Always set the correct FunctionObject when calling JS functions

Renamed ScopedCallData to JSCall, enforced passing a JS
FunctionObject to it, and added call() and callAsConstructor()
methods to it.

Change-Id: I30db65c9765c2896b5909fe2105c0934c6dad861
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

30 files changed, 308 insertions, 303 deletions

diff --git a/src/imports/localstorage/plugin.cpp b/src/imports/localstorage/plugin.cpp
index 5f3cfc43c4..795103cd26 100644
--- a/src/imports/localstorage/plugin.cpp
+++ b/src/imports/localstorage/plugin.cpp
@@ -414,12 +414,12 @@ static ReturnedValue qmlsqldatabase_changeVersion(const QV4::BuiltinFunction *b,
         ok = false;
         db.transaction();
 
-        ScopedCallData callData(scope, 1);
-        callData->thisObject = scope.engine->globalObject;
-        callData->args[0] = w;
+        JSCall jsCall(scope, callback, 1);
+        jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = w;
 
         TransactionRollback rollbackOnException(&db, &w->d()->inTransaction);
-        callback->call(callData);
+        jsCall.call();
         rollbackOnException.clear();
         if (!db.commit()) {
             db.rollback();
@@ -464,11 +464,11 @@ static ReturnedValue qmlsqldatabase_transaction_shared(const QV4::BuiltinFunctio
 
     db.transaction();
     if (callback) {
-        ScopedCallData callData(scope, 1);
-        callData->thisObject = scope.engine->globalObject;
-        callData->args[0] = w;
+        JSCall jsCall(scope, callback, 1);
+        jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = w;
         TransactionRollback rollbackOnException(&db, &w->d()->inTransaction);
-        callback->call(callData);
+        jsCall.call();
         rollbackOnException.clear();
 
         if (!db.commit())
@@ -763,10 +763,10 @@ void QQuickLocalStorage::openDatabaseSync(QQmlV4Function *args)
     *db->d()->version = version;
 
     if (created && dbcreationCallback) {
-        ScopedCallData callData(scope, 1);
-        callData->thisObject = scope.engine->globalObject;
-        callData->args[0] = db;
-        dbcreationCallback->call(callData);
+        JSCall jsCall(scope, dbcreationCallback, 1);
+        jsCall->thisObject = scope.engine->globalObject;
+        jsCall->args[0] = db;
+        jsCall.call();
     }
 
     args->setReturnValue(db.asReturnedValue());
diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index 3e2d0ccef0..afd2b1560f 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -657,17 +657,17 @@ QJSValue QJSValue::call(const QJSValueList &args)
     Q_ASSERT(engine);
 
     Scope scope(engine);
-    ScopedCallData callData(scope, f, args.length());
-    callData->thisObject = engine->globalObject;
+    JSCall jsCall(scope, f, args.length());
+    jsCall->thisObject = engine->globalObject;
     for (int i = 0; i < args.size(); ++i) {
         if (!QJSValuePrivate::checkEngine(engine, args.at(i))) {
             qWarning("QJSValue::call() failed: cannot call function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
+        jsCall->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
     }
 
-    ScopedValue result(scope, callData.call());
+    ScopedValue result(scope, jsCall.call());
     if (engine->hasException)
         result = engine->catchException();
 
@@ -713,17 +713,17 @@ QJSValue QJSValue::callWithInstance(const QJSValue &instance, const QJSValueList
         return QJSValue();
     }
 
-    ScopedCallData callData(scope, args.size());
-    callData->thisObject = QJSValuePrivate::convertedToValue(engine, instance);
+    JSCall jsCall(scope, f, args.size());
+    jsCall->thisObject = QJSValuePrivate::convertedToValue(engine, instance);
     for (int i = 0; i < args.size(); ++i) {
         if (!QJSValuePrivate::checkEngine(engine, args.at(i))) {
             qWarning("QJSValue::call() failed: cannot call function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
+        jsCall->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
     }
 
-    ScopedValue result(scope, f->call(callData));
+    ScopedValue result(scope, jsCall.call());
     if (engine->hasException)
         result = engine->catchException();
 
@@ -762,16 +762,16 @@ QJSValue QJSValue::callAsConstructor(const QJSValueList &args)
     Q_ASSERT(engine);
 
     Scope scope(engine);
-    ScopedCallData callData(scope, args.size());
+    JSCall jsCall(scope, f, args.size());
     for (int i = 0; i < args.size(); ++i) {
         if (!QJSValuePrivate::checkEngine(engine, args.at(i))) {
             qWarning("QJSValue::callAsConstructor() failed: cannot construct function with argument created in a different engine");
             return QJSValue();
         }
-        callData->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
+        jsCall->args[i] = QJSValuePrivate::convertedToValue(engine, args.at(i));
     }
 
-    ScopedValue result(scope, f->construct(callData));
+    ScopedValue result(scope, jsCall.callAsConstructor());
     if (engine->hasException)
         result = engine->catchException();
 
diff --git a/src/qml/jsruntime/qv4argumentsobject.cpp b/src/qml/jsruntime/qv4argumentsobject.cpp
index b90a186551..1a60725d27 100644
--- a/src/qml/jsruntime/qv4argumentsobject.cpp
+++ b/src/qml/jsruntime/qv4argumentsobject.cpp
@@ -139,10 +139,10 @@ bool ArgumentsObject::defineOwnProperty(ExecutionEngine *engine, uint index, con
     if (isMapped && attrs.isData()) {
         Q_ASSERT(arrayData());
         ScopedFunctionObject setter(scope, map->setter());
-        ScopedCallData callData(scope, setter, 1);
-        callData->thisObject = this->asReturnedValue();
-        callData->args[0] = desc->value;
-        callData.call();
+        JSCall jsCall(scope, setter, 1);
+        jsCall->thisObject = this->asReturnedValue();
+        jsCall->args[0] = desc->value;
+        jsCall.call();
 
         if (attrs.isWritable()) {
             setArrayAttributes(index, mapAttrs);
diff --git a/src/qml/jsruntime/qv4arraybuffer.cpp b/src/qml/jsruntime/qv4arraybuffer.cpp
index 33ef7fa6df..bd47d0bc77 100644
--- a/src/qml/jsruntime/qv4arraybuffer.cpp
+++ b/src/qml/jsruntime/qv4arraybuffer.cpp
@@ -187,10 +187,10 @@ ReturnedValue ArrayBufferPrototype::method_slice(const BuiltinFunction *b, CallD
     if (!constructor)
         return v4->throwTypeError();
 
-    ScopedCallData cData(scope, 1);
+    JSCall jsCall(scope, constructor, 1);
     double newLen = qMax(final - first, 0.);
-    cData->args[0] = QV4::Encode(newLen);
-    QV4::Scoped<ArrayBuffer> newBuffer(scope, constructor->construct(cData));
+    jsCall->args[0] = QV4::Encode(newLen);
+    QV4::Scoped<ArrayBuffer> newBuffer(scope, jsCall.callAsConstructor());
     if (!newBuffer || newBuffer->d()->data->size < (int)newLen)
         return v4->throwTypeError();
 
diff --git a/src/qml/jsruntime/qv4arraydata.cpp b/src/qml/jsruntime/qv4arraydata.cpp
index fe9736ea9b..55b6370b42 100644
--- a/src/qml/jsruntime/qv4arraydata.cpp
+++ b/src/qml/jsruntime/qv4arraydata.cpp
@@ -673,15 +673,14 @@ bool ArrayElementLessThan::operator()(Value v1, Value v2) const
         return false;
     if (v2.isUndefined() || v2.isEmpty())
         return true;
-    ScopedObject o(scope, m_comparefn);
+    ScopedFunctionObject o(scope, m_comparefn);
     if (o) {
         Scope scope(o->engine());
         ScopedValue result(scope);
-        ScopedCallData callData(scope, 2);
-        callData->thisObject = Primitive::undefinedValue();
-        callData->args[0] = v1;
-        callData->args[1] = v2;
-        result = QV4::Runtime::method_callValue(scope.engine, m_comparefn, callData);
+        JSCall jsCall(scope, o, 2);
+        jsCall->args[0] = v1;
+        jsCall->args[1] = v2;
+        result = jsCall.call();
 
         return result->toNumber() < 0;
     }
@@ -755,7 +754,7 @@ void ArrayData::sort(ExecutionEngine *engine, Object *thisObject, const Value &c
     if (!arrayData || !arrayData->length())
         return;
 
