +208,7 @@ QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
 
     ep->propertyCapture = lastPropertyCapture;
 
-    return result;
+    return result.asReturnedValue();
 }
 
 void QQmlJavaScriptExpression::GuardCapture::captureProperty(QQmlNotifier *n)
@@ -360,7 +357,7 @@ QQmlJavaScriptExpression::evalFunction(QQmlContextData *ctxt, QObject *scopeObje
     return result.asReturnedValue();
 }
 
-QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt, QObject *scope,
+QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt, QObject *qmlScope,
                                                        const QString &code, const QString &filename, quint16 line,
                                                        QV4::PersistentValue *qmlscope)
 {
@@ -369,10 +366,11 @@ QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt,
 
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(ep->v8engine());
     QV4::ExecutionContext *ctx = v4->current;
+    QV4::Scope scope(v4);
 
-    QV4::Value scopeObject = QV4::QmlContextWrapper::qmlScope(ep->v8engine(), ctxt, scope);
-    QV4::Script script(v4, scopeObject.asObject(), code, filename, line);
-    QV4::Value result;
+    QV4::ScopedValue qmlScopeObject(scope, QV4::QmlContextWrapper::qmlScope(ep->v8engine(), ctxt, qmlScope));
+    QV4::Script script(v4, qmlScopeObject->asObject(), code, filename, line);
+    QV4::ScopedValue result(scope);
     try {
         script.parse();
         result = script.qmlBinding();
@@ -386,13 +384,13 @@ QV4::PersistentValue QQmlJavaScriptExpression::qmlBinding(QQmlContextData *ctxt,
             error.setLine(line);
         if (error.url().isEmpty())
             error.setUrl(QUrl::fromLocalFile(filename));
-        error.setObject(scope);
+        error.setObject(qmlScope);
         ep->warning(error);
         return QV4::PersistentValue();
     }
     if (qmlscope)
-        *qmlscope = scopeObject;
-    return result;
+        *qmlscope = qmlScopeObject;
+    return result.asReturnedValue();
 }
 
 
diff --git a/src/qml/qml/qqmljavascriptexpression_p.h b/src/qml/qml/qqmljavascriptexpression_p.h
index ef36a2f91a..f08b3af6cf 100644
--- a/src/qml/qml/qqmljavascriptexpression_p.h
+++ b/src/qml/qml/qqmljavascriptexpression_p.h
@@ -110,9 +110,9 @@ public:
 
     QQmlJavaScriptExpression(VTable *vtable);
 
-    QV4::Value evaluate(QQmlContextData *, const QV4::Value &function,
+    QV4::ReturnedValue evaluate(QQmlContextData *, const QV4::Value &function,
                                   bool *isUndefined);
-    QV4::Value evaluate(QQmlContextData *, const QV4::Value &function,
+    QV4::ReturnedValue evaluate(QQmlContextData *, const QV4::Value &function,
                                   int argc, QV4::Value *args,
                                   bool *isUndefined);
 
diff --git a/src/qml/qml/qqmllistwrapper.cpp b/src/qml/qml/qqmllistwrapper.cpp
index e8f01bbc08..23aca851a6 100644
--- a/src/qml/qml/qqmllistwrapper.cpp
+++ b/src/qml/qml/qqmllistwrapper.cpp
@@ -63,10 +63,10 @@ QmlListWrapper::~QmlListWrapper()
 {
 }
 
-Value QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int propType)
+ReturnedValue QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int propType)
 {
     if (!object || propId == -1)
-        return Value::nullValue();
+        return Encode::null();
 
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -75,10 +75,10 @@ Value QmlListWrapper::create(QV8Engine *v8, QObject *object, int propId, int pro
     r->propertyType = propType;
     void *args[] = { &r->property, 0 };
     QMetaObject::metacall(object, QMetaObject::ReadProperty, propId, args);
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
-Value QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType)
+ReturnedValue QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
@@ -86,7 +86,7 @@ Value QmlListWrapper::create(QV8Engine *v8, const QQmlListProperty<QObject> &pro
     r->object = prop.object;
     r->property = prop;
     r->propertyType = propType;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
 QVariant QmlListWrapper::toVariant() const
@@ -126,7 +126,7 @@ ReturnedValue QmlListWrapper::getIndexed(Managed *m, uint index, bool *hasProper
 
     quint32 count = w->property.count ? w->property.count(&w->property) : 0;
     if (index < count && w->property.at)
-        return QV4::QObjectWrapper::wrap(e, w->property.at(&w->property, index)).asReturnedValue();
+        return QV4::QObjectWrapper::wrap(e, w->property.at(&w->property, index));
 
     return Value::undefinedValue().asReturnedValue();
 }
@@ -156,7 +156,7 @@ Property *QmlListWrapper::advanceIterator(Managed *m, ObjectIterator *it, String
             *attrs = QV4::Attr_Data;
         *index = it->arrayIndex;
         ++it->arrayIndex;
-        it->tmpDynamicProperty.value = QV4::QObjectWrapper::wrap(w->engine(), w->property.at(&w->property, *index));
+        it->tmpDynamicProperty.value = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(w->engine(), w->property.at(&w->property, *index)));
         return &it->tmpDynamicProperty;
     }
     return QV4::Object::advanceIterator(m, it, name, index, attrs);
diff --git a/src/qml/qml/qqmllistwrapper_p.h b/src/qml/qml/qqmllistwrapper_p.h
index 4778443d6b..0de028a35b 100644
--- a/src/qml/qml/qqmllistwrapper_p.h
+++ b/src/qml/qml/qqmllistwrapper_p.h
@@ -76,8 +76,8 @@ protected:
 
 public:
 
-    static Value create(QV8Engine *v8, QObject *object, int propId, int propType);
-    static Value create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType);
+    static ReturnedValue create(QV8Engine *v8, QObject *object, int propId, int propType);
+    static ReturnedValue create(QV8Engine *v8, const QQmlListProperty<QObject> &prop, int propType);
 
     QVariant toVariant() const;
 
diff --git a/src/qml/qml/qqmllocale.cpp b/src/qml/qml/qqmllocale.cpp
index 27c8dff598..38ffc5386d 100644
--- a/src/qml/qml/qqmllocale.cpp
+++ b/src/qml/qml/qqmllocale.cpp
@@ -807,7 +807,7 @@ QQmlLocale::~QQmlLocale()
 {
 }
 
-QV4::Value QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
+QV4::ReturnedValue QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
 {
     QV8LocaleDataDeletable *d = localeV8Data(v8engine);
     QV4::ExecutionEngine *engine = QV8Engine::getV4(v8engine);
@@ -815,7 +815,7 @@ QV4::Value QQmlLocale::locale(QV8Engine *v8engine, const QString &locale)
     if (!locale.isEmpty())
         wrapper->locale = QLocale(locale);
     wrapper->setPrototype(d->prototype.value().asObject());
-    return QV4::Value::fromObject(wrapper);
+    return QV4::Value::fromObject(wrapper).asReturnedValue();
 }
 
 void QQmlLocale::registerStringLocaleCompare(QV4::ExecutionEngine *engine)
diff --git a/src/qml/qml/qqmllocale_p.h b/src/qml/qml/qqmllocale_p.h
index 5088693269..8075bd462f 100644
--- a/src/qml/qml/qqmllocale_p.h
+++ b/src/qml/qml/qqmllocale_p.h
@@ -118,7 +118,7 @@ public:
         Saturday = Qt::Saturday
     };
 
-    static QV4::Value locale(QV8Engine *v8engine, const QString &lang);
+    static QV4::ReturnedValue locale(QV8Engine *v8engine, const QString &lang);
 
     static void registerStringLocaleCompare(QV4::ExecutionEngine *engine);
 
diff --git a/src/qml/qml/qqmltypewrapper.cpp b/src/qml/qml/qqmltypewrapper.cpp
index 8f05a877ef..09ef732e2d 100644
--- a/src/qml/qml/qqmltypewrapper.cpp
+++ b/src/qml/qml/qqmltypewrapper.cpp
@@ -87,19 +87,19 @@ QVariant QmlTypeWrapper::toVariant() const
 
 
 // Returns a type wrapper for type t on o.  This allows access of enums, and attached properties.
-Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlType *t, TypeNameMode mode)
+ReturnedValue QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlType *t, TypeNameMode mode)
 {
     Q_ASSERT(t);
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
 
     QmlTypeWrapper *w = new (v4->memoryManager) QmlTypeWrapper(v8);
     w->mode = mode; w->object = o; w->type = t;
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 // Returns a type wrapper for importNamespace (of t) on o.  This allows nested resolution of a type in a
 // namespace.
-Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, const void *importNamespace, TypeNameMode mode)
+ReturnedValue QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, const void *importNamespace, TypeNameMode mode)
 {
     Q_ASSERT(t);
     Q_ASSERT(importNamespace);
@@ -108,17 +108,20 @@ Value QmlTypeWrapper::create(QV8Engine *v8, QObject *o, QQmlTypeNameCache *t, co
     QmlTypeWrapper *w = new (v4->memoryManager) QmlTypeWrapper(v8);
     w->mode = mode; w->object = o; w->typeNamespace = t; w->importNamespace = importNamespace;
     t->addref();
-    return Value::fromObject(w);
+    return Value::fromObject(w).asReturnedValue();
 }
 
 
 ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
 {
-    QmlTypeWrapper *w = m->as<QmlTypeWrapper>();
     QV4::ExecutionEngine *v4 = m->engine();
+    QV4::Scope scope(v4);
+
+    QmlTypeWrapper *w = m->as<QmlTypeWrapper>();
     if (!w)
         v4->current->throwTypeError();
 
+
     if (hasProperty)
         *hasProperty = true;
 
@@ -155,12 +158,12 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
                 }
 
                 // check for property.
-                return QV4::QObjectWrapper::getQmlProperty(v4->current, context, qobjectSingleton, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty).asReturnedValue();
+                return QV4::QObjectWrapper::getQmlProperty(v4->current, context, qobjectSingleton, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty);
             } else if (!siinfo->scriptApi(e).isUndefined()) {
                 QV4::ExecutionEngine *engine = QV8Engine::getV4(v8engine);
                 // NOTE: if used in a binding, changes will not trigger re-evaluation since non-NOTIFYable.
-                QV4::Object *o = QJSValuePrivate::get(siinfo->scriptApi(e))->getValue(engine).asObject();
-                if (o)
+                QV4::Scoped<Object> o(scope, QJSValuePrivate::get(siinfo->scriptApi(e))->getValue(engine));
+                if (!!o)
                     return o->get(name);
             }
 
