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>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index eacb928901..3940176107 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -189,11 +189,12 @@ void QQmlBinding::update(QQmlPropertyPrivate::WriteFlags flags)
 
         bool isUndefined = false;
 
-        QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(&isUndefined));
+        QV4::ScopedCallData callData(scope);
+        QQmlJavaScriptExpression::evaluate(callData, &isUndefined, scope);
 
         bool error = false;
         if (!watcher.wasDeleted() && isAddedToObject() && !hasError())
-            error = !write(pd, result, isUndefined, flags);
+            error = !write(pd, scope.result, isUndefined, flags);
 
         if (!watcher.wasDeleted()) {
 
@@ -377,11 +378,12 @@ QVariant QQmlBinding::evaluate()
     bool isUndefined = false;
 
     QV4::Scope scope(ep->v4engine());
-    QV4::ScopedValue result(scope, QQmlJavaScriptExpression::evaluate(&isUndefined));
+    QV4::ScopedCallData callData(scope);
+    QQmlJavaScriptExpression::evaluate(callData, &isUndefined, scope);
 
     ep->dereferenceScarceResources();
 
-    return scope.engine->toVariant(result, qMetaTypeId<QList<QObject*> >());
+    return scope.engine->toVariant(scope.result, qMetaTypeId<QList<QObject*> >());
 }
 
 QString QQmlBinding::expressionIdentifier()