Avoid calling out to public API in the QtScript implementation

There's no reason to construct QScriptValues when JSC::JSValues
can be operated on directly. A benchmark showed that ~10% of the
time for reading a QObject property from a script was spent just
creating and destroying QScriptValue temporaries. It's time to
finally get rid of this potential bottleneck, not just in the
QObject integration but everywhere.

This change refactors the code so that all internal operations
are performed on JSC::JSValue (most importantly, conversion
from/to Qt types), and the public API functions are just thin
wrappers around these. E.g. instead of doing

enginePrivate->scriptValueFromJSCValue(jsValue).toQObject()

the implementation now does

QScriptEnginePrivate::toQObject(jsValue)

Other operations are delegated to the engine implementation
in similar style.

Task-number: QTBUG-8304
Reviewed-by: Jedrzej Nowacki

4 files changed, 54 insertions, 72 deletions

diff --git a/src/script/bridge/qscriptclassobject.cpp b/src/script/bridge/qscriptclassobject.cpp
index a3dd239..ce0a08e 100644
--- a/src/script/bridge/qscriptclassobject.cpp
+++ b/src/script/bridge/qscriptclassobject.cpp
@@ -206,7 +206,7 @@ JSC::JSValue JSC_HOST_CALL ClassObjectDelegate::call(JSC::ExecState *exec, JSC::
     QVariant result = scriptClass->extension(QScriptClass::Callable, qVariantFromValue(ctx));
     eng_p->popContext();
     eng_p->currentFrame = oldFrame;
-    return eng_p->jscValueFromVariant(result);
+    return QScriptEnginePrivate::jscValueFromVariant(exec, result);
 }
 
 JSC::ConstructType ClassObjectDelegate::getConstructData(QScriptObject*, JSC::ConstructData &constructData)
diff --git a/src/script/bridge/qscriptdeclarativeclass.cpp b/src/script/bridge/qscriptdeclarativeclass.cpp
index ce2fc23..1d11ede 100644
--- a/src/script/bridge/qscriptdeclarativeclass.cpp
+++ b/src/script/bridge/qscriptdeclarativeclass.cpp
@@ -207,25 +207,17 @@ QScriptDeclarativeClass::newObjectValue(QScriptEngine *engine,
 QScriptDeclarativeClass *QScriptDeclarativeClass::scriptClass(const QScriptValue &v)
 {
     QScriptValuePrivate *d = QScriptValuePrivate::get(v);
-    if (!d || !d->isJSC() || !d->jscValue.inherits(&QScriptObject::info))
+    if (!d || !d->isJSC())
         return 0;
-    QScriptObject *scriptObject = static_cast<QScriptObject*>(JSC::asObject(d->jscValue));
-    QScriptObjectDelegate *delegate = scriptObject->delegate();
-    if (!delegate || (delegate->type() != QScriptObjectDelegate::DeclarativeClassObject))
-        return 0;
-    return static_cast<QScript::DeclarativeObjectDelegate*>(delegate)->scriptClass();
+    return QScriptEnginePrivate::declarativeClass(d->jscValue);
 }
 
 QScriptDeclarativeClass::Object *QScriptDeclarativeClass::object(const QScriptValue &v)
 {
     QScriptValuePrivate *d = QScriptValuePrivate::get(v);
-    if (!d || !d->isJSC() || !d->jscValue.inherits(&QScriptObject::info))
-        return 0;
-    QScriptObject *scriptObject = static_cast<QScriptObject*>(JSC::asObject(d->jscValue));
-    QScriptObjectDelegate *delegate = scriptObject->delegate();
-    if (!delegate || (delegate->type() != QScriptObjectDelegate::DeclarativeClassObject))
+    if (!d || !d->isJSC())
         return 0;
-    return static_cast<QScript::DeclarativeObjectDelegate*>(delegate)->object();
+    return QScriptEnginePrivate::declarativeObject(d->jscValue);
 }
 