@@ -179,7 +182,7 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
             } else if (w->object) {
                 QObject *ao = qmlAttachedPropertiesObjectById(type->attachedPropertiesId(), object);
                 if (ao)
-                    return QV4::QObjectWrapper::getQmlProperty(v4->current, context, ao, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty).asReturnedValue();
+                    return QV4::QObjectWrapper::getQmlProperty(v4->current, context, ao, name, QV4::QObjectWrapper::IgnoreRevision, hasProperty);
 
                 // Fall through to base implementation
             }
@@ -196,16 +199,16 @@ ReturnedValue QmlTypeWrapper::get(Managed *m, String *name, bool *hasProperty)
         if (r.isValid()) {
             QQmlContextData *context = v8engine->callingContext();
             if (r.type) {
-                return create(w->v8, object, r.type, w->mode).asReturnedValue();
+                return create(w->v8, object, r.type, w->mode);
             } else if (r.scriptIndex != -1) {
                 int index = r.scriptIndex;
                 if (index < context->importedScripts.count())
                     return context->importedScripts.at(index).value().asReturnedValue();
             } else if (r.importNamespace) {
-                return create(w->v8, object, context->imports, r.importNamespace).asReturnedValue();
+                return create(w->v8, object, context->imports, r.importNamespace);
             }
 
-            return QV4::Value::undefinedValue().asReturnedValue();
+            return QV4::Encode::undefined();
 
         }
 
diff --git a/src/qml/qml/qqmltypewrapper_p.h b/src/qml/qml/qqmltypewrapper_p.h
index c545e1cc3b..acf6845736 100644
--- a/src/qml/qml/qqmltypewrapper_p.h
+++ b/src/qml/qml/qqmltypewrapper_p.h
@@ -78,8 +78,8 @@ public:
 
     QVariant toVariant() const;
 
-    static QV4::Value create(QV8Engine *, QObject *, QQmlType *, TypeNameMode = IncludeEnums);
-    static QV4::Value create(QV8Engine *, QObject *, QQmlTypeNameCache *, const void *, TypeNameMode = IncludeEnums);
+    static ReturnedValue create(QV8Engine *, QObject *, QQmlType *, TypeNameMode = IncludeEnums);
+    static ReturnedValue create(QV8Engine *, QObject *, QQmlTypeNameCache *, const void *, TypeNameMode = IncludeEnums);
 
 
     static ReturnedValue get(Managed *m, String *name, bool *hasProperty);
diff --git a/src/qml/qml/qqmlvaluetypewrapper.cpp b/src/qml/qml/qqmlvaluetypewrapper.cpp
index d9ee928858..88704d58b3 100644
--- a/src/qml/qml/qqmlvaluetypewrapper.cpp
+++ b/src/qml/qml/qqmlvaluetypewrapper.cpp
@@ -139,7 +139,7 @@ void QmlValueTypeWrapper::initProto(ExecutionEngine *v4)
     v4->qmlExtensions()->valueTypeWrapperPrototype = o;
 }
 
-Value QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property, QQmlValueType *type)
+ReturnedValue QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property, QQmlValueType *type)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
     initProto(v4);
@@ -147,10 +147,10 @@ Value QmlValueTypeWrapper::create(QV8Engine *v8, QObject *object, int property,
     QmlValueTypeReference *r = new (v4->memoryManager) QmlValueTypeReference(v8);
     r->setPrototype(v4->qmlExtensions()->valueTypeWrapperPrototype);
     r->type = type; r->object = object; r->property = property;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
-Value QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValueType *type)
+ReturnedValue QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValueType *type)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(v8);
     initProto(v4);
@@ -158,7 +158,7 @@ Value QmlValueTypeWrapper::create(QV8Engine *v8, const QVariant &value, QQmlValu
     QmlValueTypeCopy *r = new (v4->memoryManager) QmlValueTypeCopy(v8);
     r->setPrototype(v4->qmlExtensions()->valueTypeWrapperPrototype);
     r->type = type; r->value = value;
-    return Value::fromObject(r);
+    return Value::fromObject(r).asReturnedValue();
 }
 
 QVariant QmlValueTypeWrapper::toVariant() const
@@ -301,7 +301,7 @@ ReturnedValue QmlValueTypeWrapper::get(Managed *m, String *name, bool *hasProper
     if (result->isFunction()) {
         // calling a Q_INVOKABLE function of a value type
         QQmlContextData *qmlContext = QV4::QmlContextWrapper::callingContext(v4);
-        return QV4::QObjectWrapper::getQmlProperty(v4->current, qmlContext, r->type, name, QV4::QObjectWrapper::IgnoreRevision).asReturnedValue();
+        return QV4::QObjectWrapper::getQmlProperty(v4->current, qmlContext, r->type, name, QV4::QObjectWrapper::IgnoreRevision);
     }
 
 #define VALUE_TYPE_LOAD(metatype, cpptype, constructor) \
@@ -321,7 +321,7 @@ ReturnedValue QmlValueTypeWrapper::get(Managed *m, String *name, bool *hasProper
     QVariant v(result->propType, (void *)0);
     void *args[] = { v.data(), 0 };
     r->type->qt_metacall(QMetaObject::ReadProperty, result->coreIndex, args);
-    return r->v8->fromVariant(v).asReturnedValue();
+    return r->v8->fromVariant(v);
 #undef VALUE_TYPE_ACCESSOR
 }
 
diff --git a/src/qml/qml/qqmlvaluetypewrapper_p.h b/src/qml/qml/qqmlvaluetypewrapper_p.h
index 2483b8e26b..355000bb39 100644
--- a/src/qml/qml/qqmlvaluetypewrapper_p.h
+++ b/src/qml/qml/qqmlvaluetypewrapper_p.h
@@ -76,8 +76,8 @@ protected:
 
 public:
 
-    static Value create(QV8Engine *v8, QObject *, int, QQmlValueType *);
-    static Value create(QV8Engine *v8, const QVariant &, QQmlValueType *);
+    static ReturnedValue create(QV8Engine *v8, QObject *, int, QQmlValueType *);
+    static ReturnedValue create(QV8Engine *v8, const QVariant &, QQmlValueType *);
 
     QVariant toVariant() const;
     bool isEqual(const QVariant& value);
diff --git a/src/qml/qml/qqmlvme.cpp b/src/qml/qml/qqmlvme.cpp
index e32193e6f6..1a6577d7ad 100644
--- a/src/qml/qml/qqmlvme.cpp
+++ b/src/qml/qml/qqmlvme.cpp
@@ -372,7 +372,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
         // Store a created object in a property.  These all pop from the objects stack.
         QML_STORE_VALUE(StoreObject, QObject *, objects.pop());
         QML_STORE_VALUE(StoreVariantObject, QVariant, QVariant::fromValue(objects.pop()));
-        QML_STORE_VAR(StoreVarObject, QV4::QObjectWrapper::wrap(ep->v4engine(), objects.pop()));
+        QML_STORE_VAR(StoreVarObject, QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(ep->v4engine(), objects.pop())));
 
         // Store a literal value in a corresponding property
         QML_STORE_VALUE(StoreFloat, float, instr.value);
@@ -420,7 +420,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
 
         // Store a literal value in a var property.
         // We deliberately do not use string converters here
-        QML_STORE_VAR(StoreVar, ep->v8engine()->fromVariant(PRIMITIVES.at(instr.value)));
+        QML_STORE_VAR(StoreVar, QV4::Value::fromReturnedValue(ep->v8engine()->fromVariant(PRIMITIVES.at(instr.value))));
         QML_STORE_VAR(StoreVarInteger, QV4::Value::fromInt32(instr.value));
         QML_STORE_VAR(StoreVarDouble, QV4::Value::fromDouble(instr.value));
         QML_STORE_VAR(StoreVarBool, QV4::Value::fromBoolean(instr.value));
@@ -1113,6 +1113,8 @@ QV4::PersistentValue QQmlVME::run(QQmlContextData *parentCtxt, QQmlScriptData *s
     Q_ASSERT(parentCtxt && parentCtxt->engine);
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(parentCtxt->engine);
     QV8Engine *v8engine = ep->v8engine();
+    QV4::ExecutionEngine *v4 = QV8Engine::getV4(parentCtxt->engine);
+    QV4::Scope scope(v4);
 
     if (script->hasError()) {
         ep->warning(script->error());
@@ -1178,7 +1180,7 @@ QV4::PersistentValue QQmlVME::run(QQmlContextData *parentCtxt, QQmlScriptData *s
         return QV4::PersistentValue();
     }
 
-    QV4::Value qmlglobal = QV4::QmlContextWrapper::qmlScope(v8engine, ctxt, 0);
+    QV4::ScopedValue qmlglobal(scope, QV4::QmlContextWrapper::qmlScope(v8engine, ctxt, 0));
     QV4::QmlContextWrapper::takeContextOwnership(qmlglobal);
 
     QV4::ExecutionContext *ctx = QV8Engine::getV4(v8engine)->current;
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index 360528ea7a..488b4a0adf 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -911,8 +911,10 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
 
                 QQmlEnginePrivate *ep = QQmlEnginePrivate::get(ctxt->engine);
                 ep->referenceScarceResources(); // "hold" scarce resources in memory during evaluation.
+                QV4::Scope scope(ep->v4engine());
 
-                QV4::FunctionObject *function = method(id).asFunctionObject();
+
+                QV4::Scoped<QV4::FunctionObject> function(scope, method(id));
                 if (!function) {
                     // The function was not compiled.  There are some exceptional cases which the
                     // expression rewriter does not rewrite properly (e.g., \r-terminated lines
@@ -927,12 +929,11 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
 
                 QQmlVMEMetaData::MethodData *data = metaData->methodData() + id;
 
-                QV4::Scope scope(function->engine());
                 QV4::ScopedCallData callData(scope, data->parameterCount);
                 callData->thisObject = ep->v8engine()->global();
 
                 for (int ii = 0; ii < data->parameterCount; ++ii)
-                    callData->args[ii] = ep->v8engine()->fromVariant(*(QVariant *)a[ii + 1]);
+                    callData->args[ii] = QV4::Value::fromReturnedValue(ep->v8engine()->fromVariant(*(QVariant *)a[ii + 1]));
 
                 QV4::ScopedValue result(scope);
                 QV4::ExecutionContext *ctx = function->engine()->current;
@@ -961,11 +962,11 @@ int QQmlVMEMetaObject::metaCall(QMetaObject::Call c, int _id, void **a)
         return object->qt_metacall(c, _id, a);
 }
 
