Move exceptionValue and globalObject from the Engine onto the JS stack

We'll need to move all GC'ed objects currently stored in ExecutionEngine
onto the JS stack for easier management in a new garbage collection
scheme. This is the start of that change.

Change-Id: Ib3ad8e846875dade8a807ea79f063173d40e4aad
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

20 files changed, 95 insertions, 99 deletions

diff --git a/src/qml/jsapi/qjsengine.cpp b/src/qml/jsapi/qjsengine.cpp
index 4db73c49f6..198c3c2b28 100644
--- a/src/qml/jsapi/qjsengine.cpp
+++ b/src/qml/jsapi/qjsengine.cpp
@@ -271,7 +271,7 @@ void QJSEngine::installTranslatorFunctions(const QJSValue &object)
     if (val)
         obj = val;
     if (!obj)
-        obj = scope.engine->globalObject();
+        obj = scope.engine->globalObject;
 #ifndef QT_NO_TRANSLATION
     obj->defineDefaultProperty(QStringLiteral("qsTranslate"), QV4::GlobalExtensions::method_qsTranslate);
     obj->defineDefaultProperty(QStringLiteral("QT_TRANSLATE_NOOP"), QV4::GlobalExtensions::method_qsTranslateNoOp);
@@ -414,7 +414,7 @@ QJSValue QJSEngine::globalObject() const
 {
     Q_D(const QJSEngine);
     QV4::Scope scope(d->m_v4Engine);
-    QV4::ScopedValue v(scope, d->m_v4Engine->globalObject());
+    QV4::ScopedValue v(scope, d->m_v4Engine->globalObject);
     return QJSValue(d->m_v4Engine, v->asReturnedValue());
 }
 
diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index 15dd1028d5..a9333ed8a9 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -637,7 +637,7 @@ QJSValue QJSValue::call(const QJSValueList &args)
 
     Scope scope(engine);
     ScopedCallData callData(scope, args.length());
-    callData->thisObject = engine->globalObject()->asReturnedValue();
+    callData->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");
diff --git a/src/qml/jsruntime/qv4context.cpp b/src/qml/jsruntime/qv4context.cpp
index 11bfa62afc..0951015dde 100644
--- a/src/qml/jsruntime/qv4context.cpp
+++ b/src/qml/jsruntime/qv4context.cpp
@@ -106,7 +106,7 @@ void ExecutionContext::createMutableBinding(String *name, bool deletable)
     Scope scope(this);
 
     // find the right context to create the binding on
-    ScopedObject activation(scope, d()->engine->globalObject());
+    ScopedObject activation(scope, d()->engine->globalObject);
     ScopedContext ctx(scope, this);
     while (ctx) {
         if (ctx->d()->type >= Heap::ExecutionContext::Type_CallContext) {
@@ -131,7 +131,7 @@ void ExecutionContext::createMutableBinding(String *name, bool deletable)
 Heap::GlobalContext::GlobalContext(ExecutionEngine *eng)
     : Heap::ExecutionContext(eng, Heap::ExecutionContext::Type_GlobalContext)
 {
-    global = eng->globalObject()->d();
+    global = eng->globalObject->d();
 }
 
 Heap::WithContext::WithContext(ExecutionEngine *engine, QV4::Object *with)
@@ -333,7 +333,7 @@ void ExecutionContext::setProperty(String *name, const Value &value)
         engine()->throwReferenceError(n);
         return;
     }
-    d()->engine->globalObject()->put(name, value);
+    d()->engine->globalObject->put(name, value);
 }
 
 ReturnedValue ExecutionContext::getProperty(String *name)
diff --git a/src/qml/jsruntime/qv4debugging.cpp b/src/qml/jsruntime/qv4debugging.cpp
index b72219cde9..cd9e1e3936 100644
--- a/src/qml/jsruntime/qv4debugging.cpp
+++ b/src/qml/jsruntime/qv4debugging.cpp
@@ -470,7 +470,7 @@ void Debugger::collectThrownValue(Collector *collector)
         void run()
         {
             Scope scope(engine);
-            ScopedValue v(scope, engine->exceptionValue);
+            ScopedValue v(scope, *engine->exceptionValue);
             collector->collect(QStringLiteral("exception"), v);
         }
     };
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 34186da94f..b05b080fd8 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -184,6 +184,7 @@ QQmlEngine *ExecutionEngine::qmlEngine() const
 
 ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     : current(0)
+    , hasException(false)
     , memoryManager(new QV4::MemoryManager(this))
     , executableAllocator(new QV4::ExecutableAllocator)
     , regExpAllocator(new QV4::ExecutableAllocator)
@@ -202,9 +203,6 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
 {
     MemoryManager::GCBlocker gcBlocker(memoryManager);
 
-    exceptionValue = Encode::undefined();
-    hasException = false;
-
     if (!factory) {
 
 #ifdef V4_ENABLE_JIT
@@ -228,6 +226,9 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     jsStackBase = (Value *)jsStack->base();
     jsStackTop = jsStackBase;
 
+    exceptionValue = jsAlloca(1);
+    globalObject = static_cast<Object *>(jsAlloca(1));
+
 #ifdef V4_USE_VALGRIND
     VALGRIND_MAKE_MEM_UNDEFINED(jsStackBase, 2*JSStackLimit);
 #endif
@@ -238,8 +239,6 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     if (!recheckCStackLimits())
         qFatal("Fatal: Not enough stack space available for QML. Please increase the process stack size to more than %d KBytes.", MinimumStackSize);
 
-    Scope scope(this);
-
     identifierTable = new IdentifierTable(this);
 
     classPool = new InternalClassPool;
@@ -293,8 +292,8 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     strictArgumentsObjectClass = argsClass->addMember(id_callee, Attr_Accessor|Attr_NotConfigurable|Attr_NotEnumerable);
     strictArgumentsObjectClass = strictArgumentsObjectClass->addMember(id_caller, Attr_Accessor|Attr_NotConfigurable|Attr_NotEnumerable);
 
-    m_globalObject = newObject();
-    Q_ASSERT(globalObject()->d()->vtable);
+    *static_cast<Value *>(globalObject) = newObject();
+    Q_ASSERT(globalObject->d()->vtable);
     initRootContext();
 
     stringPrototype = memoryManager->alloc<StringPrototype>(emptyClass, objectPrototype.as<Object>());
@@ -332,6 +331,7 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     variantPrototype = memoryManager->alloc<VariantPrototype>(emptyClass, objectPrototype.as<Object>());
     Q_ASSERT(variantPrototype.as<Object>()->prototype() == objectPrototype.as<Object>()->d());
 
+    Scope scope(this);
     sequencePrototype = ScopedValue(scope, memoryManager->alloc<SequencePrototype>(arrayClass, arrayPrototype.as<Object>()));
 
