Reduce memory consumption of signal handlers

Move the connect/disconnect methods for signal handlers into
their prototype, so that we don't need to define them per instance
anymore.

Change-Id: Iac1e6d1dd7bce86730dbb6c51e2c3f79713641f7
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

4 files changed, 23 insertions, 8 deletions

diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index d5a47273a9..6fe14da850 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -429,6 +429,7 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     jsObjects[DataViewProto] = memoryManager->allocObject<DataViewPrototype>();
     static_cast<DataViewPrototype *>(dataViewPrototype())->init(this, dataViewCtor());
     jsObjects[ValueTypeProto] = (Heap::Base *) 0;
+    jsObjects[SignalHandlerProto] = (Heap::Base *) 0;
 
     for (int i = 0; i < Heap::TypedArray::NTypes; ++i) {
         static_cast<Value &>(typedArrayCtors[i]) = memoryManager->allocObject<TypedArrayCtor>(global, Heap::TypedArray::Type(i));
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index 09cfbd226c..ffcd904013 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -149,6 +149,7 @@ public:
         ArrayBufferProto,
         DataViewProto,
         ValueTypeProto,
+        SignalHandlerProto,
 
         Object_Ctor,
         String_Ctor,
@@ -219,6 +220,7 @@ public:
     Object *typedArrayPrototype;
 
     Object *valueTypeWrapperPrototype() const { return reinterpret_cast<Object *>(jsObjects + ValueTypeProto); }
+    Object *signalHandlerPrototype() const { return reinterpret_cast<Object *>(jsObjects + SignalHandlerProto); }
 
     InternalClassPool *classPool;
     InternalClass *emptyClass;
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index c80b22b16b..5428d0d5ea 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -335,14 +335,8 @@ ReturnedValue QObjectWrapper::getProperty(ExecutionEngine *engine, QObject *obje
             ScopedContext global(scope, scope.engine->qmlContext());
             return QV4::QObjectMethod::create(global, object, property->coreIndex);
         } else if (property->isSignalHandler()) {
-            QV4::Scoped<QV4::QmlSignalHandler> handler(scope, scope.engine->memoryManager->allocObject<QV4::QmlSignalHandler>(object, property->coreIndex));
-
-            QV4::ScopedString connect(scope, engine->newIdentifier(QStringLiteral("connect")));
-            QV4::ScopedString disconnect(scope, engine->newIdentifier(QStringLiteral("disconnect")));
-            handler->put(connect, QV4::ScopedValue(scope, engine->functionPrototype()->get(connect)));
-            handler->put(disconnect, QV4::ScopedValue(scope, engine->functionPrototype()->get(disconnect)));
-
-            return handler.asReturnedValue();
+            QmlSignalHandler::initProto(engine);
+            return engine->memoryManager->allocObject<QV4::QmlSignalHandler>(object, property->coreIndex)->asReturnedValue();
         } else {
             ExecutionContext *global = scope.engine->rootContext();
             return QV4::QObjectMethod::create(global, object, property->coreIndex);
@@ -1891,6 +1885,21 @@ Heap::QmlSignalHandler::QmlSignalHandler(QObject *object, int signalIndex)
 
 DEFINE_OBJECT_VTABLE(QmlSignalHandler);
 
+void QmlSignalHandler::initProto(ExecutionEngine *engine)
+{
+    if (engine->signalHandlerPrototype()->d())
+        return;
+
+    Scope scope(engine);
+    ScopedObject o(scope, engine->newObject());
+    QV4::ScopedString connect(scope, engine->newIdentifier(QStringLiteral("connect")));
+    QV4::ScopedString disconnect(scope, engine->newIdentifier(QStringLiteral("disconnect")));
+    o->put(connect, QV4::ScopedValue(scope, engine->functionPrototype()->get(connect)));
+    o->put(disconnect, QV4::ScopedValue(scope, engine->functionPrototype()->get(disconnect)));
+
+    engine->jsObjects[QV4::ExecutionEngine::SignalHandlerProto] = o->d();
+}
+
 void MultiplyWrappedQObjectMap::insert(QObject *key, Heap::Object *value)
 {
     QV4::WeakValue v;
diff --git a/src/qml/jsruntime/qv4qobjectwrapper_p.h b/src/qml/jsruntime/qv4qobjectwrapper_p.h
index b035e478f9..1126013806 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper_p.h
+++ b/src/qml/jsruntime/qv4qobjectwrapper_p.h
@@ -169,10 +169,13 @@ struct Q_QML_EXPORT QObjectMethod : public QV4::FunctionObject
 struct QmlSignalHandler : public QV4::Object
 {
     V4_OBJECT2(QmlSignalHandler, QV4::Object)
+    V4_PROTOTYPE(signalHandlerPrototype)
     V4_NEEDS_DESTROY
 
     int signalIndex() const { return d()->signalIndex; }
     QObject *object() const { return d()->object.data(); }
+
+    static void initProto(ExecutionEngine *v4);
 };
 
 class MultiplyWrappedQObjectMap : public QObject,