-QV4::Value QQmlVMEMetaObject::method(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::method(int index)
 {
     if (!ctxt || !ctxt->isValid()) {
         qWarning("QQmlVMEMetaObject: Internal error - attempted to evaluate a function in an invalid context");
-        return QV4::Value::emptyValue();
+        return QV4::Value::emptyValue().asReturnedValue();
     }
 
     if (!v8methods) 
@@ -984,16 +985,16 @@ QV4::Value QQmlVMEMetaObject::method(int index)
                                                                ctxt->urlString, data->lineNumber);
     }
 
-    return v8methods[index];
+    return v8methods[index].value().asReturnedValue();
 }
 
-QV4::Value QQmlVMEMetaObject::readVarProperty(int id)
+QV4::ReturnedValue QQmlVMEMetaObject::readVarProperty(int id)
 {
     Q_ASSERT(id >= firstVarPropertyIndex);
 
     if (ensureVarPropertiesAllocated())
-        return QV4::Value::fromReturnedValue(varProperties.value().asObject()->getIndexed(id - firstVarPropertyIndex));
-    return QV4::Value::emptyValue();
+        return varProperties.value().asObject()->getIndexed(id - firstVarPropertyIndex);
+    return QV4::Value::emptyValue().asReturnedValue();
 }
 
 QVariant QQmlVMEMetaObject::readPropertyAsVariant(int id)
@@ -1070,8 +1071,8 @@ void QQmlVMEMetaObject::writeProperty(int id, const QVariant &value)
 
         // And, if the new value is a scarce resource, we need to ensure that it does not get
         // automatically released by the engine until no other references to it exist.
-        QV4::Value newv = QQmlEnginePrivate::get(ctxt->engine)->v8engine()->fromVariant(value);
-        if (QV4::VariantObject *v = newv.as<QV4::VariantObject>())
+        QV4::ScopedValue newv(scope, QQmlEnginePrivate::get(ctxt->engine)->v8engine()->fromVariant(value));
+        if (QV4::VariantObject *v = newv->as<QV4::VariantObject>())
             v->addVmePropertyReference();
 
         // Write the value and emit change signal as appropriate.
@@ -1150,7 +1151,7 @@ quint16 QQmlVMEMetaObject::vmeMethodLineNumber(int index)
     return data->lineNumber;
 }
 
-QV4::Value QQmlVMEMetaObject::vmeMethod(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::vmeMethod(int index)
 {
     if (index < methodOffset()) {
         Q_ASSERT(parentVMEMetaObject());
@@ -1178,7 +1179,7 @@ void QQmlVMEMetaObject::setVmeMethod(int index, QV4::PersistentValue function)
     v8methods[methodIndex] = function;
 }
 
-QV4::Value QQmlVMEMetaObject::vmeProperty(int index)
+QV4::ReturnedValue QQmlVMEMetaObject::vmeProperty(int index)
 {
     if (index < propOffset()) {
         Q_ASSERT(parentVMEMetaObject());
diff --git a/src/qml/qml/qqmlvmemetaobject_p.h b/src/qml/qml/qqmlvmemetaobject_p.h
index 9824e0d54b..35592c4906 100644
--- a/src/qml/qml/qqmlvmemetaobject_p.h
+++ b/src/qml/qml/qqmlvmemetaobject_p.h
@@ -164,10 +164,10 @@ public:
 
     bool aliasTarget(int index, QObject **target, int *coreIndex, int *valueTypeIndex) const;
     void registerInterceptor(int index, int valueIndex, QQmlPropertyValueInterceptor *interceptor);
-    QV4::Value vmeMethod(int index);
+    QV4::ReturnedValue vmeMethod(int index);
     quint16 vmeMethodLineNumber(int index);
     void setVmeMethod(int index, QV4::PersistentValue function);
-    QV4::Value vmeProperty(int index);
+    QV4::ReturnedValue vmeProperty(int index);
     void setVMEProperty(int index, const QV4::Value &v);
 
     void connectAliasSignal(int index, bool indexInSignalRange);
@@ -217,9 +217,9 @@ public:
     QQmlPropertyValueInterceptor *interceptors;
 
     QV4::PersistentValue *v8methods;
-    QV4::Value method(int);
+    QV4::ReturnedValue method(int);
 
-    QV4::Value readVarProperty(int);
+    QV4::ReturnedValue readVarProperty(int);
     void writeVarProperty(int, const QV4::Value &);
     QVariant readPropertyAsVariant(int);
     void writeProperty(int, const QVariant &);
diff --git a/src/qml/qml/qqmlxmlhttprequest.cpp b/src/qml/qml/qqmlxmlhttprequest.cpp
index 651a2703f3..b7447aee07 100644
--- a/src/qml/qml/qqmlxmlhttprequest.cpp
+++ b/src/qml/qml/qqmlxmlhttprequest.cpp
@@ -100,9 +100,11 @@ static inline QQmlXMLHttpRequestData *xhrdata(QV8Engine *engine)
 static Value constructMeObject(const Value &thisObj, QV8Engine *e)
 {
     ExecutionEngine *v4 = QV8Engine::getV4(e);
+    Scope scope(v4);
     Object *meObj = v4->newObject();
     meObj->put(v4->newString(QStringLiteral("ThisObject")), thisObj);
-    meObj->put(v4->newString(QStringLiteral("ActivationObject")), QmlContextWrapper::qmlScope(e, e->callingContext(), 0));
+    ScopedValue v(scope, QmlContextWrapper::qmlScope(e, e->callingContext(), 0));
+    meObj->put(v4->newString(QStringLiteral("ActivationObject")), v);
     return Value::fromObject(meObj);
 }
 
diff --git a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
index 59457df30c..2a75bf9834 100644
--- a/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
+++ b/src/qml/qml/v8/qqmlbuiltinfunctions.cpp
@@ -202,7 +202,7 @@ ReturnedValue QtObject::method_rgba(QV4::SimpleCallContext *ctx)
     if (a < 0.0) a=0.0;
     if (a > 1.0) a=1.0;
 
-    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromRgbF(r, g, b, a)).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromRgbF(r, g, b, a));
 }
 
 /*!
@@ -231,7 +231,7 @@ ReturnedValue QtObject::method_hsla(QV4::SimpleCallContext *ctx)
     if (a < 0.0) a=0.0;
     if (a > 1.0) a=1.0;
 
-    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromHslF(h, s, l, a)).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QQml_colorProvider()->fromHslF(h, s, l, a));
 }
 
 /*!
@@ -292,7 +292,7 @@ ReturnedValue QtObject::method_rect(QV4::SimpleCallContext *ctx)
     double w = ctx->arguments[2].toNumber();
     double h = ctx->arguments[3].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QRectF(x, y, w, h))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QRectF(x, y, w, h)));
 }
 
 /*!
@@ -307,7 +307,7 @@ ReturnedValue QtObject::method_point(QV4::SimpleCallContext *ctx)
     double x = ctx->arguments[0].toNumber();
     double y = ctx->arguments[1].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QPointF(x, y))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QPointF(x, y)));
 }
 
 /*!
@@ -322,7 +322,7 @@ ReturnedValue QtObject::method_size(QV4::SimpleCallContext *ctx)
     double w = ctx->arguments[0].toNumber();
     double h = ctx->arguments[1].toNumber();
 
-    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QSizeF(w, h))).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(QVariant::fromValue(QSizeF(w, h)));
 }
 
 /*!
@@ -343,7 +343,7 @@ ReturnedValue QtObject::method_font(QV4::SimpleCallContext *ctx)
     QVariant v = QQml_valueTypeProvider()->createVariantFromJsObject(QMetaType::QFont, QQmlV4Handle(ctx->arguments[0]), v8engine, &ok);
     if (!ok)
         V4THROW_ERROR("Qt.font(): Invalid argument: no valid font subproperties specified");
-    return v8engine->fromVariant(v).asReturnedValue();
+    return v8engine->fromVariant(v);
 }
 
 
@@ -363,7 +363,7 @@ ReturnedValue QtObject::method_vector2d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xy };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector2D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector2D, 1, params));
 }
 
 /*!
@@ -382,7 +382,7 @@ ReturnedValue QtObject::method_vector3d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xyz };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector3D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector3D, 1, params));
 }
 
 /*!
@@ -402,7 +402,7 @@ ReturnedValue QtObject::method_vector4d(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { xyzw };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector4D, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QVector4D, 1, params));
 }
 
 /*!
@@ -422,7 +422,7 @@ ReturnedValue QtObject::method_quaternion(QV4::SimpleCallContext *ctx)
 
     const void *params[] = { sxyz };
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QQuaternion, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QQuaternion, 1, params));
 }
 
 /*!
@@ -441,7 +441,7 @@ ReturnedValue QtObject::method_matrix4x4(QV4::SimpleCallContext *ctx)
         QVariant v = QQml_valueTypeProvider()->createVariantFromJsObject(QMetaType::QMatrix4x4, QQmlV4Handle(ctx->arguments[0]), v8engine, &ok);
         if (!ok)
             V4THROW_ERROR("Qt.matrix4x4(): Invalid argument: not a valid matrix4x4 values array");
-        return v8engine->fromVariant(v).asReturnedValue();
+        return v8engine->fromVariant(v);
     }
 
     if (ctx->argumentCount != 16)
@@ -466,7 +466,7 @@ ReturnedValue QtObject::method_matrix4x4(QV4::SimpleCallContext *ctx)
     vals[15] = ctx->arguments[15].toNumber();
 
     const void *params[] = { vals };
-    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QMatrix4x4, 1, params)).asReturnedValue();
+    return v8engine->fromVariant(QQml_valueTypeProvider()->createValueType(QMetaType::QMatrix4x4, 1, params));
 }
 
 /*!
@@ -504,7 +504,7 @@ ReturnedValue QtObject::method_lighter(QV4::SimpleCallContext *ctx)
     if (ctx->argumentCount == 2)
         factor = ctx->arguments[1].toNumber();
 
-    return v8engine->fromVariant(QQml_colorProvider()->lighter(v, factor)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->lighter(v, factor));
 }
 
 /*!
@@ -543,7 +543,7 @@ ReturnedValue QtObject::method_darker(QV4::SimpleCallContext *ctx)
     if (ctx->argumentCount == 2)
         factor = ctx->arguments[1].toNumber();
 
-    return v8engine->fromVariant(QQml_colorProvider()->darker(v, factor)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->darker(v, factor));
 }
 
 /*!
@@ -601,7 +601,7 @@ ReturnedValue QtObject::method_tint(QV4::SimpleCallContext *ctx)
         return QV4::Encode::null();
     }
 