     ScopedContext global(scope, rootContext());
@@ -390,53 +390,53 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     //
     // set up the global object
     //
-    rootContext()->global = globalObject()->d();
-    rootContext()->callData->thisObject = globalObject();
-    Q_ASSERT(globalObject()->d()->vtable);
-
-    globalObject()->defineDefaultProperty(QStringLiteral("Object"), objectCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("String"), stringCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Number"), numberCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Boolean"), booleanCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Array"), arrayCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Function"), functionCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Date"), dateCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("RegExp"), regExpCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("Error"), errorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("EvalError"), evalErrorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("RangeError"), rangeErrorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("ReferenceError"), referenceErrorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("SyntaxError"), syntaxErrorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("TypeError"), typeErrorCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("URIError"), uRIErrorCtor);
-
-    globalObject()->defineDefaultProperty(QStringLiteral("ArrayBuffer"), arrayBufferCtor);
-    globalObject()->defineDefaultProperty(QStringLiteral("DataView"), dataViewCtor);
+    rootContext()->global = globalObject->d();
+    rootContext()->callData->thisObject = globalObject;
+    Q_ASSERT(globalObject->d()->vtable);
+
+    globalObject->defineDefaultProperty(QStringLiteral("Object"), objectCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("String"), stringCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Number"), numberCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Boolean"), booleanCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Array"), arrayCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Function"), functionCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Date"), dateCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("RegExp"), regExpCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("Error"), errorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("EvalError"), evalErrorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("RangeError"), rangeErrorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("ReferenceError"), referenceErrorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("SyntaxError"), syntaxErrorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("TypeError"), typeErrorCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("URIError"), uRIErrorCtor);
+
+    globalObject->defineDefaultProperty(QStringLiteral("ArrayBuffer"), arrayBufferCtor);
+    globalObject->defineDefaultProperty(QStringLiteral("DataView"), dataViewCtor);
     ScopedString str(scope);
     for (int i = 0; i < Heap::TypedArray::NTypes; ++i)
-        globalObject()->defineDefaultProperty((str = typedArrayCtors[i].as<FunctionObject>()->name())->toQString(), typedArrayCtors[i]);
+        globalObject->defineDefaultProperty((str = typedArrayCtors[i].as<FunctionObject>()->name())->toQString(), typedArrayCtors[i]);
     ScopedObject o(scope);
-    globalObject()->defineDefaultProperty(QStringLiteral("Math"), (o = memoryManager->alloc<MathObject>(this)));
-    globalObject()->defineDefaultProperty(QStringLiteral("JSON"), (o = memoryManager->alloc<JsonObject>(this)));
+    globalObject->defineDefaultProperty(QStringLiteral("Math"), (o = memoryManager->alloc<MathObject>(this)));
+    globalObject->defineDefaultProperty(QStringLiteral("JSON"), (o = memoryManager->alloc<JsonObject>(this)));
 
-    globalObject()->defineReadonlyProperty(QStringLiteral("undefined"), Primitive::undefinedValue());
-    globalObject()->defineReadonlyProperty(QStringLiteral("NaN"), Primitive::fromDouble(std::numeric_limits<double>::quiet_NaN()));
-    globalObject()->defineReadonlyProperty(QStringLiteral("Infinity"), Primitive::fromDouble(Q_INFINITY));
+    globalObject->defineReadonlyProperty(QStringLiteral("undefined"), Primitive::undefinedValue());
+    globalObject->defineReadonlyProperty(QStringLiteral("NaN"), Primitive::fromDouble(std::numeric_limits<double>::quiet_NaN()));
+    globalObject->defineReadonlyProperty(QStringLiteral("Infinity"), Primitive::fromDouble(Q_INFINITY));
 
 
     evalFunction = memoryManager->alloc<EvalFunction>(global);
-    globalObject()->defineDefaultProperty(QStringLiteral("eval"), (o = evalFunction));
-
-    globalObject()->defineDefaultProperty(QStringLiteral("parseInt"), GlobalFunctions::method_parseInt, 2);
-    globalObject()->defineDefaultProperty(QStringLiteral("parseFloat"), GlobalFunctions::method_parseFloat, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("isNaN"), GlobalFunctions::method_isNaN, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("isFinite"), GlobalFunctions::method_isFinite, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("decodeURI"), GlobalFunctions::method_decodeURI, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("decodeURIComponent"), GlobalFunctions::method_decodeURIComponent, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("encodeURI"), GlobalFunctions::method_encodeURI, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("encodeURIComponent"), GlobalFunctions::method_encodeURIComponent, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("escape"), GlobalFunctions::method_escape, 1);
-    globalObject()->defineDefaultProperty(QStringLiteral("unescape"), GlobalFunctions::method_unescape, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("eval"), (o = evalFunction));
+
+    globalObject->defineDefaultProperty(QStringLiteral("parseInt"), GlobalFunctions::method_parseInt, 2);
+    globalObject->defineDefaultProperty(QStringLiteral("parseFloat"), GlobalFunctions::method_parseFloat, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("isNaN"), GlobalFunctions::method_isNaN, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("isFinite"), GlobalFunctions::method_isFinite, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("decodeURI"), GlobalFunctions::method_decodeURI, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("decodeURIComponent"), GlobalFunctions::method_decodeURIComponent, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("encodeURI"), GlobalFunctions::method_encodeURI, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("encodeURIComponent"), GlobalFunctions::method_encodeURIComponent, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("escape"), GlobalFunctions::method_escape, 1);
+    globalObject->defineDefaultProperty(QStringLiteral("unescape"), GlobalFunctions::method_unescape, 1);
 
