Improve memory usage in QML/V4 engine.

* Don't create prototype Object for bindings and
  signal handlers. It is inaccessible and not required.
  This saves one Object-sized allocation per binding.
* Shrink the size of QQmlContextWrapper by removing
  the v8 member variable.
* Shrink the size of QObjectWrapper by moving the destroy
  identifier to the engine.

Change-Id: I76e84e4c0581e97a19d2e959f814ac84d9c431fa
Task-number: QTBUG-37134
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

4 files changed, 8 insertions, 8 deletions

diff --git a/src/qml/qml/qqmlcontextwrapper.cpp b/src/qml/qml/qqmlcontextwrapper.cpp
index d221e072f7..1660e3aeb1 100644
--- a/src/qml/qml/qqmlcontextwrapper.cpp
+++ b/src/qml/qml/qqmlcontextwrapper.cpp
@@ -63,7 +63,7 @@ DEFINE_OBJECT_VTABLE(QmlContextWrapper);
 
 QmlContextWrapper::QmlContextWrapper(QV8Engine *engine, QQmlContextData *context, QObject *scopeObject, bool ownsContext)
     : Object(QV8Engine::getV4(engine)),
-      v8(engine), readOnly(true), ownsContext(ownsContext), isNullWrapper(false),
+      readOnly(true), ownsContext(ownsContext), isNullWrapper(false),
       context(context), scopeObject(scopeObject), idObjectsWrapper(0)
 {
     setVTable(staticVTable());
@@ -181,7 +181,7 @@ ReturnedValue QmlContextWrapper::get(Managed *m, const StringRef name, bool *has
     //     context = context->parent
     // }
 
-    QV8Engine *engine = resource->v8;
+    QV8Engine *engine = v4->v8Engine;
 
     QObject *scopeObject = resource->getScopeObject();
 
@@ -413,7 +413,7 @@ ReturnedValue QmlContextWrapper::idObjectsArray()
     return idObjectsWrapper->asReturnedValue();
 }
 
-ReturnedValue QmlContextWrapper::qmlSingletonWrapper(const StringRef &name)
+ReturnedValue QmlContextWrapper::qmlSingletonWrapper(QV8Engine *v8, const StringRef &name)
 {
     if (!context->imports)
         return Encode::undefined();
@@ -423,6 +423,7 @@ ReturnedValue QmlContextWrapper::qmlSingletonWrapper(const StringRef &name)
     Q_ASSERT(r.isValid());
     Q_ASSERT(r.type);
     Q_ASSERT(r.type->isSingleton());
+    Q_ASSERT(v8);
 
     QQmlEngine *e = v8->engine();
     QQmlType::SingletonInstanceInfo *siinfo = r.type->singletonInstanceInfo();
diff --git a/src/qml/qml/qqmlcontextwrapper_p.h b/src/qml/qml/qqmlcontextwrapper_p.h
index 0ecec93652..3facf71aa0 100644
--- a/src/qml/qml/qqmlcontextwrapper_p.h
+++ b/src/qml/qml/qqmlcontextwrapper_p.h
@@ -97,9 +97,8 @@ struct Q_QML_EXPORT QmlContextWrapper : Object
     static void registerQmlDependencies(ExecutionEngine *context, const CompiledData::Function *compiledFunction);
 
     ReturnedValue idObjectsArray();
-    ReturnedValue qmlSingletonWrapper(const StringRef &name);
+    ReturnedValue qmlSingletonWrapper(QV8Engine *e, const StringRef &name);
 
-    QV8Engine *v8; // ### temporary, remove
     bool readOnly;
     bool ownsContext;
     bool isNullWrapper;
diff --git a/src/qml/qml/qqmlobjectcreator.cpp b/src/qml/qml/qqmlobjectcreator.cpp
index 7085915faa..32f3fe73fa 100644
--- a/src/qml/qml/qqmlobjectcreator.cpp
+++ b/src/qml/qml/qqmlobjectcreator.cpp
@@ -743,7 +743,7 @@ bool QQmlObjectCreator::setPropertyBinding(QQmlPropertyData *property, const QV4
         QV4::Function *runtimeFunction = compiledData->compilationUnit->runtimeFunctions[binding->value.compiledScriptIndex];
 
         QV4::Scope scope(_qmlContext);
-        QV4::ScopedFunctionObject function(scope, QV4::FunctionObject::creatScriptFunction(_qmlContext, runtimeFunction));
+        QV4::ScopedFunctionObject function(scope, QV4::FunctionObject::creatScriptFunction(_qmlContext, runtimeFunction, /*createProto*/ false));
 
         if (binding->flags & QV4::CompiledData::Binding::IsSignalHandlerExpression) {
             int signalIndex = _propertyCache->methodIndexToSignalIndex(property->coreIndex);
diff --git a/src/qml/qml/qqmlvme.cpp b/src/qml/qml/qqmlvme.cpp
index ce4997fef9..83c1f6595c 100644
--- a/src/qml/qml/qqmlvme.cpp
+++ b/src/qml/qml/qqmlvme.cpp
@@ -800,7 +800,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
 
             QV4::Function *runtimeFunction = COMP->compilationUnit->runtimeFunctions[instr.runtimeFunctionIndex];
 
-            tmpValue = QV4::FunctionObject::creatScriptFunction(qmlContext, runtimeFunction);
+            tmpValue = QV4::FunctionObject::creatScriptFunction(qmlContext, runtimeFunction, /*createProto*/ false);
 
             QQmlBoundSignal *bs = new QQmlBoundSignal(target, instr.signalIndex, target, engine);
             QQmlBoundSignalExpression *expr =
@@ -862,7 +862,7 @@ QObject *QQmlVME::run(QList<QQmlError> *errors,
 
             QV4::Function *runtimeFunction = COMP->compilationUnit->runtimeFunctions[instr.functionIndex];
 
-            tmpValue = QV4::FunctionObject::creatScriptFunction(qmlContext, runtimeFunction);
+            tmpValue = QV4::FunctionObject::creatScriptFunction(qmlContext, runtimeFunction, /*createProto*/ false);
 
             QQmlBinding *bind = new QQmlBinding(tmpValue, context, CTXT, COMP->name, instr.line, instr.column);
             bindValues.push(bind);