 QScriptValue QScriptDeclarativeClass::function(const QScriptValue &v, const Identifier &name)
diff --git a/src/script/bridge/qscriptqobject.cpp b/src/script/bridge/qscriptqobject.cpp
index db312bc..30e5a26 100644
--- a/src/script/bridge/qscriptqobject.cpp
+++ b/src/script/bridge/qscriptqobject.cpp
@@ -169,17 +169,15 @@ static inline QByteArray methodName(const QMetaMethod &method)
     return signature.left(signature.indexOf('('));
 }
 
-static QVariant variantFromValue(QScriptEnginePrivate *eng,
-                                 int targetType, const QScriptValue &value)
+static QVariant variantFromValue(JSC::ExecState *exec, int targetType, JSC::JSValue value)
 {
     QVariant v(targetType, (void *)0);
-    Q_ASSERT(eng);
-    if (QScriptEnginePrivate::convert(value, targetType, v.data(), eng))
+    if (QScriptEnginePrivate::convertValue(exec, value, targetType, v.data()))
         return v;
     if (uint(targetType) == QVariant::LastType)
-        return value.toVariant();
-    if (value.isVariant()) {
-        v = value.toVariant();
+        return QScriptEnginePrivate::toVariant(exec, value);
+    if (QScriptEnginePrivate::isVariant(value)) {
+        v = QScriptEnginePrivate::variantValue(value);
         if (v.canConvert(QVariant::Type(targetType))) {
             v.convert(QVariant::Type(targetType));
             return v;
@@ -591,38 +589,38 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
         bool converted = true;
         int matchDistance = 0;
         for (int i = 0; converted && i < mtd.argumentCount(); ++i) {
-            QScriptValue actual;
+            JSC::JSValue actual;
             if (i < (int)scriptArgs.size())
-                actual = engine->scriptValueFromJSCValue(scriptArgs.at(i));
+                actual = scriptArgs.at(i);
             else
-                actual = QScriptValue(QScriptValue::UndefinedValue);
+                actual = JSC::jsUndefined();
             QScriptMetaType argType = mtd.argumentType(i);
             int tid = -1;
             QVariant v;
             if (argType.isUnresolved()) {
                 v = QVariant(QMetaType::QObjectStar, (void *)0);
-                converted = engine->convertToNativeQObject(
-                    actual, argType.name(), reinterpret_cast<void* *>(v.data()));
+                converted = QScriptEnginePrivate::convertToNativeQObject(
+                    exec, actual, argType.name(), reinterpret_cast<void* *>(v.data()));
             } else if (argType.isVariant()) {
-                if (actual.isVariant()) {
-                    v = actual.toVariant();
+                if (QScriptEnginePrivate::isVariant(actual)) {
+                    v = QScriptEnginePrivate::variantValue(actual);
                 } else {
-                    v = actual.toVariant();
+                    v = QScriptEnginePrivate::toVariant(exec, actual);
                     converted = v.isValid() || actual.isUndefined() || actual.isNull();
                 }
             } else {
                 tid = argType.typeId();
                 v = QVariant(tid, (void *)0);
-                converted = QScriptEnginePrivate::convert(actual, tid, v.data(), engine);
+                converted = QScriptEnginePrivate::convertValue(exec, actual, tid, v.data());
                 if (exec->hadException())
                     return exec->exception();
             }
 