     ScopedString name(scope, newString(QStringLiteral("thrower")));
     thrower = BuiltinFunction::create(global, name, ::throwTypeError);
@@ -491,7 +491,7 @@ void ExecutionEngine::initRootContext()
     r->d()->callData = reinterpret_cast<CallData *>(r->d() + 1);
     r->d()->callData->tag = QV4::Value::_Integer_Type;
     r->d()->callData->argc = 0;
-    r->d()->callData->thisObject = globalObject();
+    r->d()->callData->thisObject = globalObject;
     r->d()->callData->args[0] = Encode::undefined();
 
     m_rootContext = r->d();
@@ -876,8 +876,6 @@ void ExecutionEngine::markObjects()
 {
     identifierTable->mark(this);
 
-    globalObject()->mark(this);
-
     for (int i = 0; i < nArgumentsAccessors; ++i) {
         const Property &pd = argumentsAccessors[i];
         if (Heap::FunctionObject *getter = pd.getter())
@@ -976,8 +974,6 @@ void ExecutionEngine::markObjects()
     for (int i = 0; i < Heap::TypedArray::NTypes; ++i)
         typedArrayPrototype[i].mark(this);
 
-    exceptionValue.mark(this);
-
     thrower->mark(this);
 
     if (m_qmlExtensions)
@@ -1007,7 +1003,7 @@ ReturnedValue ExecutionEngine::throwError(const Value &value)
         return Encode::undefined();
 
     hasException = true;
-    exceptionValue = value;
+    *exceptionValue = value;
     QV4::Scope scope(this);
     QV4::Scoped<ErrorObject> error(scope, value);
     if (!!error)
@@ -1028,8 +1024,8 @@ ReturnedValue ExecutionEngine::catchException(StackTrace *trace)
         *trace = exceptionStackTrace;
     exceptionStackTrace.clear();
     hasException = false;
-    ReturnedValue res = exceptionValue.asReturnedValue();
-    exceptionValue = Primitive::emptyValue();
+    ReturnedValue res = exceptionValue->asReturnedValue();
+    *exceptionValue = Primitive::emptyValue();
     return res;
 }
 
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index df68e3befa..a6a05c0483 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -108,14 +108,19 @@ public:
         --jsStackTop;
         return jsStackTop->heapObject();
     }
+    Value *jsAlloca(int nValues) {
+        Value *ptr = jsStackTop;
+        jsStackTop = ptr + nValues;
+        memset(ptr, 0, nValues*sizeof(Value));
+        return ptr;
+    }
 
     IdentifierTable *identifierTable;
 
     QV4::Debugging::Debugger *debugger;
     QV4::Profiling::Profiler *profiler;
 
-    Value m_globalObject;
-    Object *globalObject() { return reinterpret_cast<Object *>(&m_globalObject); }
+    Object *globalObject;
 
     Function *globalCode;
 
@@ -312,7 +317,7 @@ public:
     bool recheckCStackLimits();
 
     // Exception handling
-    Value exceptionValue;
+    Value *exceptionValue;
     StackTrace exceptionStackTrace;
 
     ReturnedValue throwError(const Value &value);
diff --git a/src/qml/jsruntime/qv4include.cpp b/src/qml/jsruntime/qv4include.cpp
index ed7ace9ed1..9bbcc0e21b 100644
--- a/src/qml/jsruntime/qv4include.cpp
+++ b/src/qml/jsruntime/qv4include.cpp
@@ -101,7 +101,7 @@ void QV4Include::callback(const QV4::Value &callback, const QV4::Value &status)
         return;
 