-    if (!(comparefn.isUndefined() || comparefn.as<Object>())) {
+    if (!comparefn.isUndefined() && !comparefn.isFunctionObject()) {
         engine->throwTypeError();
         return;
     }
@@ -834,7 +833,7 @@ void ArrayData::sort(ExecutionEngine *engine, Object *thisObject, const Value &c
     }
 
 
-    ArrayElementLessThan lessThan(engine, thisObject, comparefn);
+    ArrayElementLessThan lessThan(engine, thisObject, static_cast<const FunctionObject &>(comparefn));
 
     Value *begin = thisObject->arrayData()->values.values;
     sortHelper(begin, begin + len, *begin, lessThan);
diff --git a/src/qml/jsruntime/qv4arrayobject.cpp b/src/qml/jsruntime/qv4arrayobject.cpp
index f7486471ee..7796da5c70 100644
--- a/src/qml/jsruntime/qv4arrayobject.cpp
+++ b/src/qml/jsruntime/qv4arrayobject.cpp
@@ -126,16 +126,17 @@ ReturnedValue ArrayPrototype::method_isArray(const BuiltinFunction *, CallData *
 
 ReturnedValue ArrayPrototype::method_toString(const BuiltinFunction *builtin, CallData *callData)
 {
-    Scope scope(builtin);
-    ScopedObject o(scope, callData->thisObject, ScopedObject::Convert);
-    CHECK_EXCEPTION();
-    ScopedString s(scope, scope.engine->newString(QStringLiteral("join")));
-    ScopedFunctionObject f(scope, o->get(s));
-    if (!!f) {
-        ScopedCallData d(scope, 0);
-        d->thisObject = callData->thisObject;
-        return f->call(d);
+    ExecutionEngine *v4 = builtin->engine();
+    if (!callData->thisObject.isObject()) {
+        callData->thisObject = callData->thisObject.toObject(v4);
+        if (v4->hasException)
+            return QV4::Encode::undefined();
     }
+
+    callData->accumulator = v4->newString(QStringLiteral("join"));
+    callData->function = static_cast<Object &>(callData->thisObject).get(static_cast<String *>(&callData->accumulator));
+    if (callData->function.isFunctionObject())
+        return static_cast<FunctionObject &>(callData->function).call(callData);
     return ObjectPrototype::method_toString(builtin, callData);
 }
 
@@ -197,8 +198,8 @@ ReturnedValue ArrayPrototype::method_find(const BuiltinFunction *b, CallData *ca
     if (!callback)
         THROW_TYPE_ERROR();
 
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
 
     ScopedValue v(scope);
     ScopedValue result(scope);
@@ -207,10 +208,10 @@ ReturnedValue ArrayPrototype::method_find(const BuiltinFunction *b, CallData *ca
         v = instance->getIndexed(k);
         CHECK_EXCEPTION();
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        result = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        result = jsCall.call();
 
         CHECK_EXCEPTION();
         if (result->toBoolean())
@@ -233,8 +234,8 @@ ReturnedValue ArrayPrototype::method_findIndex(const BuiltinFunction *b, CallDat
     if (!callback)
         THROW_TYPE_ERROR();
 
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
 
     ScopedValue v(scope);
     ScopedValue result(scope);
@@ -243,10 +244,10 @@ ReturnedValue ArrayPrototype::method_findIndex(const BuiltinFunction *b, CallDat
         v = instance->getIndexed(k);
         CHECK_EXCEPTION();
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        result = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        result = jsCall.call();
 
         CHECK_EXCEPTION();
         if (result->toBoolean())
@@ -789,8 +790,8 @@ ReturnedValue ArrayPrototype::method_every(const BuiltinFunction *b, CallData *c
     if (!callback)
         THROW_TYPE_ERROR();
 
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
     ScopedValue r(scope);
     ScopedValue v(scope);
 
@@ -801,10 +802,10 @@ ReturnedValue ArrayPrototype::method_every(const BuiltinFunction *b, CallData *c
         if (!exists)
             continue;
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        r = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        r = jsCall.call();
         ok = r->toBoolean();
     }
     return Encode(ok);
@@ -823,8 +824,8 @@ ReturnedValue ArrayPrototype::method_some(const BuiltinFunction *b, CallData *ca
     if (!callback)
         THROW_TYPE_ERROR();
 
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
     ScopedValue v(scope);
     ScopedValue result(scope);
 
@@ -834,10 +835,10 @@ ReturnedValue ArrayPrototype::method_some(const BuiltinFunction *b, CallData *ca
         if (!exists)
             continue;
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        result = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        result = jsCall.call();
         if (result->toBoolean())
             return Encode(true);
     }
@@ -857,8 +858,8 @@ ReturnedValue ArrayPrototype::method_forEach(const BuiltinFunction *b, CallData
     if (!callback)
         THROW_TYPE_ERROR();
 
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
 
     ScopedValue v(scope);
     for (uint k = 0; k < len; ++k) {
@@ -867,10 +868,10 @@ ReturnedValue ArrayPrototype::method_forEach(const BuiltinFunction *b, CallData
         if (!exists)
             continue;
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        jsCall.call();
     }
     RETURN_UNDEFINED();
 }
@@ -893,8 +894,8 @@ ReturnedValue ArrayPrototype::method_map(const BuiltinFunction *b, CallData *cal
     a->setArrayLengthUnchecked(len);
 
     ScopedValue mapped(scope);
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
 
     ScopedValue v(scope);
     for (uint k = 0; k < len; ++k) {
@@ -903,10 +904,10 @@ ReturnedValue ArrayPrototype::method_map(const BuiltinFunction *b, CallData *cal
         if (!exists)
             continue;
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        mapped = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        mapped = jsCall.call();
         a->arraySet(k, mapped);
     }
     return a.asReturnedValue();
@@ -930,8 +931,8 @@ ReturnedValue ArrayPrototype::method_filter(const BuiltinFunction *b, CallData *
 
     ScopedValue selected(scope);
     ScopedValue v(scope);
-    ScopedCallData cData(scope, 3);
-    cData->thisObject = callData->argument(1);
+    JSCall jsCall(scope, callback, 3);
+    jsCall->thisObject = callData->argument(1);
 
     uint to = 0;
     for (uint k = 0; k < len; ++k) {
@@ -940,10 +941,10 @@ ReturnedValue ArrayPrototype::method_filter(const BuiltinFunction *b, CallData *
         if (!exists)
             continue;
 
-        cData->args[0] = v;
-        cData->args[1] = Primitive::fromDouble(k);
-        cData->args[2] = instance;
-        selected = callback->call(cData);
+        jsCall->args[0] = v;
+        jsCall->args[1] = Primitive::fromDouble(k);
+        jsCall->args[2] = instance;
+        selected = jsCall.call();
         if (selected->toBoolean()) {
             a->arraySet(to, v);
             ++to;
@@ -983,18 +984,17 @@ ReturnedValue ArrayPrototype::method_reduce(const BuiltinFunction *b, CallData *
             THROW_TYPE_ERROR();
     }
 