-    return v8engine->fromVariant(QQml_colorProvider()->tint(v1, v2)).asReturnedValue();
+    return v8engine->fromVariant(QQml_colorProvider()->tint(v1, v2));
 }
 
 /*!
@@ -645,7 +645,7 @@ ReturnedValue QtObject::method_formatDate(QV4::SimpleCallContext *ctx)
          formattedDate = date.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedDate)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedDate));
 }
 
 /*!
@@ -694,7 +694,7 @@ ReturnedValue QtObject::method_formatTime(QV4::SimpleCallContext *ctx)
          formattedTime = time.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedTime)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedTime));
 }
 
 /*!
@@ -812,7 +812,7 @@ ReturnedValue QtObject::method_formatDateTime(QV4::SimpleCallContext *ctx)
          formattedDt = dt.toString(enumFormat);
     }
 
-    return v8engine->fromVariant(QVariant::fromValue(formattedDt)).asReturnedValue();
+    return v8engine->fromVariant(QVariant::fromValue(formattedDt));
 }
 
 /*!
@@ -827,7 +827,7 @@ ReturnedValue QtObject::method_openUrlExternally(QV4::SimpleCallContext *ctx)
     QV8Engine *v8engine = ctx->engine->v8Engine;
 
     QUrl url(Value::fromReturnedValue(method_resolvedUrl(ctx)).toQStringNoThrow());
-    return v8engine->fromVariant(QQml_guiProvider()->openUrlExternally(url)).asReturnedValue();
+    return v8engine->fromVariant(QQml_guiProvider()->openUrlExternally(url));
 }
 
 /*!
@@ -863,7 +863,7 @@ ReturnedValue QtObject::method_fontFamilies(SimpleCallContext *ctx)
         V4THROW_ERROR("Qt.fontFamilies(): Invalid arguments");
 
     QV8Engine *v8engine = ctx->engine->v8Engine;
-    return v8engine->fromVariant(QVariant(QQml_guiProvider()->fontFamilies())).asReturnedValue();
+    return v8engine->fromVariant(QVariant(QQml_guiProvider()->fontFamilies()));
 }
 
 /*!
@@ -1039,7 +1039,7 @@ ReturnedValue QtObject::method_createQmlObject(SimpleCallContext *ctx)
 
     Q_ASSERT(obj);
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, obj).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, obj);
 }
 
 /*!
@@ -1133,7 +1133,7 @@ ReturnedValue QtObject::method_createComponent(SimpleCallContext *ctx)
     QQmlData::get(c, true)->explicitIndestructibleSet = false;
     QQmlData::get(c)->indestructible = false;
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, c).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, c);
 }
 
 /*!
@@ -1168,7 +1168,7 @@ ReturnedValue QtObject::method_locale(SimpleCallContext *ctx)
     if (ctx->argumentCount == 1)
         code = ctx->arguments[0].toQStringNoThrow();
 
-    return QQmlLocale::locale(v8engine, code).asReturnedValue();
+    return QQmlLocale::locale(v8engine, code);
 }
 
 namespace {
@@ -1276,7 +1276,7 @@ ReturnedValue QtObject::method_get_platform(SimpleCallContext *ctx)
         // Only allocate a platform object once
         qt->m_platform = new QQmlPlatform(ctx->engine->v8Engine->publicEngine());
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_platform).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_platform);
 }
 
 ReturnedValue QtObject::method_get_application(SimpleCallContext *ctx)
@@ -1293,7 +1293,7 @@ ReturnedValue QtObject::method_get_application(SimpleCallContext *ctx)
         // Only allocate an application object once
         qt->m_application = QQml_guiProvider()->application(ctx->engine->v8Engine->publicEngine());
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_application).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, qt->m_application);
 }
 
 #ifndef QT_NO_IM
@@ -1301,7 +1301,7 @@ ReturnedValue QtObject::method_get_inputMethod(SimpleCallContext *ctx)
 {
     QObject *o = QQml_guiProvider()->inputMethod();
     QQmlEngine::setObjectOwnership(o, QQmlEngine::CppOwnership);
-    return QV4::QObjectWrapper::wrap(ctx->engine, o).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, o);
 }
 #endif
 
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index c377608341..63ab33a457 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -181,7 +181,7 @@ QVariant QV8Engine::toVariant(const QV4::Value &value, int typeHint)
     return toBasicVariant(value);
 }
 
-static QV4::Value arrayFromStringList(QV8Engine *engine, const QStringList &list)
+static QV4::ReturnedValue arrayFromStringList(QV8Engine *engine, const QStringList &list)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::ArrayObject *a = e->newArrayObject();
@@ -191,10 +191,10 @@ static QV4::Value arrayFromStringList(QV8Engine *engine, const QStringList &list
     for (int ii = 0; ii < len; ++ii)
         a->arrayData[ii].value = QV4::Value::fromString(e->newString(list.at(ii)));
     a->setArrayLengthUnchecked(len);
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
-static QV4::Value arrayFromVariantList(QV8Engine *engine, const QVariantList &list)
+static QV4::ReturnedValue arrayFromVariantList(QV8Engine *engine, const QVariantList &list)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::ArrayObject *a = e->newArrayObject();
@@ -202,23 +202,23 @@ static QV4::Value arrayFromVariantList(QV8Engine *engine, const QVariantList &li
     a->arrayReserve(len);
     a->arrayDataLen = len;
     for (int ii = 0; ii < len; ++ii)
-        a->arrayData[ii].value = engine->fromVariant(list.at(ii));
+        a->arrayData[ii].value = QV4::Value::fromReturnedValue(engine->fromVariant(list.at(ii)));
     a->setArrayLengthUnchecked(len);
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
-static QV4::Value objectFromVariantMap(QV8Engine *engine, const QVariantMap &map)
+static QV4::ReturnedValue objectFromVariantMap(QV8Engine *engine, const QVariantMap &map)
 {
     QV4::ExecutionEngine *e = QV8Engine::getV4(engine);
     QV4::Object *o = e->newObject();
     for (QVariantMap::ConstIterator iter = map.begin(); iter != map.end(); ++iter)
-        o->put(e->newString(iter.key()), engine->fromVariant(iter.value()));
-    return QV4::Value::fromObject(o);
+        o->put(e->newString(iter.key()), QV4::Value::fromReturnedValue(engine->fromVariant(iter.value())));
+    return QV4::Value::fromObject(o).asReturnedValue();
 }
 
 Q_CORE_EXPORT QString qt_regexp_toCanonical(const QString &, QRegExp::PatternSyntax);
 
-QV4::Value QV8Engine::fromVariant(const QVariant &variant)
+QV4::ReturnedValue QV8Engine::fromVariant(const QVariant &variant)
 {
     int type = variant.userType();
     const void *ptr = variant.constData();
@@ -227,49 +227,50 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
         switch (QMetaType::Type(type)) {
             case QMetaType::UnknownType:
             case QMetaType::Void:
-                return QV4::Value::undefinedValue();
+                return QV4::Encode::undefined();
             case QMetaType::Bool:
-                return QV4::Value::fromBoolean(*reinterpret_cast<const bool*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const bool*>(ptr));
             case QMetaType::Int:
-                return QV4::Value::fromInt32(*reinterpret_cast<const int*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const int*>(ptr));
             case QMetaType::UInt:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const uint*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const uint*>(ptr));
             case QMetaType::LongLong:
-                return QV4::Value::fromDouble(*reinterpret_cast<const qlonglong*>(ptr));
+                return QV4::Encode((double)*reinterpret_cast<const qlonglong*>(ptr));
             case QMetaType::ULongLong:
-                return QV4::Value::fromDouble(*reinterpret_cast<const qulonglong*>(ptr));
+                return QV4::Encode((double)*reinterpret_cast<const qulonglong*>(ptr));
             case QMetaType::Double:
-                return QV4::Value::fromDouble(*reinterpret_cast<const double*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const double*>(ptr));
             case QMetaType::QString:
-                return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(ptr));
+                return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(ptr)).asReturnedValue();
             case QMetaType::Float:
-                return QV4::Value::fromDouble(*reinterpret_cast<const float*>(ptr));
+                return QV4::Encode(*reinterpret_cast<const float*>(ptr));
             case QMetaType::Short:
-                return QV4::Value::fromInt32(*reinterpret_cast<const short*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const short*>(ptr));
             case QMetaType::UShort:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned short*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const unsigned short*>(ptr));
             case QMetaType::Char:
-                return QV4::Value::fromInt32(*reinterpret_cast<const char*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const char*>(ptr));
             case QMetaType::UChar:
-                return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned char*>(ptr));
+                return QV4::Encode((int)*reinterpret_cast<const unsigned char*>(ptr));
             case QMetaType::QChar:
-                return QV4::Value::fromInt32((*reinterpret_cast<const QChar*>(ptr)).unicode());
+                return QV4::Encode((int)(*reinterpret_cast<const QChar*>(ptr)).unicode());
             case QMetaType::QDateTime:
-                return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(ptr)));
+                return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(ptr))).asReturnedValue();
             case QMetaType::QDate:
-                return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(ptr))));
+                return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(ptr)))).asReturnedValue();
             case QMetaType::QTime:
-            return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(QDate(1970,1,1), *reinterpret_cast<const QTime *>(ptr))));
+            return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(QDate(1970,1,1), *reinterpret_cast<const QTime *>(ptr)))).asReturnedValue();
             case QMetaType::QRegExp:
-                return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(ptr)));
+                return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(ptr))).asReturnedValue();
             case QMetaType::QObjectStar:
                 return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(ptr));
             case QMetaType::QStringList:
                 {
                 bool succeeded = false;
-                QV4::Value retn = QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded);
+                QV4::Scope scope(m_v4Engine);
+                QV4::ScopedValue retn(scope, QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded));
                 if (succeeded)
-                    return retn;
+                    return retn.asReturnedValue();
                 return arrayFromStringList(this, *reinterpret_cast<const QStringList *>(ptr));
                 }
             case QMetaType::QVariantList:
@@ -290,13 +291,14 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
         if (QQmlValueType *vt = QQmlValueTypeFactory::valueType(type))
             return QV4::QmlValueTypeWrapper::create(this, variant, vt);
     } else {
+        QV4::Scope scope(m_v4Engine);
         if (type == qMetaTypeId<QQmlListReference>()) {
             typedef QQmlListReferencePrivate QDLRP;
             QDLRP *p = QDLRP::get((QQmlListReference*)ptr);
             if (p->object) {
                 return QV4::QmlListWrapper::create(this, p->property, p->propertyType);
             } else {
-                return QV4::Value::nullValue();
+                return QV4::Encode::null();
             }
         } else if (type == qMetaTypeId<QJSValue>()) {
             const QJSValue *value = reinterpret_cast<const QJSValue *>(ptr);
@@ -310,9 +312,9 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
             a->arrayReserve(list.count());
             a->arrayDataLen = list.count();
             for (int ii = 0; ii < list.count(); ++ii)
-                a->arrayData[ii].value = QV4::QObjectWrapper::wrap(m_v4Engine, list.at(ii));
+                a->arrayData[ii].value = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(m_v4Engine, list.at(ii)));
             a->setArrayLengthUnchecked(list.count());
-            return QV4::Value::fromObject(a);
+            return QV4::Value::fromObject(a).asReturnedValue();
         } else if (QMetaType::typeFlags(type) & QMetaType::PointerToQObject) {
             return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(ptr));
         }
@@ -323,9 +325,9 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
             return QV4::QObjectWrapper::wrap(m_v4Engine, obj);
 