     QV4::ScopedCallData callData(scope, 1);
-    callData->thisObject = v4->globalObject()->asReturnedValue();
+    callData->thisObject = v4->globalObject->asReturnedValue();
     callData->args[0] = status;
     f->call(callData);
     if (scope.hasException())
diff --git a/src/qml/jsruntime/qv4lookup.cpp b/src/qml/jsruntime/qv4lookup.cpp
index f09b87414d..c75309a30b 100644
--- a/src/qml/jsruntime/qv4lookup.cpp
+++ b/src/qml/jsruntime/qv4lookup.cpp
@@ -580,7 +580,7 @@ ReturnedValue Lookup::arrayLengthGetter(Lookup *l, ExecutionEngine *engine, cons
 
 ReturnedValue Lookup::globalGetterGeneric(Lookup *l, ExecutionEngine *engine)
 {
-    Object *o = engine->globalObject();
+    Object *o = engine->globalObject;
     PropertyAttributes attrs;
     ReturnedValue v = l->lookup(o, &attrs);
     if (v != Primitive::emptyValue().asReturnedValue()) {
@@ -609,7 +609,7 @@ ReturnedValue Lookup::globalGetterGeneric(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetter0(Lookup *l, ExecutionEngine *engine)
 {
-    Object *o = engine->globalObject();
+    Object *o = engine->globalObject;
     if (l->classList[0] == o->internalClass())
         return o->memberData()->data[l->index].asReturnedValue();
 
@@ -619,7 +619,7 @@ ReturnedValue Lookup::globalGetter0(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetter1(Lookup *l, ExecutionEngine *engine)
 {
-    Object *o = engine->globalObject();
+    Object *o = engine->globalObject;
     if (l->classList[0] == o->internalClass() &&
         l->classList[1] == o->prototype()->internalClass)
         return o->prototype()->memberData->data[l->index].asReturnedValue();
@@ -630,7 +630,7 @@ ReturnedValue Lookup::globalGetter1(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetter2(Lookup *l, ExecutionEngine *engine)
 {
-    Heap::Object *o = engine->globalObject()->d();
+    Heap::Object *o = engine->globalObject->d();
     if (l->classList[0] == o->internalClass) {
         o = o->prototype;
         if (l->classList[1] == o->internalClass) {
@@ -646,7 +646,7 @@ ReturnedValue Lookup::globalGetter2(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetterAccessor0(Lookup *l, ExecutionEngine *engine)
 {
-    Object *o = engine->globalObject();
+    Object *o = engine->globalObject;
     if (l->classList[0] == o->internalClass()) {
         Scope scope(o->engine());
         ScopedFunctionObject getter(scope, o->propertyAt(l->index)->getter());
@@ -663,7 +663,7 @@ ReturnedValue Lookup::globalGetterAccessor0(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetterAccessor1(Lookup *l, ExecutionEngine *engine)
 {
-    Object *o = engine->globalObject();
+    Object *o = engine->globalObject;
     if (l->classList[0] == o->internalClass() &&
         l->classList[1] == o->prototype()->internalClass) {
         Scope scope(o->engine());
@@ -681,7 +681,7 @@ ReturnedValue Lookup::globalGetterAccessor1(Lookup *l, ExecutionEngine *engine)
 
 ReturnedValue Lookup::globalGetterAccessor2(Lookup *l, ExecutionEngine *engine)
 {
-    Heap::Object *o = engine->globalObject()->d();
+    Heap::Object *o = engine->globalObject->d();
     if (l->classList[0] == o->internalClass) {
         o = o->prototype;
         if (l->classList[1] == o->internalClass) {
diff --git a/src/qml/jsruntime/qv4objectproto.cpp b/src/qml/jsruntime/qv4objectproto.cpp
index 582c48b9cd..bac5da709e 100644
--- a/src/qml/jsruntime/qv4objectproto.cpp
+++ b/src/qml/jsruntime/qv4objectproto.cpp
@@ -485,7 +485,7 @@ ReturnedValue ObjectPrototype::method_defineGetter(CallContext *ctx)
     if (!o) {
         if (!ctx->thisObject().isUndefined())
             return Encode::undefined();
-        o = ctx->d()->engine->globalObject();
+        o = ctx->d()->engine->globalObject;
     }
 