             if (!converted) {
-                if (actual.isVariant()) {
+                if (QScriptEnginePrivate::isVariant(actual)) {
                     if (tid == -1)
                         tid = argType.typeId();
-                    QVariant vv = actual.toVariant();
+                    QVariant vv = QScriptEnginePrivate::variantValue(actual);
                     if (vv.canConvert(QVariant::Type(tid))) {
                         v = vv;
                         converted = v.convert(QVariant::Type(tid));
@@ -649,14 +647,14 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
                     }
                     if (m.isValid()) {
                         if (actual.isNumber()) {
-                            int ival = actual.toInt32();
+                            int ival = QScriptEnginePrivate::toInt32(exec, actual);
                             if (m.valueToKey(ival) != 0) {
                                 qVariantSetValue(v, ival);
                                 converted = true;
                                 matchDistance += 10;
                             }
                         } else {
-                            QString sval = actual.toString();
+                            QString sval = QScriptEnginePrivate::toString(exec, actual);
                             int ival = m.keyToValue(sval.toLatin1());
                             if (ival != -1) {
                                 qVariantSetValue(v, ival);
@@ -718,7 +716,7 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
                         matchDistance += 10;
                         break;
                     }
-                } else if (actual.isDate()) {
+                } else if (QScriptEnginePrivate::isDate(actual)) {
                     switch (tid) {
                     case QMetaType::QDateTime:
                         // perfect
@@ -733,7 +731,7 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
                         matchDistance += 10;
                         break;
                     }
-                } else if (actual.isRegExp()) {
+                } else if (QScriptEnginePrivate::isRegExp(actual)) {
                     switch (tid) {
                     case QMetaType::QRegExp:
                         // perfect
@@ -742,14 +740,14 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
                         matchDistance += 10;
                         break;
                     }
-                } else if (actual.isVariant()) {
+                } else if (QScriptEnginePrivate::isVariant(actual)) {
                     if (argType.isVariant()
-                        || (actual.toVariant().userType() == tid)) {
+                        || (QScriptEnginePrivate::toVariant(exec, actual).userType() == tid)) {
                         // perfect
                     } else {
                         matchDistance += 10;
                     }
-                } else if (actual.isArray()) {
+                } else if (QScriptEnginePrivate::isArray(actual)) {
                     switch (tid) {
                     case QMetaType::QStringList:
                     case QMetaType::QVariantList:
@@ -759,7 +757,7 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
                         matchDistance += 10;
                         break;
                     }
-                } else if (actual.isQObject()) {
+                } else if (QScriptEnginePrivate::isQObject(actual)) {
                     switch (tid) {
                     case QMetaType::QObjectStar:
                     case QMetaType::QWidgetStar:
@@ -953,13 +951,11 @@ static JSC::JSValue callQtMethod(JSC::ExecState *exec, QMetaMethod::MethodType c
             } else {
                 QScriptMetaType retType = chosenMethod.returnType();
                 if (retType.isVariant()) {
-                    result = engine->jscValueFromVariant(*(QVariant *)params[0]);
+                    result = QScriptEnginePrivate::jscValueFromVariant(exec, *(QVariant *)params[0]);
                 } else if (retType.typeId() != 0) {
-                    result = engine->scriptValueToJSCValue(engine->create(retType.typeId(), params[0]));
-                    if (!result) {
-                        QScriptValue sv = QScriptEnginePrivate::get(engine)->newVariant(QVariant(retType.typeId(), params[0]));
-                        result = engine->scriptValueToJSCValue(sv);
-                    }
+                    result = QScriptEnginePrivate::create(exec, retType.typeId(), params[0]);
+                    if (!result)
+                        result = engine->newVariant(QVariant(retType.typeId(), params[0]));
                 } else {
                     result = JSC::jsUndefined();
                 }
@@ -1065,15 +1061,13 @@ JSC::JSValue QtPropertyFunction::execute(JSC::ExecState *exec,
 {
     JSC::JSValue result = JSC::jsUndefined();
 
