Speed up QQmlEngine constructor

Freezing the global object using a script is pretty slow,
esp. given that the script needs to be compiled as well. Rather
do it programmatically.

The old code actually had a bug that would only cause the global
object to be frozen, not it's children. The new code fixes this,
but doesn't completely freeze the objects. Instead it makes all
the existing properties of the global object and it's children
readonly, but still allows extending existing objects with new
properties.

Change-Id: I0d7331cdc89a0ac717b8ed3b1a490b2a3742de02
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 34 insertions, 28 deletions

diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index 6cb316ce9f..effc37a0eb 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -191,41 +191,47 @@ void QV8Engine::initializeGlobal()
                 m_illegalNames.insert(m_v4Engine->globalObject->internalClass()->nameMap.at(i)->string);
         }
     }
+}
 
-    {
-#define FREEZE_SOURCE "(function freeze_recur(obj) { "\
-                      "    if (Qt.isQtObject(obj)) return;"\
-                      "    if (obj != Function.connect && obj != Function.disconnect && "\
-                      "        obj instanceof Object) {"\
-                      "        var properties = Object.getOwnPropertyNames(obj);"\
-                      "        for (var prop in properties) { "\
-                      "            if (prop == \"connect\" || prop == \"disconnect\") {"\
-                      "                Object.freeze(obj[prop]); "\
-                      "                continue;"\
-                      "            }"\
-                      "            freeze_recur(obj[prop]);"\
-                      "        }"\
-                      "    }"\
-                      "    if (obj instanceof Object) {"\
-                      "        Object.freeze(obj);"\
-                      "    }"\
-                      "})"
-
-        QV4::ScopedFunctionObject result(scope, QV4::Script::evaluate(m_v4Engine, QString::fromUtf8(FREEZE_SOURCE), 0));
-        Q_ASSERT(!!result);
-        m_freezeObject.set(scope.engine, result);
-#undef FREEZE_SOURCE
+static void freeze_recursive(QV4::ExecutionEngine *v4, QV4::Object *object)
+{
+    if (object->as<QV4::QObjectWrapper>())
+        return;
+
+    QV4::Scope scope(v4);
+
+    bool instanceOfObject = false;
+    QV4::ScopedObject p(scope, object->prototype());
+    while (p) {
+        if (p->d() == v4->objectPrototype()->d()) {
+            instanceOfObject = true;
+            break;
+        }
+        p = p->prototype();
+    }
+    if (!instanceOfObject)
+        return;
+
+    QV4::InternalClass *frozen = object->internalClass()->propertiesFrozen();
+    if (object->internalClass() == frozen)
+        return;
+    object->setInternalClass(frozen);
+
+    QV4::ScopedObject o(scope);
+    for (uint i = 0; i < frozen->size; ++i) {
+        if (!frozen->nameMap.at(i))
+            continue;
+        o = *object->propertyData(i);
+        if (o)
+            freeze_recursive(v4, o);
     }
 }
 
 void QV8Engine::freezeObject(const QV4::Value &value)
 {
     QV4::Scope scope(m_v4Engine);
-    QV4::ScopedFunctionObject f(scope, m_freezeObject.value());
-    QV4::ScopedCallData callData(scope, 1);
-    callData->args[0] = value;
-    callData->thisObject = m_v4Engine->globalObject;
-    f->call(callData);
+    QV4::ScopedObject o(scope, value);
+    freeze_recursive(m_v4Engine, o);
 }
 
 struct QV8EngineRegistrationData