     ScopedProperty pd(scope);
@@ -513,7 +513,7 @@ ReturnedValue ObjectPrototype::method_defineSetter(CallContext *ctx)
     if (!o) {
         if (!ctx->thisObject().isUndefined())
             return Encode::undefined();
-        o = ctx->d()->engine->globalObject();
+        o = ctx->d()->engine->globalObject;
     }
 
     ScopedProperty pd(scope);
diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index a7810563c9..d8c8cbe42c 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -802,7 +802,7 @@ struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
             QV4::ScopedFunctionObject f(scope, This->function.value());
 
             QV4::ScopedCallData callData(scope, argCount);
-            callData->thisObject = This->thisObject.isUndefined() ? v4->globalObject()->asReturnedValue() : This->thisObject.value();
+            callData->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>()) {
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index ae618ceb6e..bff9eaf927 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -1426,7 +1426,7 @@ void Runtime::convertThisToObject(ExecutionEngine *engine)
     if (t->isObject())
         return;
     if (t->isNullOrUndefined()) {
-        *t = engine->globalObject()->asReturnedValue();
+        *t = engine->globalObject->asReturnedValue();
     } else {
         *t = t->toObject(engine)->asReturnedValue();
     }
diff --git a/src/qml/jsruntime/qv4scopedvalue_p.h b/src/qml/jsruntime/qv4scopedvalue_p.h
index b469567866..98ced91b05 100644
--- a/src/qml/jsruntime/qv4scopedvalue_p.h
+++ b/src/qml/jsruntime/qv4scopedvalue_p.h
@@ -85,10 +85,7 @@ struct Scope {
 #ifndef QT_NO_DEBUG
         size += nValues;
 #endif
-        Value *ptr = engine->jsStackTop;
-        engine->jsStackTop = ptr + nValues;
-        memset(ptr, 0, nValues*sizeof(Value));
-        return ptr;
+        return engine->jsAlloca(nValues);
     }
 
     bool hasException() const {
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index 79bd1db6c0..1d16900b78 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -400,7 +400,7 @@ public:
             ScopedCallData callData(scope, 2);
             callData->args[0] = convertElementToValue(this->m_ctx->d()->engine, lhs);
             callData->args[1] = convertElementToValue(this->m_ctx->d()->engine, rhs);
-            callData->thisObject = this->m_ctx->d()->engine->globalObject();
+            callData->thisObject = this->m_ctx->d()->engine->globalObject;
             QV4::ScopedValue result(scope, compare->call(callData));
             return result->toNumber() < 0;
         }
diff --git a/src/qml/qml/qqmlcomponent.cpp b/src/qml/qml/qqmlcomponent.cpp
index 881726c00f..8795d6d07a 100644
--- a/src/qml/qml/qqmlcomponent.cpp
+++ b/src/qml/qml/qqmlcomponent.cpp
@@ -1244,7 +1244,7 @@ void QQmlComponent::createObject(QQmlV4Function *args)
         QV4::ScopedValue f(scope, QV4::Script::evaluate(v4, QString::fromLatin1(INITIALPROPERTIES_SOURCE), qmlglobal));
         Q_ASSERT(f->as<QV4::FunctionObject>());
         QV4::ScopedCallData callData(scope, 2);
-        callData->thisObject = v4->globalObject();
+        callData->thisObject = v4->globalObject;
         callData->args[0] = object;
         callData->args[1] = valuemap;
         f->as<QV4::FunctionObject>()->call(callData);
@@ -1397,7 +1397,7 @@ void QQmlComponentPrivate::initializeObjectWithInitialProperties(const QV4::Valu
         QV4::ScopedFunctionObject f(scope, QV4::Script::evaluate(v4engine,
                                                                  QString::fromLatin1(INITIALPROPERTIES_SOURCE), qmlGlobalObj));
         QV4::ScopedCallData callData(scope, 2);
-        callData->thisObject = v4engine->globalObject();
+        callData->thisObject = v4engine->globalObject;
         callData->args[0] = object;
         callData->args[1] = valuemap;
         f->call(callData);
@@ -1494,7 +1494,7 @@ void QV4::QmlIncubatorObject::setInitialState(QObject *o)
 