-    ScopedCallData cData(scope, 4);
-    cData->thisObject = Primitive::undefinedValue();
+    JSCall jsCall(scope, callback, 4);
 
     while (k < len) {
         bool kPresent;
         v = instance->getIndexed(k, &kPresent);
         if (kPresent) {
-            cData->args[0] = acc;
-            cData->args[1] = v;
-            cData->args[2] = Primitive::fromDouble(k);
-            cData->args[3] = instance;
-            acc = callback->call(cData);
+            jsCall->args[0] = acc;
+            jsCall->args[1] = v;
+            jsCall->args[2] = Primitive::fromDouble(k);
+            jsCall->args[3] = instance;
+            acc = jsCall.call();
         }
         ++k;
     }
@@ -1037,18 +1037,18 @@ ReturnedValue ArrayPrototype::method_reduceRight(const BuiltinFunction *b, CallD
             THROW_TYPE_ERROR();
     }
 
-    ScopedCallData cData(scope, 4);
-    cData->thisObject = Primitive::undefinedValue();
+    JSCall jsCall(scope, callback, 4);
+    jsCall->thisObject = Primitive::undefinedValue();
 
     while (k > 0) {
         bool kPresent;
         v = instance->getIndexed(k - 1, &kPresent);
         if (kPresent) {
-            cData->args[0] = acc;
-            cData->args[1] = v;
-            cData->args[2] = Primitive::fromDouble(k - 1);
-            cData->args[3] = instance;
-            acc = callback->call(cData);
+            jsCall->args[0] = acc;
+            jsCall->args[1] = v;
+            jsCall->args[2] = Primitive::fromDouble(k - 1);
+            jsCall->args[3] = instance;
+            acc = jsCall.call();
         }
         --k;
     }
diff --git a/src/qml/jsruntime/qv4dateobject.cpp b/src/qml/jsruntime/qv4dateobject.cpp
index 5ac2a43b19..64aecfe352 100644
--- a/src/qml/jsruntime/qv4dateobject.cpp
+++ b/src/qml/jsruntime/qv4dateobject.cpp
@@ -1451,9 +1451,9 @@ ReturnedValue DatePrototype::method_toJSON(const BuiltinFunction *b, CallData *c
     if (!toIso)
         return v4->throwTypeError();
 
-    ScopedCallData cData(scope);
-    cData->thisObject = callData->thisObject;
-    return toIso->call(cData);
+    JSCall jsCall(scope, toIso);
+    jsCall->thisObject = callData->thisObject;
+    return jsCall.call();
 }
 
 void DatePrototype::timezoneUpdated()
diff --git a/src/qml/jsruntime/qv4functionobject.cpp b/src/qml/jsruntime/qv4functionobject.cpp
index 4a6890c651..3f971fcca5 100644
--- a/src/qml/jsruntime/qv4functionobject.cpp
+++ b/src/qml/jsruntime/qv4functionobject.cpp
@@ -286,49 +286,48 @@ ReturnedValue FunctionPrototype::method_apply(const BuiltinFunction *b, CallData
         len = arr->getLength();
     }
 
-    ScopedCallData cData(scope, len);
+    JSCall jsCall(scope, o, len);
 
     if (len) {
         if (ArgumentsObject::isNonStrictArgumentsObject(arr) && !arr->cast<ArgumentsObject>()->fullyCreated()) {
             QV4::ArgumentsObject *a = arr->cast<ArgumentsObject>();
             int l = qMin(len, (uint)a->d()->context->argc());
-            memcpy(cData->args, a->d()->context->args(), l*sizeof(Value));
+            memcpy(jsCall->args, a->d()->context->args(), l*sizeof(Value));
             for (quint32 i = l; i < len; ++i)
-                cData->args[i] = Primitive::undefinedValue();
+                jsCall->args[i] = Primitive::undefinedValue();
         } else if (arr->arrayType() == Heap::ArrayData::Simple && !arr->protoHasArray()) {
             auto sad = static_cast<Heap::SimpleArrayData *>(arr->arrayData());
             uint alen = sad ? sad->values.size : 0;
             if (alen > len)
                 alen = len;
             for (uint i = 0; i < alen; ++i)
-                cData->args[i] = sad->data(i);
+                jsCall->args[i] = sad->data(i);
             for (quint32 i = alen; i < len; ++i)
-                cData->args[i] = Primitive::undefinedValue();
+                jsCall->args[i] = Primitive::undefinedValue();
         } else {
             for (quint32 i = 0; i < len; ++i)
-                cData->args[i] = arr->getIndexed(i);
+                jsCall->args[i] = arr->getIndexed(i);
         }
     }
 
-    cData->thisObject = callData->argument(0);
-    return o->call(cData);
+    jsCall->thisObject = callData->argument(0);
+    return jsCall.call();
 }
 
 ReturnedValue FunctionPrototype::method_call(const BuiltinFunction *b, CallData *callData)
 {
-    QV4::Scope scope(b);
-    FunctionObject *o = callData->thisObject.as<FunctionObject>();
-    if (!o)
-        return scope.engine->throwTypeError();
-
-    ScopedCallData cData(scope, callData->argc ? callData->argc - 1 : 0);
+    if (!callData->thisObject.isFunctionObject()) {
+        ExecutionEngine *e = b->engine();
+        return e->throwTypeError();
+    }
+    callData->function = callData->thisObject;
+    callData->thisObject = callData->argc ? callData->args[0] : Primitive::undefinedValue();
     if (callData->argc) {
-        for (int i = 1; i < callData->argc; ++i)
-            cData->args[i - 1] = callData->args[i];
+        --callData->argc;
+        for (int i = 0; i < callData->argc; ++i)
+            callData->args[i] = callData->args[i + 1];
     }
-    cData->thisObject = callData->argument(0);
-
-    return o->call(cData);
+    return static_cast<FunctionObject &>(callData->function).call(callData);
 }
 
 ReturnedValue FunctionPrototype::method_bind(const BuiltinFunction *b, CallData *callData)
@@ -488,16 +487,15 @@ ReturnedValue BoundFunction::call(const Managed *that, CallData *dd)
         return Encode::undefined();
 
     Scoped<MemberData> boundArgs(scope, f->boundArgs());
-    ScopedCallData callData(scope, (boundArgs ? boundArgs->size() : 0) + dd->argc);
-    callData->thisObject = f->boundThis();
-    Value *argp = callData->args;
+    JSCall jsCall(scope, f->target(), (boundArgs ? boundArgs->size() : 0) + dd->argc);
+    jsCall->thisObject = f->boundThis();
+    Value *argp = jsCall->args;
     if (boundArgs) {
         memcpy(argp, boundArgs->data(), boundArgs->size()*sizeof(Value));
         argp += boundArgs->size();
     }
     memcpy(argp, dd->args, dd->argc*sizeof(Value));
-    ScopedFunctionObject t(scope, f->target());
-    return t->call(callData);
+    return jsCall.call();
 }
 
 ReturnedValue BoundFunction::construct(const Managed *that, CallData *dd)
@@ -509,13 +507,12 @@ ReturnedValue BoundFunction::construct(const Managed *that, CallData *dd)
         return Encode::undefined();
 