         bool succeeded = false;
-        QV4::Value retn = QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded);
+        QV4::ScopedValue retn(scope, QV4::SequencePrototype::fromVariant(m_v4Engine, variant, &succeeded));
         if (succeeded)
-            return retn;
+            return retn.asReturnedValue();
 
         if (QQmlValueType *vt = QQmlValueTypeFactory::valueType(type))
             return QV4::QmlValueTypeWrapper::create(this, variant, vt);
@@ -335,7 +337,7 @@ QV4::Value QV8Engine::fromVariant(const QVariant &variant)
     //    + QObjectList
     //    + QList<int>
 
-    return QV4::Value::fromObject(m_v4Engine->newVariantObject(variant));
+    return QV4::Value::fromObject(m_v4Engine->newVariantObject(variant)).asReturnedValue();
 }
 
 QNetworkAccessManager *QV8Engine::networkAccessManager()
@@ -513,15 +515,15 @@ QV4::Value QV8Engine::global()
 // The result is a new Array object with length equal to the length
 // of the QVariantList, and the elements being the QVariantList's
 // elements converted to JS, recursively.
-QV4::Value QV8Engine::variantListToJS(const QVariantList &lst)
+QV4::ReturnedValue QV8Engine::variantListToJS(const QVariantList &lst)
 {
     QV4::ArrayObject *a = m_v4Engine->newArrayObject();
     a->arrayReserve(lst.size());
     a->arrayDataLen = lst.size();
     for (int i = 0; i < lst.size(); i++)
-        a->arrayData[i].value = variantToJS(lst.at(i));
+        a->arrayData[i].value = QV4::Value::fromReturnedValue(variantToJS(lst.at(i)));
     a->setArrayLengthUnchecked(lst.size());
-    return QV4::Value::fromObject(a);
+    return QV4::Value::fromObject(a).asReturnedValue();
 }
 
 // Converts a JS Array object to a QVariantList.
@@ -559,15 +561,15 @@ QVariantList QV8Engine::variantListFromJS(QV4::ArrayObject *a,
 // The result is a new Object object with property names being
 // the keys of the QVariantMap, and values being the values of
 // the QVariantMap converted to JS, recursively.
-QV4::Value QV8Engine::variantMapToJS(const QVariantMap &vmap)
+QV4::ReturnedValue QV8Engine::variantMapToJS(const QVariantMap &vmap)
 {
     QV4::Object *o = m_v4Engine->newObject();
     QVariantMap::const_iterator it;
     for (it = vmap.constBegin(); it != vmap.constEnd(); ++it) {
         QV4::Property *p = o->insertMember(m_v4Engine->newIdentifier(it.key()), QV4::Attr_Data);
-        p->value = variantToJS(it.value());
+        p->value = QV4::Value::fromReturnedValue(variantToJS(it.value()));
     }
-    return QV4::Value::fromObject(o);
+    return QV4::Value::fromObject(o).asReturnedValue();
 }
 
 // Converts a JS Object to a QVariantMap.
@@ -588,17 +590,19 @@ QVariantMap QV8Engine::variantMapFromJS(QV4::Object *o,
         // empty object (and no error is thrown).
         return result;
     }
+    QV4::Scope scope(o->engine());
 
     visitedObjects.insert(o);
 
     QV4::ObjectIterator it(o, QV4::ObjectIterator::EnumerableOnly);
+    QV4::ScopedValue name(scope);
     while (1) {
         QV4::Value v;
-        QV4::Value name = it.nextPropertyNameAsString(&v);
-        if (name.isNull())
+        name = it.nextPropertyNameAsString(&v);
+        if (name->isNull())
             break;
 
-        QString key = name.toQStringNoThrow();
+        QString key = name->toQStringNoThrow();
         result.insert(key, variantFromJS(v, visitedObjects));
     }
 
@@ -608,96 +612,85 @@ QVariantMap QV8Engine::variantMapFromJS(QV4::Object *o,
 
 // Converts the meta-type defined by the given type and data to JS.
 // Returns the value if conversion succeeded, an empty handle otherwise.
-QV4::Value QV8Engine::metaTypeToJS(int type, const void *data)
+QV4::ReturnedValue QV8Engine::metaTypeToJS(int type, const void *data)
 {
     Q_ASSERT(data != 0);
-    QV4::Value result;
 
     // check if it's one of the types we know
     switch (QMetaType::Type(type)) {
     case QMetaType::UnknownType:
     case QMetaType::Void:
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
     case QMetaType::Bool:
-        return QV4::Value::fromBoolean(*reinterpret_cast<const bool*>(data));
+        return QV4::Encode(*reinterpret_cast<const bool*>(data));
     case QMetaType::Int:
-        return QV4::Value::fromInt32(*reinterpret_cast<const int*>(data));
+        return QV4::Encode(*reinterpret_cast<const int*>(data));
     case QMetaType::UInt:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const uint*>(data));
+        return QV4::Encode(*reinterpret_cast<const uint*>(data));
     case QMetaType::LongLong:
-        return QV4::Value::fromDouble(double(*reinterpret_cast<const qlonglong*>(data)));
+        return QV4::Encode(double(*reinterpret_cast<const qlonglong*>(data)));
     case QMetaType::ULongLong:
 #if defined(Q_OS_WIN) && defined(_MSC_FULL_VER) && _MSC_FULL_VER <= 12008804
 #pragma message("** NOTE: You need the Visual Studio Processor Pack to compile support for 64bit unsigned integers.")
-        return QV4::Value::fromDouble(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
 #elif defined(Q_CC_MSVC) && !defined(Q_CC_MSVC_NET)
-        return QV4::Value::fromDouble(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double((qlonglong)*reinterpret_cast<const qulonglong*>(data)));
 #else
-        return QV4::Value::fromDouble(double(*reinterpret_cast<const qulonglong*>(data)));
+        return QV4::Encode(double(*reinterpret_cast<const qulonglong*>(data)));
 #endif
     case QMetaType::Double:
-        return QV4::Value::fromDouble(*reinterpret_cast<const double*>(data));
+        return QV4::Encode(*reinterpret_cast<const double*>(data));
     case QMetaType::QString:
-        return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(data));
+        return QV4::Value::fromString(m_v4Engine->current, *reinterpret_cast<const QString*>(data)).asReturnedValue();
     case QMetaType::Float:
-        return QV4::Value::fromDouble(*reinterpret_cast<const float*>(data));
+        return QV4::Encode(*reinterpret_cast<const float*>(data));
     case QMetaType::Short:
-        return QV4::Value::fromInt32(*reinterpret_cast<const short*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const short*>(data));
     case QMetaType::UShort:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned short*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const unsigned short*>(data));
     case QMetaType::Char:
-        return QV4::Value::fromInt32(*reinterpret_cast<const char*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const char*>(data));
     case QMetaType::UChar:
-        return QV4::Value::fromUInt32(*reinterpret_cast<const unsigned char*>(data));
+        return QV4::Encode((int)*reinterpret_cast<const unsigned char*>(data));
     case QMetaType::QChar:
-        return QV4::Value::fromUInt32((*reinterpret_cast<const QChar*>(data)).unicode());
+        return QV4::Encode((int)(*reinterpret_cast<const QChar*>(data)).unicode());
     case QMetaType::QStringList:
-        result = QV4::Value::fromObject(m_v4Engine->newArrayObject(*reinterpret_cast<const QStringList *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newArrayObject(*reinterpret_cast<const QStringList *>(data))).asReturnedValue();
     case QMetaType::QVariantList:
-        result = variantListToJS(*reinterpret_cast<const QVariantList *>(data));
-        break;
+        return variantListToJS(*reinterpret_cast<const QVariantList *>(data));
     case QMetaType::QVariantMap:
-        result = variantMapToJS(*reinterpret_cast<const QVariantMap *>(data));
-        break;
+        return variantMapToJS(*reinterpret_cast<const QVariantMap *>(data));
     case QMetaType::QDateTime:
-        result = QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newDateObject(*reinterpret_cast<const QDateTime *>(data))).asReturnedValue();
     case QMetaType::QDate:
-        result = QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(data))));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newDateObject(QDateTime(*reinterpret_cast<const QDate *>(data)))).asReturnedValue();
     case QMetaType::QRegExp:
-        result = QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(data)));
-        break;
+        return QV4::Value::fromObject(m_v4Engine->newRegExpObject(*reinterpret_cast<const QRegExp *>(data))).asReturnedValue();
     case QMetaType::QObjectStar:
-        result = QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(data));
-        break;
+        return QV4::QObjectWrapper::wrap(m_v4Engine, *reinterpret_cast<QObject* const *>(data));
     case QMetaType::QVariant:
-        result = variantToJS(*reinterpret_cast<const QVariant*>(data));
-        break;
+        return variantToJS(*reinterpret_cast<const QVariant*>(data));
     case QMetaType::QJsonValue:
-        result = QV4::JsonObject::fromJsonValue(m_v4Engine, *reinterpret_cast<const QJsonValue *>(data));
-        break;
+        return QV4::JsonObject::fromJsonValue(m_v4Engine, *reinterpret_cast<const QJsonValue *>(data));
     case QMetaType::QJsonObject:
-        result = QV4::JsonObject::fromJsonObject(m_v4Engine, *reinterpret_cast<const QJsonObject *>(data));
-        break;
+        return QV4::JsonObject::fromJsonObject(m_v4Engine, *reinterpret_cast<const QJsonObject *>(data));
     case QMetaType::QJsonArray:
-        result = QV4::JsonObject::fromJsonArray(m_v4Engine, *reinterpret_cast<const QJsonArray *>(data));
-        break;
+        return QV4::JsonObject::fromJsonArray(m_v4Engine, *reinterpret_cast<const QJsonArray *>(data));
     default:
         if (type == qMetaTypeId<QJSValue>()) {
             return QJSValuePrivate::get(*reinterpret_cast<const QJSValue*>(data))->getValue(m_v4Engine);
         } else {
             QByteArray typeName = QMetaType::typeName(type);
             if (typeName.endsWith('*') && !*reinterpret_cast<void* const *>(data)) {
-                return QV4::Value::nullValue();
+                return QV4::Encode::null();
             } else {
                 // Fall back to wrapping in a QVariant.
-                result = QV4::Value::fromObject(m_v4Engine->newVariantObject(QVariant(type, data)));
+                return QV4::Value::fromObject(m_v4Engine->newVariantObject(QVariant(type, data))).asReturnedValue();
             }
         }
     }
-    return result;
+    Q_UNREACHABLE();
+    return 0;
 }
 