         QV4::ScopedFunctionObject f(scope, QV4::Script::evaluate(v4, QString::fromLatin1(INITIALPROPERTIES_SOURCE), d()->qmlGlobal.as<Object>()));
         QV4::ScopedCallData callData(scope, 2);
-        callData->thisObject = v4->globalObject();
+        callData->thisObject = v4->globalObject;
         callData->args[0] = QV4::QObjectWrapper::wrap(v4, o);
         callData->args[1] = d()->valuemap;
         f->call(callData);
diff --git a/src/qml/qml/qqmlcontextwrapper.cpp b/src/qml/qml/qqmlcontextwrapper.cpp
index 453531376f..9b921b9fad 100644
--- a/src/qml/qml/qqmlcontextwrapper.cpp
+++ b/src/qml/qml/qqmlcontextwrapper.cpp
@@ -135,7 +135,7 @@ ReturnedValue QmlContextWrapper::get(const Managed *m, String *name, bool *hasPr
     // In V8 the JS global object would come _before_ the QML global object,
     // so simulate that here.
     bool hasProp;
-    QV4::ScopedValue result(scope, v4->globalObject()->get(name, &hasProp));
+    QV4::ScopedValue result(scope, v4->globalObject->get(name, &hasProp));
     if (hasProp) {
         if (hasProperty)
             *hasProperty = hasProp;
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index 2e1c108a5e..b353e77474 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -148,7 +148,7 @@ QV4::ReturnedValue QQmlJavaScriptExpression::evaluate(QQmlContextData *context,
     QV4::ExecutionEngine *v4 = QV8Engine::getV4(ep->v8engine());
     QV4::Scope scope(v4);
     QV4::ScopedValue result(scope, QV4::Primitive::undefinedValue());
-    callData->thisObject = v4->globalObject();
+    callData->thisObject = v4->globalObject;
     if (scopeObject()) {
         QV4::ScopedValue value(scope, QV4::QObjectWrapper::wrap(v4, scopeObject()));
         if (value->isObject())
diff --git a/src/qml/qml/qqmlxmlhttprequest.cpp b/src/qml/qml/qqmlxmlhttprequest.cpp
index 6789d1ed1a..b526775640 100644
--- a/src/qml/qml/qqmlxmlhttprequest.cpp
+++ b/src/qml/qml/qqmlxmlhttprequest.cpp
@@ -2058,7 +2058,7 @@ void *qt_add_qmlxmlhttprequest(ExecutionEngine *v4)
 
     Scoped<QQmlXMLHttpRequestCtor> ctor(scope, v4->memoryManager->alloc<QQmlXMLHttpRequestCtor>(v4));
     ScopedString s(scope, v4->newString(QStringLiteral("XMLHttpRequest")));
-    v4->globalObject()->defineReadonlyProperty(s, ctor);
+    v4->globalObject->defineReadonlyProperty(s, ctor);
 