     Scoped<MemberData> boundArgs(scope, f->boundArgs());
-    ScopedCallData callData(scope, (boundArgs ? boundArgs->size() : 0) + dd->argc);
-    Value *argp = callData->args;
+    JSCall jsCall(scope, f->target(), (boundArgs ? boundArgs->size() : 0) + dd->argc);
+    Value *argp = jsCall->args;
     if (boundArgs) {
         memcpy(argp, boundArgs->data(), boundArgs->size()*sizeof(Value));
         argp += boundArgs->size();
     }
     memcpy(argp, dd->args, dd->argc*sizeof(Value));
-    ScopedFunctionObject t(scope, f->target());
-    return t->construct(callData);
+    return jsCall.callAsConstructor();
 }
diff --git a/src/qml/jsruntime/qv4globalobject.cpp b/src/qml/jsruntime/qv4globalobject.cpp
index 74173f6a6a..11105dfdcb 100644
--- a/src/qml/jsruntime/qv4globalobject.cpp
+++ b/src/qml/jsruntime/qv4globalobject.cpp
@@ -374,12 +374,12 @@ ReturnedValue EvalFunction::evalCall(CallData *callData, bool directCall) const
 
     if (function->isStrict() || (ctx->d()->v4Function->isStrict())) {
         ScopedFunctionObject e(scope, FunctionObject::createScriptFunction(ctx, function));
-        ScopedCallData callData(scope, 0);
+        JSCall jsCall(scope, e, 0);
         if (directCall)
-            callData->thisObject = scope.engine->currentStackFrame->thisObject();
+            jsCall->thisObject = scope.engine->currentStackFrame->thisObject();
         else
-            callData->thisObject = scope.engine->globalObject;
-        return e->call(callData);
+            jsCall->thisObject = scope.engine->globalObject;
+        return jsCall.call();
     }
 
     ContextStateSaver stateSaver(scope, ctx);
@@ -387,10 +387,10 @@ ReturnedValue EvalFunction::evalCall(CallData *callData, bool directCall) const
     // set the correct v4 function for the context
     ctx->d()->v4Function = function;
 
-    ScopedCallData cData(scope);
-    cData->thisObject = scope.engine->currentStackFrame->thisObject();
-    cData->context = *ctx;
-    return function->call(cData);
+    JSCall jsCall(scope, nullptr);
+    jsCall->thisObject = scope.engine->currentStackFrame->thisObject();
+    jsCall->context = *ctx;
+    return function->call(jsCall);
 }
 
 
diff --git a/src/qml/jsruntime/qv4include.cpp b/src/qml/jsruntime/qv4include.cpp
index 3c378bf398..8983bea1a8 100644
--- a/src/qml/jsruntime/qv4include.cpp
+++ b/src/qml/jsruntime/qv4include.cpp
@@ -119,10 +119,10 @@ void QV4Include::callback(const QV4::Value &callback, const QV4::Value &status)
     if (!f)
         return;
 
-    QV4::ScopedCallData callData(scope, 1);
-    callData->thisObject = v4->globalObject->asReturnedValue();
-    callData->args[0] = status;
-    f->call(callData);
+    QV4::JSCall jsCall(scope, f, 1);
+    jsCall->thisObject = v4->globalObject->asReturnedValue();
+    jsCall->args[0] = status;
+    jsCall.call();
     if (scope.hasException())
         scope.engine->catchException();
 }
diff --git a/src/qml/jsruntime/qv4jscall_p.h b/src/qml/jsruntime/qv4jscall_p.h
index f871034789..c78337a89f 100644
--- a/src/qml/jsruntime/qv4jscall_p.h
+++ b/src/qml/jsruntime/qv4jscall_p.h
@@ -60,16 +60,15 @@ QT_BEGIN_NAMESPACE
 
 namespace QV4 {
 
-struct ScopedCallData {
-    ScopedCallData(const Scope &scope, int argc = 0)
+struct JSCall {
+    JSCall(const Scope &scope, std::nullptr_t, int argc = 0)
     {
         int size = int(offsetof(QV4::CallData, args)/sizeof(QV4::Value)) + qMax(argc , int(QV4::Global::ReservedArgumentCount));
         ptr = reinterpret_cast<CallData *>(scope.alloc(size));
         ptr->tag = quint32(QV4::Value::ValueTypeInternal::Integer);
         ptr->argc = argc;
     }
-
-    ScopedCallData(const Scope &scope, const FunctionObject *function, int argc = 0)
+    JSCall(const Scope &scope, const FunctionObject *function, int argc = 0)
     {
         int size = int(offsetof(QV4::CallData, args)/sizeof(QV4::Value)) + qMax(argc , int(QV4::Global::ReservedArgumentCount));
         ptr = reinterpret_cast<CallData *>(scope.alloc(size));
@@ -77,6 +76,14 @@ struct ScopedCallData {
         ptr->argc = argc;
         ptr->function = *function;
     }
+    JSCall(const Scope &scope, Heap::FunctionObject *function, int argc = 0)
+    {
+        int size = int(offsetof(QV4::CallData, args)/sizeof(QV4::Value)) + qMax(argc , int(QV4::Global::ReservedArgumentCount));
+        ptr = reinterpret_cast<CallData *>(scope.alloc(size));
+        ptr->tag = quint32(QV4::Value::ValueTypeInternal::Integer);
+        ptr->argc = argc;
+        ptr->function = function;
+    }
 
     CallData *operator->() {
         return ptr;
@@ -90,6 +97,10 @@ struct ScopedCallData {
         return static_cast<FunctionObject &>(ptr->function).call(ptr);
     }
 
+    ReturnedValue callAsConstructor() const {
+        return static_cast<FunctionObject &>(ptr->function).construct(ptr);
+    }
+
     CallData *ptr;
 };
 
diff --git a/src/qml/jsruntime/qv4jsonobject.cpp b/src/qml/jsruntime/qv4jsonobject.cpp
index 88fc0d6b3c..83cfb434dc 100644
--- a/src/qml/jsruntime/qv4jsonobject.cpp
+++ b/src/qml/jsruntime/qv4jsonobject.cpp
@@ -697,21 +697,21 @@ QString Stringify::Str(const QString &key, const Value &v)
         ScopedString s(scope, v4->newString(QStringLiteral("toJSON")));
         ScopedFunctionObject toJSON(scope, o->get(s));
         if (!!toJSON) {
-            ScopedCallData callData(scope, 1);
-            callData->thisObject = value;
-            callData->args[0] = v4->newString(key);
-            value = toJSON->call(callData);
+            JSCall jsCall(scope, toJSON, 1);
+            jsCall->thisObject = value;
+            jsCall->args[0] = v4->newString(key);
+            value = jsCall.call();
         }
     }
 
     if (replacerFunction) {
         ScopedObject holder(scope, v4->newObject());
         holder->put(scope.engine->id_empty(), value);
-        ScopedCallData callData(scope, 2);
-        callData->args[0] = v4->newString(key);
-        callData->args[1] = value;
-        callData->thisObject = holder;
-        value = replacerFunction->call(callData);
+        JSCall jsCall(scope, replacerFunction, 2);
+        jsCall->args[0] = v4->newString(key);
+        jsCall->args[1] = value;
+        jsCall->thisObject = holder;
+        value = jsCall.call();
     }
 
     o = value->asReturnedValue();
diff --git a/src/qml/jsruntime/qv4lookup.cpp b/src/qml/jsruntime/qv4lookup.cpp
index 392ab565b0..c612e8450c 100644
--- a/src/qml/jsruntime/qv4lookup.cpp
+++ b/src/qml/jsruntime/qv4lookup.cpp
@@ -400,9 +400,9 @@ ReturnedValue Lookup::getterAccessor0(Lookup *l, ExecutionEngine *engine, const
             if (!getter)
                 return Encode::undefined();
 
-            ScopedCallData callData(scope, 0);
-            callData->thisObject = object;
-            return getter->call(callData);
+            JSCall jsCall(scope, getter, 0);
+            jsCall->thisObject = object;
+            return jsCall.call();
         }
     }
     l->getter = getterFallback;
@@ -422,9 +422,9 @@ ReturnedValue Lookup::getterAccessor1(Lookup *l, ExecutionEngine *engine, const
             if (!getter)
                 return Encode::undefined();
 