 // Converts a JS value to a meta-type.
@@ -874,7 +867,7 @@ bool QV8Engine::metaTypeFromJS(const QV4::Value &value, int type, void *data) {
 }
 
 // Converts a QVariant to JS.
-QV4::Value QV8Engine::variantToJS(const QVariant &value)
+QV4::ReturnedValue QV8Engine::variantToJS(const QVariant &value)
 {
     return metaTypeToJS(value.userType(), value.constData());
 }
diff --git a/src/qml/qml/v8/qv8engine_p.h b/src/qml/qml/v8/qv8engine_p.h
index 1296973394..3209e55434 100644
--- a/src/qml/qml/v8/qv8engine_p.h
+++ b/src/qml/qml/v8/qv8engine_p.h
@@ -121,6 +121,7 @@ namespace QV4 {
 // valid during the call.  If the return value isn't set within myMethod(), the will return
 // undefined.
 class QV8Engine;
+// ### GC
 class QQmlV4Function
 {
 public:
@@ -129,6 +130,7 @@ public:
     QQmlContextData *context() { return ctx; }
     QV4::Value qmlGlobal() { return global; }
     void setReturnValue(const QV4::Value &rv) { *retVal = rv; }
+    void setReturnValue(QV4::ReturnedValue rv) { *retVal = QV4::Value::fromReturnedValue(rv); }
     QV8Engine *engine() const { return e; }
 private:
     friend struct QV4::QObjectMethod;
@@ -149,6 +151,7 @@ private:
     QV8Engine *e;
 };
 
+// ### GC
 class Q_QML_PRIVATE_EXPORT QQmlV4Handle
 {
 public:
@@ -210,7 +213,7 @@ public:
     void freezeObject(const QV4::Value &value);
 
     QVariant toVariant(const QV4::Value &value, int typeHint);
-    QV4::Value fromVariant(const QVariant &);
+    QV4::ReturnedValue fromVariant(const QVariant &);
 
     // Return a JS string for the given QString \a string
     QV4::Value toString(const QString &string);
@@ -232,19 +235,19 @@ public:
     inline Deletable *extensionData(int) const;
     void setExtensionData(int, Deletable *);
 
-    QV4::Value variantListToJS(const QVariantList &lst);
+    QV4::ReturnedValue variantListToJS(const QVariantList &lst);
     inline QVariantList variantListFromJS(QV4::ArrayObject *array)
     { V8ObjectSet visitedObjects; return variantListFromJS(array, visitedObjects); }
 
-    QV4::Value variantMapToJS(const QVariantMap &vmap);
+    QV4::ReturnedValue variantMapToJS(const QVariantMap &vmap);
     inline QVariantMap variantMapFromJS(QV4::Object *object)
     { V8ObjectSet visitedObjects; return variantMapFromJS(object, visitedObjects); }
 
-    QV4::Value variantToJS(const QVariant &value);
+    QV4::ReturnedValue variantToJS(const QVariant &value);
     inline QVariant variantFromJS(const QV4::Value &value)
     { V8ObjectSet visitedObjects; return variantFromJS(value, visitedObjects); }
 
-    QV4::Value metaTypeToJS(int type, const void *data);
+    QV4::ReturnedValue metaTypeToJS(int type, const void *data);
     bool metaTypeFromJS(const QV4::Value &value, int type, void *data);
 
     bool convertToNativeQObject(const QV4::Value &value,
diff --git a/src/qml/types/qqmldelegatemodel.cpp b/src/qml/types/qqmldelegatemodel.cpp
index 163407c809..0457adb348 100644
--- a/src/qml/types/qqmldelegatemodel.cpp
+++ b/src/qml/types/qqmldelegatemodel.cpp
@@ -63,10 +63,10 @@ struct DelegateModelGroupFunction: QV4::FunctionObject
 {
     Q_MANAGED
 
-    QV4::Value (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg);
+    QV4::ReturnedValue (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg);
     uint flag;
 
-    DelegateModelGroupFunction(QV4::ExecutionContext *scope, uint flag, QV4::Value (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg))
+    DelegateModelGroupFunction(QV4::ExecutionContext *scope, uint flag, QV4::ReturnedValue (*code)(QQmlDelegateModelItem *item, uint flag, const QV4::Value &arg))
         : FunctionObject(scope, /*name*/0)
         , code(code)
         , flag(flag)
@@ -89,7 +89,7 @@ struct DelegateModelGroupFunction: QV4::FunctionObject
             that->engine()->current->throwTypeError(QStringLiteral("Not a valid VisualData object"));
 
         QV4::Value v = callData->argc ? callData->args[0] : QV4::Value::undefinedValue();
-        return f->code(o->item, f->flag, v).asReturnedValue();
+        return f->code(o->item, f->flag, v);
     }
 };
 
@@ -1550,13 +1550,16 @@ bool QQmlDelegateModelPrivate::insert(Compositor::insert_iterator &before, const
     if (!o)
         return false;
 
+    QV4::Scope scope(o->engine());
+
     QV4::ObjectIterator it(o, QV4::ObjectIterator::EnumerableOnly|QV4::ObjectIterator::WithProtoChain);
+    QV4::ScopedValue propertyName(scope);
     while (1) {
         QV4::Value value;
-        QV4::Value propertyName = it.nextPropertyNameAsString(&value);
-        if (propertyName.isNull())
+        propertyName = it.nextPropertyNameAsString(&value);
+        if (propertyName->isNull())
             break;
-        cacheItem->setValue(propertyName.toQStringNoThrow(), m_cacheMetaType->v8Engine->toVariant(value, QVariant::Invalid));
+        cacheItem->setValue(propertyName->toQStringNoThrow(), m_cacheMetaType->v8Engine->toVariant(value, QVariant::Invalid));
     }
 
     cacheItem->groups = groups | Compositor::UnresolvedFlag | Compositor::CacheFlag;
@@ -1698,7 +1701,7 @@ QV4::ReturnedValue QQmlDelegateModelItem::get_model(QV4::SimpleCallContext *ctx)
     if (!o->item->metaType->model)
         return QV4::Encode::undefined();
 
-    return o->item->get().asReturnedValue();
+    return o->item->get();
 }
 
 QV4::ReturnedValue QQmlDelegateModelItem::get_groups(QV4::SimpleCallContext *ctx)
@@ -1713,7 +1716,7 @@ QV4::ReturnedValue QQmlDelegateModelItem::get_groups(QV4::SimpleCallContext *ctx
             groups.append(o->item->metaType->groupNames.at(i - 1));
     }
 
-    return ctx->engine->v8Engine->fromVariant(groups).asReturnedValue();
+    return ctx->engine->v8Engine->fromVariant(groups);
 }
 
 QV4::ReturnedValue QQmlDelegateModelItem::set_groups(QV4::SimpleCallContext *ctx)
@@ -1735,22 +1738,22 @@ QV4::ReturnedValue QQmlDelegateModelItem::set_groups(QV4::SimpleCallContext *ctx
     return QV4::Encode::undefined();
 }
 
-QV4::Value QQmlDelegateModelItem::get_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
+QV4::ReturnedValue QQmlDelegateModelItem::get_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
 {
-    return QV4::Value::fromBoolean(thisItem->groups & (1 << flag));
+    return QV4::Encode(bool(thisItem->groups & (1 << flag)));
 }
 
-QV4::Value QQmlDelegateModelItem::set_member(QQmlDelegateModelItem *cacheItem, uint flag, const QV4::Value &arg)
+QV4::ReturnedValue QQmlDelegateModelItem::set_member(QQmlDelegateModelItem *cacheItem, uint flag, const QV4::Value &arg)
 {
     if (!cacheItem->metaType->model)
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
 
     QQmlDelegateModelPrivate *model = QQmlDelegateModelPrivate::get(cacheItem->metaType->model);
 
     bool member = arg.toBoolean();
     uint groupFlag = (1 << flag);
     if (member == ((cacheItem->groups & groupFlag) != 0))
-        return QV4::Value::undefinedValue();
+        return QV4::Encode::undefined();
 
     const int cacheIndex = model->m_cache.indexOf(cacheItem);
     Compositor::iterator it = model->m_compositor.find(Compositor::Cache, cacheIndex);
@@ -1758,12 +1761,12 @@ QV4::Value QQmlDelegateModelItem::set_member(QQmlDelegateModelItem *cacheItem, u
         model->addGroups(it, 1, Compositor::Cache, groupFlag);
     else
         model->removeGroups(it, 1, Compositor::Cache, groupFlag);
-    return QV4::Value::undefinedValue();
+    return QV4::Encode::undefined();
 }
 
-QV4::Value QQmlDelegateModelItem::get_index(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
+QV4::ReturnedValue QQmlDelegateModelItem::get_index(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &)
 {
-    return QV4::Value::fromInt32(thisItem->groupIndex(Compositor::Group(flag)));
+    return QV4::Encode((int)thisItem->groupIndex(Compositor::Group(flag)));
 }
 
 
diff --git a/src/qml/types/qqmldelegatemodel_p_p.h b/src/qml/types/qqmldelegatemodel_p_p.h
index 9b1b64b8db..aa4e0c30e2 100644
--- a/src/qml/types/qqmldelegatemodel_p_p.h
+++ b/src/qml/types/qqmldelegatemodel_p_p.h
@@ -128,7 +128,7 @@ public:
     int modelIndex() const { return index; }
     void setModelIndex(int idx) { index = idx; Q_EMIT modelIndexChanged(); }
 
