V4: Pass scope around as parameters inside the runtime.

The implementation of many (or all) runtime functions consist of first
creating a QV4::Scope, which saves and restores the JS stack pointer.
It also prevents tail-calls because of that restoring behavior. In many
cases it suffices to do that at the entry-point of the runtime.

The return value of a JS function call is now also stored in the scope.
Previously, all return values were stored in a ScopedValue, got loaded
on return, and immediately stored in another ScopedValue in the caller.
This resulted in a lot of stores, where now there is only one store
needed, and no extra ScopedValue for every function.

Change-Id: I13d80fc0ce72c5702ef1536d41d12f710c5914fa
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 12 insertions, 12 deletions

diff --git a/src/qml/types/qqmldelegatemodel.cpp b/src/qml/types/qqmldelegatemodel.cpp
index 1585f3eda0..9a1d9e50d1 100644
--- a/src/qml/types/qqmldelegatemodel.cpp
+++ b/src/qml/types/qqmldelegatemodel.cpp
@@ -91,17 +91,17 @@ struct DelegateModelGroupFunction : QV4::FunctionObject
         return scope->engine()->memoryManager->allocObject<DelegateModelGroupFunction>(scope, flag, code);
     }
 
-    static QV4::ReturnedValue call(const QV4::Managed *that, QV4::CallData *callData)
+    static void call(const QV4::Managed *that, QV4::Scope &scope, QV4::CallData *callData)
     {
-        QV4::ExecutionEngine *v4 = static_cast<const DelegateModelGroupFunction *>(that)->engine();
-        QV4::Scope scope(v4);
         QV4::Scoped<DelegateModelGroupFunction> f(scope, static_cast<const DelegateModelGroupFunction *>(that));
         QV4::Scoped<QQmlDelegateModelItemObject> o(scope, callData->thisObject);
-        if (!o)
-            return v4->throwTypeError(QStringLiteral("Not a valid VisualData object"));
+        if (!o) {
+            scope.result = scope.engine->throwTypeError(QStringLiteral("Not a valid VisualData object"));
+            return;
+        }
 
         QV4::ScopedValue v(scope, callData->argument(0));
-        return f->d()->code(o->d()->item, f->d()->flag, v);
+        scope.result = f->d()->code(o->d()->item, f->d()->flag, v);
     }
 };
 
diff --git a/src/qml/types/qquickworkerscript.cpp b/src/qml/types/qquickworkerscript.cpp
index bc15b2fd9b..10666476fe 100644
--- a/src/qml/types/qquickworkerscript.cpp
+++ b/src/qml/types/qquickworkerscript.cpp
@@ -251,7 +251,8 @@ void QQuickWorkerScriptEnginePrivate::WorkerEngine::init()
     QV4::ScopedCallData callData(scope, 1);
     callData->args[0] = function;
     callData->thisObject = global();
-    createsend.set(scope.engine, createsendconstructor->call(callData));
+    createsendconstructor->call(scope, callData);
+    createsend.set(scope.engine, scope.result.asReturnedValue());
 }
 
 // Requires handle and context scope
@@ -264,14 +265,13 @@ QV4::ReturnedValue QQuickWorkerScriptEnginePrivate::WorkerEngine::sendFunction(i
     QV4::Scope scope(v4);
     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);
+    f->call(scope, callData);
     if (scope.hasException())
-        v = scope.engine->catchException();
-    return v->asReturnedValue();
+        scope.result = scope.engine->catchException();
+    return scope.result.asReturnedValue();
 }
 
 #ifndef QT_NO_NETWORK
@@ -380,7 +380,7 @@ void QQuickWorkerScriptEnginePrivate::processMessage(int id, const QByteArray &d
     callData->thisObject = workerEngine->global();
     callData->args[0] = qmlContext->d()->qml; // ###
     callData->args[1] = value;
-    f->call(callData);
+    f->call(scope, callData);
     if (scope.hasException()) {
         QQmlError error = scope.engine->catchExceptionAsQmlError();
         reportScriptException(script, error);