-            ScopedCallData callData(scope, 0);
-            callData->thisObject = object;
-            return getter->call(callData);
+            JSCall jsCall(scope, getter, 0);
+            jsCall->thisObject = object;
+            return jsCall.call();
         }
     }
     l->getter = getterFallback;
@@ -447,9 +447,9 @@ ReturnedValue Lookup::getterAccessor2(Lookup *l, ExecutionEngine *engine, const
                     if (!getter)
                         return Encode::undefined();
 
-                    ScopedCallData callData(scope, 0);
-                    callData->thisObject = object;
-                    return getter->call(callData);
+                    JSCall jsCall(scope, getter, 0);
+                    jsCall->thisObject = object;
+                    return jsCall.call();
                 }
             }
         }
@@ -502,9 +502,9 @@ ReturnedValue Lookup::primitiveGetterAccessor0(Lookup *l, ExecutionEngine *engin
             if (!getter)
                 return Encode::undefined();
 
-            ScopedCallData callData(scope, 0);
-            callData->thisObject = object;
-            return getter->call(callData);
+            JSCall jsCall(scope, getter, 0);
+            jsCall->thisObject = object;
+            return jsCall.call();
         }
     }
     l->getter = getterGeneric;
@@ -522,9 +522,9 @@ ReturnedValue Lookup::primitiveGetterAccessor1(Lookup *l, ExecutionEngine *engin
             if (!getter)
                 return Encode::undefined();
 
-            ScopedCallData callData(scope, 0);
-            callData->thisObject = object;
-            return getter->call(callData);
+            JSCall jsCall(scope, getter, 0);
+            jsCall->thisObject = object;
+            return jsCall.call();
         }
     }
     l->getter = getterGeneric;
@@ -641,9 +641,8 @@ ReturnedValue Lookup::globalGetterAccessor0(Lookup *l, ExecutionEngine *engine)
         if (!getter)
             return Encode::undefined();
 
-        ScopedCallData callData(scope, 0);
-        callData->thisObject = Primitive::undefinedValue();
-        return getter->call(callData);
+        JSCall jsCall(scope, getter, 0);
+        return jsCall.call();
     }
     l->globalGetter = globalGetterGeneric;
     return globalGetterGeneric(l, engine);
@@ -659,9 +658,8 @@ ReturnedValue Lookup::globalGetterAccessor1(Lookup *l, ExecutionEngine *engine)
         if (!getter)
             return Encode::undefined();
 
-        ScopedCallData callData(scope, 0);
-        callData->thisObject = Primitive::undefinedValue();
-        return getter->call(callData);
+        JSCall jsCall(scope, getter, 0);
+        return jsCall.call();
     }
     l->globalGetter = globalGetterGeneric;
     return globalGetterGeneric(l, engine);
@@ -680,9 +678,8 @@ ReturnedValue Lookup::globalGetterAccessor2(Lookup *l, ExecutionEngine *engine)
                 if (!getter)
                     return Encode::undefined();
 
-                ScopedCallData callData(scope, 0);
-                callData->thisObject = Primitive::undefinedValue();
-                return getter->call(callData);
+                JSCall jsCall(scope, getter, 0);
+                return jsCall.call();
             }
         }
     }
diff --git a/src/qml/jsruntime/qv4object.cpp b/src/qml/jsruntime/qv4object.cpp
index b778a064be..d310c4b114 100644
--- a/src/qml/jsruntime/qv4object.cpp
+++ b/src/qml/jsruntime/qv4object.cpp
@@ -107,9 +107,9 @@ ReturnedValue Object::getValue(const Value &thisObject, const Value &v, Property
         return Encode::undefined();
 
     Scope scope(f->engine());
-    ScopedCallData callData(scope);
-    callData->thisObject = thisObject;
-    return f->call(callData);
+    JSCall jsCall(scope, f);
+    jsCall->thisObject = thisObject;
+    return jsCall.call();
 }
 
 bool Object::putValue(uint memberIndex, const Value &value)
@@ -125,10 +125,10 @@ bool Object::putValue(uint memberIndex, const Value &value)
         if (set) {
             Scope scope(ic->engine);
             ScopedFunctionObject setter(scope, set);
-            ScopedCallData callData(scope, 1);
-            callData->args[0] = value;
-            callData->thisObject = this;
-            setter->call(callData);
+            JSCall jsCall(scope, setter, 1);
+            jsCall->args[0] = value;
+            jsCall->thisObject = this;
+            jsCall.call();
             return !ic->engine->hasException;
         }
         return false;
@@ -764,11 +764,11 @@ bool Object::internalPut(String *name, const Value &value)
 
         Scope scope(engine);
         ScopedFunctionObject setter(scope, *memberIndex);
-        ScopedCallData callData(scope, 1);
-        callData->args[0] = value;
-        callData->thisObject = this;
-        setter->call(callData);
-        return !internalClass()->engine->hasException;
+        JSCall jsCall(scope, setter, 1);
+        jsCall->args[0] = value;
+        jsCall->thisObject = this;
+        jsCall.call();
+        return !engine->hasException;
     }
 
     insertMember(name, value);
@@ -829,11 +829,11 @@ bool Object::internalPutIndexed(uint index, const Value &value)
 
         Scope scope(engine);
         ScopedFunctionObject setter(scope, *arrayIndex);
-        ScopedCallData callData(scope, 1);
-        callData->args[0] = value;
-        callData->thisObject = this;
-        setter->call(callData);
-        return !internalClass()->engine->hasException;
+        JSCall jsCall(scope, setter, 1);
+        jsCall->args[0] = value;
+        jsCall->thisObject = this;
+        jsCall.call();
+        return !engine->hasException;
     }
 
     arraySet(index, value);
diff --git a/src/qml/jsruntime/qv4objectproto.cpp b/src/qml/jsruntime/qv4objectproto.cpp
index e7ef9d93cf..0f60881db1 100644
--- a/src/qml/jsruntime/qv4objectproto.cpp
+++ b/src/qml/jsruntime/qv4objectproto.cpp
@@ -479,9 +479,9 @@ ReturnedValue ObjectPrototype::method_toLocaleString(const BuiltinFunction *b, C
     ScopedFunctionObject f(scope, o->get(scope.engine->id_toString()));
     if (!f)
         THROW_TYPE_ERROR();
-    ScopedCallData cData(scope);
-    cData->thisObject = o;
-    return f->call(callData);
+    JSCall jsCall(scope, f);
+    jsCall->thisObject = o;
+    return jsCall.call();
 }
 
 ReturnedValue ObjectPrototype::method_valueOf(const BuiltinFunction *b, CallData *callData)
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index ddce96f9ca..40dfeefdcc 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -816,18 +816,18 @@ struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
             QV4::Scope scope(v4);
             QV4::ScopedFunctionObject f(scope, This->function.value());
 
-            QV4::ScopedCallData callData(scope, argCount);
-            callData->thisObject = This->thisObject.isUndefined() ? v4->globalObject->asReturnedValue() : This->thisObject.value();
+            QV4::JSCall jsCall(scope, f, argCount);
+            jsCall->thisObject = This->thisObject.isUndefined() ? v4->globalObject->asReturnedValue() : This->thisObject.value();
             for (int ii = 0; ii < argCount; ++ii) {
                 int type = argsTypes[ii + 1];
                 if (type == qMetaTypeId<QVariant>()) {
-                    callData->args[ii] = v4->fromVariant(*((QVariant *)metaArgs[ii + 1]));
+                    jsCall->args[ii] = v4->fromVariant(*((QVariant *)metaArgs[ii + 1]));
                 } else {
-                    callData->args[ii] = v4->fromVariant(QVariant(type, metaArgs[ii + 1]));
+                    jsCall->args[ii] = v4->fromVariant(QVariant(type, metaArgs[ii + 1]));
                 }
             }
 