-    virtual QV4::Value get() { return QV4::QObjectWrapper::wrap(v4, this); }
+    virtual QV4::ReturnedValue get() { return QV4::QObjectWrapper::wrap(v4, this); }
 
     virtual void setValue(const QString &role, const QVariant &value) { Q_UNUSED(role); Q_UNUSED(value); }
     virtual bool resolveIndex(const QQmlAdaptorModel &, int) { return false; }
@@ -136,9 +136,9 @@ public:
     static QV4::ReturnedValue get_model(QV4::SimpleCallContext *ctx);
     static QV4::ReturnedValue get_groups(QV4::SimpleCallContext *ctx);
     static QV4::ReturnedValue set_groups(QV4::SimpleCallContext *ctx);
-    static QV4::Value get_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &);
-    static QV4::Value set_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &arg);
-    static QV4::Value get_index(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &arg);
+    static QV4::ReturnedValue get_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &);
+    static QV4::ReturnedValue set_member(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &arg);
+    static QV4::ReturnedValue get_index(QQmlDelegateModelItem *thisItem, uint flag, const QV4::Value &arg);
 
     QV4::ExecutionEngine *v4;
     QQmlDelegateModelItemMetaType * const metaType;
diff --git a/src/qml/types/qqmllistmodel.cpp b/src/qml/types/qqmllistmodel.cpp
index 87e907e244..20d1211716 100644
--- a/src/qml/types/qqmllistmodel.cpp
+++ b/src/qml/types/qqmllistmodel.cpp
@@ -418,9 +418,10 @@ void ListModel::set(int elementIndex, QV4::Object *object, QVector<int> *roles,
     QV4::Scoped<QV4::Object> o(scope);
 
     QV4::ObjectIterator it(object, QV4::ObjectIterator::WithProtoChain|QV4::ObjectIterator::EnumerableOnly);
+    QV4::Scoped<QV4::String> propertyName(scope);
     while (1) {
         QV4::Value propertyValue;
-        QV4::String *propertyName = it.nextPropertyNameAsString(&propertyValue).asString();
+        propertyName = it.nextPropertyNameAsString(&propertyValue);
         if (!propertyName)
             break;
 
@@ -429,13 +430,13 @@ void ListModel::set(int elementIndex, QV4::Object *object, QVector<int> *roles,
 
         // Add the value now
         if (QV4::String *s = propertyValue.asString()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::String);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::String);
             roleIndex = e->setStringProperty(r, s->toQString());
         } else if (propertyValue.isNumber()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::Number);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::Number);
             roleIndex = e->setDoubleProperty(r, propertyValue.asDouble());
         } else if (QV4::ArrayObject *a = propertyValue.asArrayObject()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::List);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::List);
             ListModel *subModel = new ListModel(r.subLayout, 0, -1);
 
             int arrayLength = a->arrayLength();
@@ -446,25 +447,25 @@ void ListModel::set(int elementIndex, QV4::Object *object, QVector<int> *roles,
 
             roleIndex = e->setListProperty(r, subModel);
         } else if (propertyValue.isBoolean()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::Bool);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::Bool);
             roleIndex = e->setBoolProperty(r, propertyValue.booleanValue());
         } else if (QV4::DateObject *dd = propertyValue.asDateObject()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::DateTime);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::DateTime);
             QDateTime dt = dd->toQDateTime();
             roleIndex = e->setDateTimeProperty(r, dt);
         } else if (QV4::Object *o = propertyValue.asObject()) {
             if (QV4::QObjectWrapper *wrapper = o->as<QV4::QObjectWrapper>()) {
                 QObject *o = wrapper->object();
-                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::QObject);
+                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::QObject);
                 if (role.type == ListLayout::Role::QObject)
                     roleIndex = e->setQObjectProperty(role, o);
             } else {
-                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::VariantMap);
+                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::VariantMap);
                 if (role.type == ListLayout::Role::VariantMap)
                     roleIndex = e->setVariantMapProperty(role, o, eng);
             }
         } else if (propertyValue.isEmpty() || propertyValue.isUndefined() || propertyValue.isNull()) {
-            const ListLayout::Role *r = m_layout->getExistingRole(propertyName);
+            const ListLayout::Role *r = m_layout->getExistingRole(propertyName.getPointer());
             if (r)
                 e->clearProperty(*r);
         }
@@ -487,24 +488,25 @@ void ListModel::set(int elementIndex, QV4::Object *object, QV8Engine *eng)
     QV4::Scoped<QV4::Object> o(scope);
 
     QV4::ObjectIterator it(object, QV4::ObjectIterator::WithProtoChain|QV4::ObjectIterator::EnumerableOnly);
+    QV4::Scoped<QV4::String> propertyName(scope);
     while (1) {
         QV4::Value propertyValue;
-        QV4::String *propertyName = it.nextPropertyNameAsString(&propertyValue).asString();
+        propertyName = it.nextPropertyNameAsString(&propertyValue);
         if (!propertyName)
             break;
 
         // Add the value now
         if (QV4::String *s = propertyValue.asString()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::String);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::String);
             if (r.type == ListLayout::Role::String)
                 e->setStringPropertyFast(r, s->toQString());
         } else if (propertyValue.isNumber()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::Number);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::Number);
             if (r.type == ListLayout::Role::Number) {
                 e->setDoublePropertyFast(r, propertyValue.asDouble());
             }
         } else if (QV4::ArrayObject *a = propertyValue.asArrayObject()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::List);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::List);
             if (r.type == ListLayout::Role::List) {
                 ListModel *subModel = new ListModel(r.subLayout, 0, -1);
 
@@ -517,12 +519,12 @@ void ListModel::set(int elementIndex, QV4::Object *object, QV8Engine *eng)
                 e->setListPropertyFast(r, subModel);
             }
         } else if (propertyValue.isBoolean()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::Bool);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::Bool);
             if (r.type == ListLayout::Role::Bool) {
                 e->setBoolPropertyFast(r, propertyValue.booleanValue());
             }
         } else if (QV4::DateObject *dd = propertyValue.asDateObject()) {
-            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::DateTime);
+            const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::DateTime);
             if (r.type == ListLayout::Role::DateTime) {
                 QDateTime dt = dd->toQDateTime();;
                 e->setDateTimePropertyFast(r, dt);
@@ -530,16 +532,16 @@ void ListModel::set(int elementIndex, QV4::Object *object, QV8Engine *eng)
         } else if (QV4::Object *o = propertyValue.asObject()) {
             if (QV4::QObjectWrapper *wrapper = o->as<QV4::QObjectWrapper>()) {
                 QObject *o = wrapper->object();
-                const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::QObject);
+                const ListLayout::Role &r = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::QObject);
                 if (r.type == ListLayout::Role::QObject)
                     e->setQObjectPropertyFast(r, o);
             } else {
-                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName, ListLayout::Role::VariantMap);
+                const ListLayout::Role &role = m_layout->getRoleOrCreate(propertyName.getPointer(), ListLayout::Role::VariantMap);
                 if (role.type == ListLayout::Role::VariantMap)
                     e->setVariantMapFast(role, o, eng);
             }
         } else if (propertyValue.isEmpty() || propertyValue.isUndefined() || propertyValue.isNull()) {
-            const ListLayout::Role *r = m_layout->getExistingRole(propertyName);
+            const ListLayout::Role *r = m_layout->getExistingRole(propertyName.getPointer());
             if (r)
                 e->clearProperty(*r);
         }
@@ -1252,7 +1254,8 @@ void ModelNodeMetaObject::propertyWritten(int index)
     QString propName = QString::fromUtf8(name(index));
     QVariant value = operator[](index);
 
-    QV4::Value v = eng->fromVariant(value);
+    QV4::Scope scope(QV8Engine::getV4((eng)));
+    QV4::ScopedValue v(scope, eng->fromVariant(value));
 
     int roleIndex = m_obj->m_model->m_listModel->setExistingProperty(m_obj->m_elementIndex, propName, v, eng);
     if (roleIndex != -1) {
@@ -2103,10 +2106,11 @@ void QQmlListModel::append(QQmlV4Function *args)
 */
 QQmlV4Handle QQmlListModel::get(int index) const
 {
-    QV4::Value result = QV4::Value::undefinedValue();
+    QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine());
+    QV4::Scope scope(v4);
+    QV4::ScopedValue result(scope, QV4::Value::undefinedValue());
 
     if (index >= 0 && index < count()) {
-        QV4::ExecutionEngine *v4 = QV8Engine::getV4(engine());
 
         if (m_dynamicRoles) {
             DynamicRoleModelNode *object = m_modelObjects[index];
diff --git a/src/qml/types/qquickworkerscript.cpp b/src/qml/types/qquickworkerscript.cpp
index 3e4748fa7a..4e39682d84 100644
--- a/src/qml/types/qquickworkerscript.cpp
+++ b/src/qml/types/qquickworkerscript.cpp
@@ -725,7 +725,8 @@ bool QQuickWorkerScript::event(QEvent *event)
         if (engine) {
             WorkerDataEvent *workerEvent = static_cast<WorkerDataEvent *>(event);
             QV8Engine *v8engine = QQmlEnginePrivate::get(engine)->v8engine();
-            QV4::Value value = QV4::Serialize::deserialize(workerEvent->data(), v8engine);
+            QV4::Scope scope(QV8Engine::getV4(v8engine));
+            QV4::ScopedValue value(scope, QV4::Serialize::deserialize(workerEvent->data(), v8engine));
             emit message(QQmlV4Handle(value));
         }
         return true;
diff --git a/src/qml/util/qqmladaptormodel.cpp b/src/qml/util/qqmladaptormodel.cpp
index b64a393bd3..9812e2a4a6 100644
--- a/src/qml/util/qqmladaptormodel.cpp
+++ b/src/qml/util/qqmladaptormodel.cpp
@@ -107,8 +107,8 @@ public:
     void setValue(const QString &role, const QVariant &value);
     bool resolveIndex(const QQmlAdaptorModel &model, int idx);
 
-    static QV4::Value get_property(QV4::SimpleCallContext *ctx, uint propertyId);
-    static QV4::Value set_property(QV4::SimpleCallContext *ctx, uint propertyId);
+    static QV4::ReturnedValue get_property(QV4::SimpleCallContext *ctx, uint propertyId);
+    static QV4::ReturnedValue set_property(QV4::SimpleCallContext *ctx, uint propertyId);
 
     VDMModelDelegateDataType *type;
     QVector<QVariant> cachedData;
@@ -341,7 +341,7 @@ bool QQmlDMCachedModelData::resolveIndex(const QQmlAdaptorModel &, int idx)
     }
 }
 