     QQmlXMLHttpRequestData *data = new QQmlXMLHttpRequestData;
     return data;
diff --git a/src/qml/qml/v8/qv4domerrors.cpp b/src/qml/qml/v8/qv4domerrors.cpp
index c318e2e550..1baaa113aa 100644
--- a/src/qml/qml/v8/qv4domerrors.cpp
+++ b/src/qml/qml/v8/qv4domerrors.cpp
@@ -59,7 +59,7 @@ void qt_add_domexceptions(ExecutionEngine *e)
     domexception->defineReadonlyProperty(QStringLiteral("INVALID_ACCESS_ERR"), Primitive::fromInt32(DOMEXCEPTION_INVALID_ACCESS_ERR));
     domexception->defineReadonlyProperty(QStringLiteral("VALIDATION_ERR"), Primitive::fromInt32(DOMEXCEPTION_VALIDATION_ERR));
     domexception->defineReadonlyProperty(QStringLiteral("TYPE_MISMATCH_ERR"), Primitive::fromInt32(DOMEXCEPTION_TYPE_MISMATCH_ERR));
-    e->globalObject()->defineDefaultProperty(QStringLiteral("DOMException"), domexception);
+    e->globalObject->defineDefaultProperty(QStringLiteral("DOMException"), domexception);
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/v8/qv4sqlerrors.cpp b/src/qml/qml/v8/qv4sqlerrors.cpp
index b7a5b71540..c61e57560d 100644
--- a/src/qml/qml/v8/qv4sqlerrors.cpp
+++ b/src/qml/qml/v8/qv4sqlerrors.cpp
@@ -51,7 +51,7 @@ void qt_add_sqlexceptions(QV4::ExecutionEngine *engine)
     sqlexception->defineReadonlyProperty(QStringLiteral("SYNTAX_ERR"), Primitive::fromInt32(SQLEXCEPTION_SYNTAX_ERR));
     sqlexception->defineReadonlyProperty(QStringLiteral("CONSTRAINT_ERR"), Primitive::fromInt32(SQLEXCEPTION_CONSTRAINT_ERR));
     sqlexception->defineReadonlyProperty(QStringLiteral("TIMEOUT_ERR"), Primitive::fromInt32(SQLEXCEPTION_TIMEOUT_ERR));
-    engine->globalObject()->defineDefaultProperty(QStringLiteral("SQLException"), sqlexception);
+    engine->globalObject->defineDefaultProperty(QStringLiteral("SQLException"), sqlexception);
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index 54627a16a4..be28b948f5 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -179,7 +179,7 @@ QQmlContextData *QV8Engine::callingContext()
 void QV8Engine::initializeGlobal()
 {
     QV4::Scope scope(m_v4Engine);
-    QV4::GlobalExtensions::init(m_engine, m_v4Engine->globalObject());
+    QV4::GlobalExtensions::init(m_engine, m_v4Engine->globalObject);
 
     QQmlLocale::registerStringLocaleCompare(m_v4Engine);
     QQmlDateExtension::registerExtension(m_v4Engine);
@@ -191,9 +191,9 @@ void QV8Engine::initializeGlobal()
     qt_add_sqlexceptions(m_v4Engine);
 
     {
-        for (uint i = 0; i < m_v4Engine->globalObject()->internalClass()->size; ++i) {
-            if (m_v4Engine->globalObject()->internalClass()->nameMap.at(i))
-                m_illegalNames.insert(m_v4Engine->globalObject()->internalClass()->nameMap.at(i)->string);
+        for (uint i = 0; i < m_v4Engine->globalObject->internalClass()->size; ++i) {
+            if (m_v4Engine->globalObject->internalClass()->nameMap.at(i))
+                m_illegalNames.insert(m_v4Engine->globalObject->internalClass()->nameMap.at(i)->string);
         }
     }
 
@@ -229,7 +229,7 @@ void QV8Engine::freezeObject(const QV4::Value &value)
     QV4::ScopedFunctionObject f(scope, m_freezeObject.value());
     QV4::ScopedCallData callData(scope, 1);
     callData->args[0] = value;
-    callData->thisObject = m_v4Engine->globalObject();
+    callData->thisObject = m_v4Engine->globalObject;
     f->call(callData);
 }
 
@@ -266,9 +266,7 @@ void QV8Engine::setExtensionData(int index, Deletable *data)
 void QV8Engine::initQmlGlobalObject()
 {
     initializeGlobal();
-    QV4::Scope scope(m_v4Engine);
-    QV4::ScopedValue v(scope, m_v4Engine->globalObject());
-    freezeObject(v);
+    freezeObject(*m_v4Engine->globalObject);
 }
 
 void QV8Engine::setEngine(QQmlEngine *engine)
@@ -279,7 +277,7 @@ void QV8Engine::setEngine(QQmlEngine *engine)
 
 QV4::ReturnedValue QV8Engine::global()
 {
-    return m_v4Engine->globalObject()->asReturnedValue();
+    return m_v4Engine->globalObject->asReturnedValue();
 }
 
 void QV8Engine::startTimer(const QString &timerName)