-            f->call(callData);
+            jsCall.call();
             if (scope.hasException()) {
                 QQmlError error = v4->catchExceptionAsQmlError();
                 if (error.description().isEmpty()) {
diff --git a/src/qml/jsruntime/qv4regexpobject.cpp b/src/qml/jsruntime/qv4regexpobject.cpp
index 4124188b59..db5551f99c 100644
--- a/src/qml/jsruntime/qv4regexpobject.cpp
+++ b/src/qml/jsruntime/qv4regexpobject.cpp
@@ -394,10 +394,10 @@ ReturnedValue RegExpPrototype::method_compile(const BuiltinFunction *b, CallData
     if (!r)
         return scope.engine->throwTypeError();
 
-    ScopedCallData cData(scope, callData->argc);
-    memcpy(cData->args, callData->args, callData->argc*sizeof(Value));
+    JSCall jsCall(scope, scope.engine->regExpCtor(), callData->argc);
+    memcpy(jsCall->args, callData->args, callData->argc*sizeof(Value));
 
-    Scoped<RegExpObject> re(scope, scope.engine->regExpCtor()->as<FunctionObject>()->construct(cData));
+    Scoped<RegExpObject> re(scope, jsCall.callAsConstructor());
 
     r->d()->value.set(scope.engine, re->value());
     r->d()->global = re->global();
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 187cd7c313..f09d803d0b 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -424,12 +424,13 @@ ReturnedValue RuntimeHelpers::objectDefaultValue(const Object *object, int typeH
         qSwap(meth1, meth2);
 
     Scope scope(engine);
-    ScopedCallData callData(scope, 0);
-    callData->thisObject = *object;
+    JSCall jsCall(scope, nullptr, 0);
+    jsCall->thisObject = *object;
 
     ScopedValue conv(scope, object->get(meth1));
     if (FunctionObject *o = conv->as<FunctionObject>()) {
-        ScopedValue r(scope, o->call(callData));
+        jsCall->function = o;
+        ScopedValue r(scope, jsCall.call());
         if (r->isPrimitive())
             return r->asReturnedValue();
     }
@@ -439,7 +440,8 @@ ReturnedValue RuntimeHelpers::objectDefaultValue(const Object *object, int typeH
 
     conv = object->get(meth2);
     if (FunctionObject *o = conv->as<FunctionObject>()) {
-        ScopedValue r(scope, o->call(callData));
+        jsCall->function = o;
+        ScopedValue r(scope, jsCall.call());
         if (r->isPrimitive())
             return r->asReturnedValue();
     }
diff --git a/src/qml/jsruntime/qv4script.cpp b/src/qml/jsruntime/qv4script.cpp
index 598c12ffd4..c3200fbcea 100644
--- a/src/qml/jsruntime/qv4script.cpp
+++ b/src/qml/jsruntime/qv4script.cpp
@@ -152,16 +152,16 @@ ReturnedValue Script::run()
         ContextStateSaver stateSaver(valueScope, scope);
         scope->d()->v4Function = vmFunction;
 
-        QV4::ScopedCallData cData(scope);
-        cData->thisObject = engine->globalObject;
-        cData->context = *scope;
-        return vmFunction->call(cData);
+        QV4::JSCall jsCall(scope, nullptr);
+        jsCall->thisObject = engine->globalObject;
+        jsCall->context = *scope;
+        return vmFunction->call(jsCall);
     } else {
         Scoped<QmlContext> qml(valueScope, qmlContext.value());
-        ScopedCallData callData(valueScope);
-        callData->thisObject = Primitive::undefinedValue();
-        callData->context = *qml;
-        return vmFunction->call(callData);
+        JSCall jsCall(valueScope, nullptr);
+        jsCall->thisObject = Primitive::undefinedValue();
+        jsCall->context = *qml;
+        return vmFunction->call(jsCall);
     }
 }
 
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index ed9f798cd7..28b20169d9 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -417,12 +417,14 @@ public:
         bool operator()(typename Container::value_type lhs, typename Container::value_type rhs)
         {
             QV4::Scope scope(m_v4);
-            ScopedObject compare(scope, m_compareFn);
-            ScopedCallData callData(scope, 2);
-            callData->args[0] = convertElementToValue(m_v4, lhs);
-            callData->args[1] = convertElementToValue(m_v4, rhs);
-            callData->thisObject = m_v4->globalObject;
-            QV4::ScopedValue result(scope, compare->call(callData));
+            ScopedFunctionObject compare(scope, m_compareFn);
+            if (!compare)
+                return m_v4->throwTypeError();
+            JSCall jsCall(scope, compare, 2);
+            jsCall->args[0] = convertElementToValue(m_v4, lhs);
+            jsCall->args[1] = convertElementToValue(m_v4, rhs);
+            jsCall->thisObject = m_v4->globalObject;
+            QV4::ScopedValue result(scope, jsCall.call());
             return result->toNumber() < 0;
         }
 
diff --git a/src/qml/jsruntime/qv4stringobject.cpp b/src/qml/jsruntime/qv4stringobject.cpp
index 4964769b88..66ad5e79d2 100644
--- a/src/qml/jsruntime/qv4stringobject.cpp
+++ b/src/qml/jsruntime/qv4stringobject.cpp
@@ -411,9 +411,9 @@ ReturnedValue StringPrototype::method_match(const BuiltinFunction *b, CallData *
     ScopedValue regexp(scope, callData->argument(0));
     Scoped<RegExpObject> rx(scope, regexp);
     if (!rx) {
-        ScopedCallData callData(scope, 1);
-        callData->args[0] = regexp;
-        rx = scope.engine->regExpCtor()->construct(callData);
+        JSCall jsCall(scope, scope.engine->regExpCtor(), 1);
+        jsCall->args[0] = regexp;
+        rx = jsCall.callAsConstructor();
     }
 
     if (!rx)
@@ -426,11 +426,11 @@ ReturnedValue StringPrototype::method_match(const BuiltinFunction *b, CallData *
     ScopedString execString(scope, scope.engine->newString(QStringLiteral("exec")));
     ScopedFunctionObject exec(scope, scope.engine->regExpPrototype()->get(execString));
 
-    ScopedCallData cData(scope, 1);
-    cData->thisObject = rx;
-    cData->args[0] = s;
+    JSCall jsCall(scope, exec, 1);
+    jsCall->thisObject = rx;
+    jsCall->args[0] = s;
     if (!global)
-        return exec->call(cData);
+        return jsCall.call();
 
     ScopedString lastIndex(scope, scope.engine->newString(QStringLiteral("lastIndex")));
     rx->put(lastIndex, ScopedValue(scope, Primitive::fromInt32(0)));
@@ -442,7 +442,7 @@ ReturnedValue StringPrototype::method_match(const BuiltinFunction *b, CallData *
     ScopedValue index(scope);
     ScopedValue result(scope);
     while (1) {
-        result = exec->call(cData);
+        result = jsCall.call();
         if (result->isNull())
             break;
         assert(result->isObject());
@@ -590,8 +590,8 @@ ReturnedValue StringPrototype::method_replace(const BuiltinFunction *b, CallData
     ScopedFunctionObject searchCallback(scope, replaceValue);
     if (!!searchCallback) {
         result.reserve(string.length() + 10*numStringMatches);
-        ScopedCallData callData(scope, numCaptures + 2);
-        callData->thisObject = Primitive::undefinedValue();
+        JSCall jsCall(scope, searchCallback, numCaptures + 2);
+        jsCall->thisObject = Primitive::undefinedValue();
         int lastEnd = 0;
         ScopedValue entry(scope);
         for (int i = 0; i < numStringMatches; ++i) {
@@ -602,15 +602,15 @@ ReturnedValue StringPrototype::method_replace(const BuiltinFunction *b, CallData
                 entry = Primitive::undefinedValue();
                 if (start != JSC::Yarr::offsetNoMatch && end != JSC::Yarr::offsetNoMatch)
                     entry = scope.engine->newString(string.mid(start, end - start));
-                callData->args[k] = entry;
+                jsCall->args[k] = entry;
             }
             uint matchStart = matchOffsets[i * numCaptures * 2];
             Q_ASSERT(matchStart >= static_cast<uint>(lastEnd));
             uint matchEnd = matchOffsets[i * numCaptures * 2 + 1];
-            callData->args[numCaptures] = Primitive::fromUInt32(matchStart);
-            callData->args[numCaptures + 1] = scope.engine->newString(string);
+            jsCall->args[numCaptures] = Primitive::fromUInt32(matchStart);
+            jsCall->args[numCaptures + 1] = scope.engine->newString(string);
 