-QV4::Value QQmlDMCachedModelData::get_property(QV4::SimpleCallContext *ctx, uint propertyId)
+QV4::ReturnedValue QQmlDMCachedModelData::get_property(QV4::SimpleCallContext *ctx, uint propertyId)
 {
     QQmlDelegateModelItemObject *o = ctx->thisObject.as<QQmlDelegateModelItemObject>();
     if (!o)
@@ -357,10 +357,10 @@ QV4::Value QQmlDMCachedModelData::get_property(QV4::SimpleCallContext *ctx, uint
         return ctx->engine->v8Engine->fromVariant(
                 modelData->value(modelData->type->propertyRoles.at(propertyId)));
     }
-    return QV4::Value::undefinedValue();
+    return QV4::Encode::undefined();
 }
 
-QV4::Value QQmlDMCachedModelData::set_property(QV4::SimpleCallContext *ctx, uint propertyId)
+QV4::ReturnedValue QQmlDMCachedModelData::set_property(QV4::SimpleCallContext *ctx, uint propertyId)
 {
     QQmlDelegateModelItemObject *o = ctx->thisObject.as<QQmlDelegateModelItemObject>();
     if (!o)
@@ -381,6 +381,7 @@ QV4::Value QQmlDMCachedModelData::set_property(QV4::SimpleCallContext *ctx, uint
             }
         }
     }
+    return QV4::Encode::undefined();
 }
 
 //-----------------------------------------------------------------
@@ -421,7 +422,7 @@ public:
                 type->model->aim()->index(index, 0, type->model->rootIndex), value, role);
     }
 
-    QV4::Value get()
+    QV4::ReturnedValue get()
     {
         if (type->prototype.isEmpty()) {
             QQmlAdaptorModelEngineData * const data = engineData(v4->v8Engine);
@@ -432,7 +433,7 @@ public:
         o->setPrototype(proto);
         QV4::Value data = QV4::Value::fromObject(o);
         ++scriptRef;
-        return data;
+        return data.asReturnedValue();
     }
 };
 
@@ -584,7 +585,7 @@ public:
         if (!o)
             ctx->throwTypeError(QStringLiteral("Not a valid VisualData object"));
 
-        return ctx->engine->v8Engine->fromVariant(static_cast<QQmlDMListAccessorData *>(o->item)->cachedData).asReturnedValue();
+        return ctx->engine->v8Engine->fromVariant(static_cast<QQmlDMListAccessorData *>(o->item)->cachedData);
     }
 
     static QV4::ReturnedValue set_modelData(QV4::SimpleCallContext *ctx)
@@ -599,14 +600,14 @@ public:
         return QV4::Encode::undefined();
     }
 
-    QV4::Value get()
+    QV4::ReturnedValue get()
     {
         QQmlAdaptorModelEngineData *data = engineData(v4->v8Engine);
         QV4::Object *o = new (v4->memoryManager) QQmlDelegateModelItemObject(v4, this);
         o->setPrototype(data->listItemProto.value().asObject());
         QV4::Value val = QV4::Value::fromObject(o);
         ++scriptRef;
-        return val;
+        return val.asReturnedValue();
     }
 
     void setValue(const QString &role, const QVariant &value)
diff --git a/src/quick/items/context2d/qquickcanvasitem.cpp b/src/quick/items/context2d/qquickcanvasitem.cpp
index 054dac5afd..bf1cff460d 100644
--- a/src/quick/items/context2d/qquickcanvasitem.cpp
+++ b/src/quick/items/context2d/qquickcanvasitem.cpp
@@ -663,7 +663,7 @@ void QQuickCanvasItem::updatePolish()
         QV4::ExecutionEngine *v4 = QQmlEnginePrivate::getV4Engine(qmlEngine(this));
         QV4::Scope scope(v4);
         QV4::ScopedCallData callData(scope, 1);
-        callData->thisObject = QV4::QObjectWrapper::wrap(v4, this);
+        callData->thisObject = QV4::Value::fromReturnedValue(QV4::QObjectWrapper::wrap(v4, this));
 
         foreach (int key, animationCallbacks.keys()) {
             QV4::FunctionObject *f = animationCallbacks.value(key).value().asFunctionObject();
diff --git a/src/quick/items/context2d/qquickcontext2d.cpp b/src/quick/items/context2d/qquickcontext2d.cpp
index f3a3f28ccb..bc8e49797d 100644
--- a/src/quick/items/context2d/qquickcontext2d.cpp
+++ b/src/quick/items/context2d/qquickcontext2d.cpp
@@ -944,7 +944,7 @@ QV4::ReturnedValue QQuickJSContext2DPrototype::method_get_canvas(QV4::SimpleCall
     QQuickJSContext2D *r = ctx->thisObject.as<QQuickJSContext2D>();
     CHECK_CONTEXT(r)
 
-    return QV4::QObjectWrapper::wrap(ctx->engine, r->context->canvas()).asReturnedValue();
+    return QV4::QObjectWrapper::wrap(ctx->engine, r->context->canvas());
 }
 
 /*!
@@ -1386,7 +1386,7 @@ QV4::ReturnedValue QQuickJSContext2D::method_get_fillRule(QV4::SimpleCallContext
     CHECK_CONTEXT(r)
 
     QV8Engine *engine = ctx->engine->v8Engine;
-    return engine->fromVariant(r->context->state.fillRule).asReturnedValue();
+    return engine->fromVariant(r->context->state.fillRule);
 }
 
 QV4::ReturnedValue QQuickJSContext2D::method_set_fillRule(QV4::SimpleCallContext *ctx)
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 24478417d5..086ffbae64 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -2268,12 +2268,12 @@ static inline bool evaluate_error(QV8Engine *engine, const QV4::Value &o, const
     program.inheritContext = true;
 
     QV4::ExecutionContext *ctx = QV8Engine::getV4(engine)->current;
+    QV4::Scope scope(ctx);
 
     try {
-        QV4::FunctionObject *function = program.run().asFunctionObject();
+        QV4::Scoped<QV4::FunctionObject> function(scope, program.run());
         if (!function)
             return false;
-        QV4::Scope scope(ctx);
         QV4::ScopedCallData d(scope, 1);
         d->args[0] = o;
         d->thisObject = engine->global();
@@ -2295,11 +2295,13 @@ static inline bool evaluate_value(QV8Engine *engine, const QV4::Value &o,
     program.inheritContext = true;
 
     QV4::ExecutionContext *ctx = QV8Engine::getV4(engine)->current;
+    QV4::Scope scope(ctx);
+
     try {
-        QV4::FunctionObject *function = program.run().asFunctionObject();
+        QV4::Scoped<QV4::FunctionObject> function(scope, program.run());
         if (!function)
             return false;
-        QV4::Scope scope(ctx);
+
         QV4::ScopedValue value(scope);
         QV4::ScopedValue res(scope, result);
         QV4::ScopedCallData d(scope, 1);
@@ -2320,13 +2322,14 @@ static inline QV4::Value evaluate(QV8Engine *engine, const QV4::Value & o,
                              QLatin1String(source) + QLatin1String(" })");
 
     QV4::ExecutionContext *ctx = QV8Engine::getV4(engine)->current;
+    QV4::Scope scope(ctx);
+
     QV4::Script program(QV8Engine::getV4(engine)->rootContext, functionSource);
     program.inheritContext = true;
     try {
-        QV4::FunctionObject *function = program.run().asFunctionObject();
+        QV4::Scoped<QV4::FunctionObject> function(scope, program.run());
         if (!function)
             return QV4::Value::emptyValue();
-        QV4::Scope scope(ctx);
         QV4::ScopedCallData d(scope, 1);
         d->args[0] = o;
         d->thisObject = engine->global();
@@ -2352,8 +2355,9 @@ void tst_qqmlecmascript::callQtInvokables()
     QQmlEnginePrivate *ep = QQmlEnginePrivate::get(&qmlengine);
     
     QV8Engine *engine = ep->v8engine();
+    QV4::Scope scope(QV8Engine::getV4(engine));
 
-    QV4::Value object = QV4::QObjectWrapper::wrap(QV8Engine::getV4(engine), o);
+    QV4::ScopedValue object(scope, QV4::QObjectWrapper::wrap(QV8Engine::getV4(engine), o));
 
     // Non-existent methods
     o->reset();
@@ -3899,7 +3903,8 @@ void tst_qqmlecmascript::verifyContextLifetime(QQmlContextData *ctxt) {
             scriptContext = QV4::QmlContextWrapper::getContext(qmlglobal);
 
             {
-                QV4::Value temporaryScope = QV4::QmlContextWrapper::qmlScope(engine, scriptContext, 0);
+                QV4::Scope scope(QV8Engine::getV4((engine)));
+                QV4::ScopedValue temporaryScope(scope, QV4::QmlContextWrapper::qmlScope(engine, scriptContext, 0));
                 Q_UNUSED(temporaryScope)
             }
 
@@ -4981,9 +4986,9 @@ void tst_qqmlecmascript::propertyVarInheritance()
     {
         // XXX NOTE: this is very implementation dependent.  QDVMEMO->vmeProperty() is the only
         // public function which can return us a handle to something in the varProperties array.
-        QV4::Value tmp = icovmemo->vmeProperty(ico5->metaObject()->indexOfProperty("circ"));
+        QV4::Value tmp = QV4::Value::fromReturnedValue(icovmemo->vmeProperty(ico5->metaObject()->indexOfProperty("circ")));
         icoCanaryHandle = tmp;
-        tmp = ccovmemo->vmeProperty(cco5->metaObject()->indexOfProperty("circ"));
+        tmp = QV4::Value::fromReturnedValue(ccovmemo->vmeProperty(cco5->metaObject()->indexOfProperty("circ")));
         ccoCanaryHandle = tmp;
         tmp = QV4::Value::nullValue();
         QVERIFY(!icoCanaryHandle.isEmpty());
@@ -5027,7 +5032,7 @@ void tst_qqmlecmascript::propertyVarInheritance2()
     QCOMPARE(childObject->property("textCanary").toInt(), 10);
     QV4::WeakValue childObjectVarArrayValueHandle;
     {
-        QV4::Value tmp = QQmlVMEMetaObject::get(childObject)->vmeProperty(childObject->metaObject()->indexOfProperty("vp"));
+        QV4::Value tmp = QV4::Value::fromReturnedValue(QQmlVMEMetaObject::get(childObject)->vmeProperty(childObject->metaObject()->indexOfProperty("vp")));
         childObjectVarArrayValueHandle = tmp;
         tmp = QV4::Value::nullValue();
         QVERIFY(!childObjectVarArrayValueHandle.isEmpty());