-            replacement = searchCallback->call(callData);
+            replacement = jsCall.call();
             result += string.midRef(lastEnd, matchStart - lastEnd);
             result += replacement->toQString();
             lastEnd = matchEnd;
@@ -652,9 +652,9 @@ ReturnedValue StringPrototype::method_search(const BuiltinFunction *b, CallData
 
     RegExpObject *regExp = regExpObj->as<RegExpObject>();
     if (!regExp) {
-        ScopedCallData callData(scope, 1);
-        callData->args[0] = regExpObj;
-        regExpObj = scope.engine->regExpCtor()->construct(callData);
+        JSCall jsCall(scope, scope.engine->regExpCtor(), 1);
+        jsCall->args[0] = regExpObj;
+        regExpObj = jsCall.callAsConstructor();
         if (scope.engine->hasException)
             return QV4::Encode::undefined();
 
diff --git a/src/qml/jsruntime/qv4typedarray.cpp b/src/qml/jsruntime/qv4typedarray.cpp
index 3d0acb19b9..5bec5046fe 100644
--- a/src/qml/jsruntime/qv4typedarray.cpp
+++ b/src/qml/jsruntime/qv4typedarray.cpp
@@ -572,9 +572,9 @@ ReturnedValue TypedArrayPrototype::method_subarray(const BuiltinFunction *builti
     if (!constructor)
         return scope.engine->throwTypeError();
 
-    ScopedCallData cData(scope, 3);
-    cData->args[0] = buffer;
-    cData->args[1] = Encode(a->d()->byteOffset + begin*a->d()->type->bytesPerElement);
-    cData->args[2] = Encode(newLen);
-    return constructor->construct(cData);
+    JSCall jsCall(scope, constructor, 3);
+    jsCall->args[0] = buffer;
+    jsCall->args[1] = Encode(a->d()->byteOffset + begin*a->d()->type->bytesPerElement);
+    jsCall->args[2] = Encode(newLen);
+    return jsCall.callAsConstructor();
 }
diff --git a/src/qml/qml/qqmlboundsignal.cpp b/src/qml/qml/qqmlboundsignal.cpp
index 20c84b34e6..ba2f37eb2d 100644
--- a/src/qml/qml/qqmlboundsignal.cpp
+++ b/src/qml/qml/qqmlboundsignal.cpp
@@ -193,35 +193,35 @@ void QQmlBoundSignalExpression::evaluate(void **a)
     int *argsTypes = QQmlMetaObject(m_target).methodParameterTypes(methodIndex, &storage, 0);
     int argCount = argsTypes ? *argsTypes : 0;
 
-    QV4::ScopedCallData callData(scope, argCount);
+    QV4::JSCall jsCall(scope, nullptr, argCount);
     for (int ii = 0; ii < argCount; ++ii) {
         int type = argsTypes[ii + 1];
         //### ideally we would use metaTypeToJS, however it currently gives different results
         //    for several cases (such as QVariant type and QObject-derived types)
         //args[ii] = engine->metaTypeToJS(type, a[ii + 1]);
         if (type == qMetaTypeId<QJSValue>()) {
-            if (QV4::Value *v4Value = QJSValuePrivate::valueForData(reinterpret_cast<QJSValue *>(a[ii + 1]), &callData->args[ii]))
-                callData->args[ii] = *v4Value;
+            if (QV4::Value *v4Value = QJSValuePrivate::valueForData(reinterpret_cast<QJSValue *>(a[ii + 1]), &jsCall->args[ii]))
+                jsCall->args[ii] = *v4Value;
             else
-                callData->args[ii] = QV4::Encode::undefined();
+                jsCall->args[ii] = QV4::Encode::undefined();
         } else if (type == QMetaType::QVariant) {
-            callData->args[ii] = scope.engine->fromVariant(*((QVariant *)a[ii + 1]));
+            jsCall->args[ii] = scope.engine->fromVariant(*((QVariant *)a[ii + 1]));
         } else if (type == QMetaType::Int) {
             //### optimization. Can go away if we switch to metaTypeToJS, or be expanded otherwise
-            callData->args[ii] = QV4::Primitive::fromInt32(*reinterpret_cast<const int*>(a[ii + 1]));
+            jsCall->args[ii] = QV4::Primitive::fromInt32(*reinterpret_cast<const int*>(a[ii + 1]));
         } else if (type == qMetaTypeId<QQmlV4Handle>()) {
-            callData->args[ii] = *reinterpret_cast<QQmlV4Handle *>(a[ii + 1]);
+            jsCall->args[ii] = *reinterpret_cast<QQmlV4Handle *>(a[ii + 1]);
         } else if (ep->isQObject(type)) {
             if (!*reinterpret_cast<void* const *>(a[ii + 1]))
-                callData->args[ii] = QV4::Primitive::nullValue();
+                jsCall->args[ii] = QV4::Primitive::nullValue();
             else
-                callData->args[ii] = QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1]));
+                jsCall->args[ii] = QV4::QObjectWrapper::wrap(ep->v4engine(), *reinterpret_cast<QObject* const *>(a[ii + 1]));
         } else {
-            callData->args[ii] = scope.engine->fromVariant(QVariant(type, a[ii + 1]));
+            jsCall->args[ii] = scope.engine->fromVariant(QVariant(type, a[ii + 1]));
         }
     }
 
-    QQmlJavaScriptExpression::evaluate(callData, 0);
+    QQmlJavaScriptExpression::evaluate(jsCall, 0);
 
     ep->dereferenceScarceResources(); // "release" scarce resources if top-level expression evaluation is complete.
 }
@@ -238,12 +238,12 @@ void QQmlBoundSignalExpression::evaluate(const QList<QVariant> &args)
 
     ep->referenceScarceResources(); // "hold" scarce resources in memory during evaluation.
 
-    QV4::ScopedCallData callData(scope, args.count());
+    QV4::JSCall jsCall(scope, nullptr, args.count());
     for (int ii = 0; ii < args.count(); ++ii) {
-        callData->args[ii] = scope.engine->fromVariant(args[ii]);
+        jsCall->args[ii] = scope.engine->fromVariant(args[ii]);
     }
 
-    QQmlJavaScriptExpression::evaluate(callData, 0);
+    QQmlJavaScriptExpression::evaluate(jsCall, 0);
 
     ep->dereferenceScarceResources(); // "release" scarce resources if top-level expression evaluation is complete.
 }
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index 4affc5a453..dd0d2096ce 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -1547,10 +1547,10 @@ void QV4::QmlIncubatorObject::statusChanged(QQmlIncubator::Status s)
 
     QV4::ScopedFunctionObject f(scope, d()->statusChanged);
     if (f) {
-        QV4::ScopedCallData callData(scope, 1);
-        callData->thisObject = this;
-        callData->args[0] = QV4::Primitive::fromUInt32(s);
-        f->call(callData);
+        QV4::JSCall jsCall(scope, f, 1);
+        jsCall->thisObject = this;
+        jsCall->args[0] = QV4::Primitive::fromUInt32(s);
+        jsCall.call();
         if (scope.hasException()) {
             QQmlError error = scope.engine->catchExceptionAsQmlError();
             QQmlEnginePrivate::warning(QQmlEnginePrivate::get(scope.engine->qmlEngine()), error);
diff --git a/src/qml/qml/qqmldelayedcallqueue.cpp b/src/qml/qml/qqmldelayedcallqueue.cpp
index 87b6fac10e..1537657e0d 100644
--- a/src/qml/qml/qqmldelayedcallqueue.cpp
+++ b/src/qml/qml/qqmldelayedcallqueue.cpp
@@ -64,17 +64,17 @@ void QQmlDelayedCallQueue::DelayedFunctionCall::execute(QV4::ExecutionEngine *en
         QV4::Scope scope(engine);
 
         QV4::ArrayObject *array = m_args.as<QV4::ArrayObject>();
+        const QV4::FunctionObject *callback = m_function.as<QV4::FunctionObject>();
+        Q_ASSERT(callback);
         const int argCount = array ? array->getLength() : 0;
-        QV4::ScopedCallData callData(scope, argCount);
-        callData->thisObject = QV4::Encode::undefined();
+        QV4::JSCall jsCall(scope, callback, argCount);
+        jsCall->thisObject = QV4::Encode::undefined();
 
         for (int i = 0; i < argCount; i++) {
-            callData->args[i] = array->getIndexed(i);
+            jsCall->args[i] = array->getIndexed(i);
         }
 
-        const QV4::FunctionObject *callback = m_function.as<QV4::FunctionObject>();
-        Q_ASSERT(callback);
-        callback->call(callData);
+        jsCall.call();
 
         if (scope.engine->hasException) {
             QQmlError error = scope.engine->catchExceptionAsQmlError();
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index 36881f02ba..e40795283a 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -185,9 +185,9 @@ QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(bool *isUndefined)
 {
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(m_context->engine);
     QV4::Scope scope(v4);
-    QV4::ScopedCallData callData(scope);
+    QV4::JSCall jsCall(scope, nullptr);
 
-    return evaluate(callData, isUndefined);
+    return evaluate(jsCall, isUndefined);
 }
 
 QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QV4::CallData *callData, bool *isUndefined)
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index 3510367fd3..2b54819ad0 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -951,14 +951,13 @@ int QQmlVMEMetaObject::metaCall(QObject *o, QMetaObject::Call c, int _id, void *
                 }
 
                 const unsigned int parameterCount = function->formalParameterCount();
-                QV4::ScopedCallData callData(scope, parameterCount);
-                callData->thisObject = ep->v8engine()->global();
+                QV4::JSCall jsCall(scope, function, parameterCount);
+                jsCall->thisObject = ep->v8engine()->global();
 
                 for (uint ii = 0; ii < parameterCount; ++ii)
-                    callData->args[ii] = scope.engine->fromVariant(*(QVariant *)a[ii + 1]);
+                    jsCall->args[ii] = scope.engine->fromVariant(*(QVariant *)a[ii + 1]);
 
-                QV4::ScopedValue result(scope);
-                result = function->call(callData);
+                QV4::ScopedValue result(scope, jsCall.call());
                 if (scope.hasException()) {
                     QQmlError error = scope.engine->catchExceptionAsQmlError();
                     if (error.isValid())
diff --git a/src/qml/qml/qqmlxmlhttprequest.cpp b/src/qml/qml/qqmlxmlhttprequest.cpp
index a77c4c5678..21f1fb30b0 100644
--- a/src/qml/qml/qqmlxmlhttprequest.cpp
+++ b/src/qml/qml/qqmlxmlhttprequest.cpp
@@ -1576,9 +1576,7 @@ void QQmlXMLHttpRequest::dispatchCallback(Object *thisObj, QQmlContextData *cont
         return;
     }
 
-    QV4::ScopedCallData callData(scope);
-    callData->thisObject = Encode::undefined();
-    callback->call(callData);
+    QV4::JSCall(scope, callback).call();
 
     if (scope.engine->hasException) {
         QQmlError error = scope.engine->catchExceptionAsQmlError();
diff --git a/src/qml/types/qquickworkerscript.cpp b/src/qml/types/qquickworkerscript.cpp
index a26bd81c8b..6df15c2513 100644
--- a/src/qml/types/qquickworkerscript.cpp
+++ b/src/qml/types/qquickworkerscript.cpp
@@ -248,10 +248,10 @@ void QQuickWorkerScriptEnginePrivate::WorkerEngine::init()
     QV4::ScopedString name(scope, m_v4Engine->newString(QStringLiteral("sendMessage")));
     QV4::ScopedValue function(scope, QV4::BuiltinFunction::create(globalContext, name,
                                                                   QQuickWorkerScriptEnginePrivate::method_sendMessage));
-    QV4::ScopedCallData callData(scope, 1);
-    callData->args[0] = function;
-    callData->thisObject = global();
-    createsend.set(scope.engine, createsendconstructor->call(callData));
+    QV4::JSCall jsCall(scope, createsendconstructor, 1);
+    jsCall->args[0] = function;
+    jsCall->thisObject = global();
+    createsend.set(scope.engine, jsCall.call());
 }
 
 // Requires handle and context scope
@@ -265,10 +265,10 @@ QV4::ReturnedValue QQuickWorkerScriptEnginePrivate::WorkerEngine::sendFunction(i
     QV4::ScopedFunctionObject f(scope, createsend.value());
 
     QV4::ScopedValue v(scope);
-    QV4::ScopedCallData callData(scope, 1);
-    callData->args[0] = QV4::Primitive::fromInt32(id);
-    callData->thisObject = global();
-    v = f->call(callData);
+    QV4::JSCall jsCall(scope, f, 1);
+    jsCall->args[0] = QV4::Primitive::fromInt32(id);
+    jsCall->thisObject = global();
+    v = jsCall.call();
     if (scope.hasException())
         v = scope.engine->catchException();
     return v->asReturnedValue();
@@ -366,11 +366,11 @@ void QQuickWorkerScriptEnginePrivate::processMessage(int id, const QByteArray &d
     QV4::Scoped<QV4::QmlContext> qmlContext(scope, script->qmlContext.value());
     Q_ASSERT(!!qmlContext);
 
-    QV4::ScopedCallData callData(scope, 2);
-    callData->thisObject = workerEngine->global();
-    callData->args[0] = qmlContext->d()->qml(); // ###
-    callData->args[1] = value;
-    f->call(callData);
+    QV4::JSCall jsCall(scope, f, 2);
+    jsCall->thisObject = workerEngine->global();
+    jsCall->args[0] = qmlContext->d()->qml(); // ###
+    jsCall->args[1] = value;
+    jsCall.call();
     if (scope.hasException()) {
         QQmlError error = scope.engine->catchExceptionAsQmlError();
         reportScriptException(script, error);
diff --git a/src/quick/items/context2d/qquickcanvasitem.cpp b/src/quick/items/context2d/qquickcanvasitem.cpp
index ddf34666a2..ff90a74c43 100644
--- a/src/quick/items/context2d/qquickcanvasitem.cpp
+++ b/src/quick/items/context2d/qquickcanvasitem.cpp
@@ -729,13 +729,13 @@ 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);
+        QV4::JSCall jsCall(scope, nullptr, 1);
+        jsCall->thisObject = QV4::QObjectWrapper::wrap(v4, this);
 
         for (auto it = animationCallbacks.cbegin(), end = animationCallbacks.cend(); it != end; ++it) {
-            QV4::ScopedFunctionObject f(scope, it.value().value());
-            callData->args[0] = QV4::Primitive::fromUInt32(QDateTime::currentMSecsSinceEpoch() / 1000);
-            f->call(callData);
+            jsCall->function = it.value().value();
+            jsCall->args[0] = QV4::Primitive::fromUInt32(QDateTime::currentMSecsSinceEpoch() / 1000);
+            jsCall.call();
         }
     }
     else {