-    // ### don't go via QScriptValue
     QScriptEnginePrivate *engine = scriptEngineFromExec(exec);
     thisValue = engine->toUsableValue(thisValue);
-    QScriptValue object = engine->scriptValueFromJSCValue(thisValue);
-    QObject *qobject = object.toQObject();
+    QObject *qobject = QScriptEnginePrivate::toQObject(exec, thisValue);
     while ((!qobject || (qobject->metaObject() != data->meta))
-           && object.prototype().isObject()) {
-        object = object.prototype();
-        qobject = object.toQObject();
+        && JSC::asObject(thisValue)->prototype().isObject()) {
+        thisValue = JSC::asObject(thisValue)->prototype();
+        qobject = QScriptEnginePrivate::toQObject(exec, thisValue);
     }
     Q_ASSERT_X(qobject, Q_FUNC_INFO, "this-object must be a QObject");
 
@@ -1094,7 +1088,7 @@ JSC::JSValue QtPropertyFunction::execute(JSC::ExecState *exec,
             if (scriptable)
                 QScriptablePrivate::get(scriptable)->engine = oldEngine;
 
-            result = engine->jscValueFromVariant(v);
+            result = QScriptEnginePrivate::jscValueFromVariant(exec, v);
         }
     } else {
         // set
@@ -1106,9 +1100,7 @@ JSC::JSValue QtPropertyFunction::execute(JSC::ExecState *exec,
             // string to enum value
             v = (QString)arg.toString(exec);
         } else {
-            // ### don't go via QScriptValue
-            QScriptValue tmp = engine->scriptValueFromJSCValue(arg);
-            v = variantFromValue(engine, prop.userType(), tmp);
+            v = variantFromValue(exec, prop.userType(), arg);
         }
 
         QScriptable *scriptable = scriptableFromQObject(qobject);
@@ -1237,7 +1229,7 @@ bool QObjectDelegate::getOwnPropertySlot(QScriptObject *object, JSC::ExecState *
                     if (!prop.isValid())
                         val = JSC::jsUndefined();
                     else
-                        val = eng->jscValueFromVariant(prop.read(qobject));
+                        val = QScriptEnginePrivate::jscValueFromVariant(exec, prop.read(qobject));
                     slot.setValue(val);
                 }
                 return true;
@@ -1247,7 +1239,7 @@ bool QObjectDelegate::getOwnPropertySlot(QScriptObject *object, JSC::ExecState *
 
     index = qobject->dynamicPropertyNames().indexOf(name);
     if (index != -1) {
-        JSC::JSValue val = eng->jscValueFromVariant(qobject->property(name));
+        JSC::JSValue val = QScriptEnginePrivate::jscValueFromVariant(exec, qobject->property(name));
         slot.setValue(val);
         return true;
     }
@@ -1274,8 +1266,7 @@ bool QObjectDelegate::getOwnPropertySlot(QScriptObject *object, JSC::ExecState *
             QObject *child = children.at(index);
             if (child->objectName() == QString(propertyName.ustring())) {
                 QScriptEngine::QObjectWrapOptions opt = QScriptEngine::PreferExistingWrapperObject;
-                QScriptValue tmp = QScriptEnginePrivate::get(eng)->newQObject(child, QScriptEngine::QtOwnership, opt);
-                slot.setValue(eng->scriptValueToJSCValue(tmp));
+                slot.setValue(eng->newQObject(child, QScriptEngine::QtOwnership, opt));
                 return true;
             }
         }
@@ -1370,7 +1361,7 @@ bool QObjectDelegate::getOwnPropertyDescriptor(QScriptObject *object, JSC::ExecS
                     if (!prop.isValid())
                         val = JSC::jsUndefined();
                     else
-                        val = eng->jscValueFromVariant(prop.read(qobject));
+                        val = QScriptEnginePrivate::jscValueFromVariant(exec, prop.read(qobject));
                     descriptor.setDescriptor(val, attributes);
                 }
                 return true;
@@ -1380,7 +1371,7 @@ bool QObjectDelegate::getOwnPropertyDescriptor(QScriptObject *object, JSC::ExecS
 
     index = qobject->dynamicPropertyNames().indexOf(name);
     if (index != -1) {
-        JSC::JSValue val = eng->jscValueFromVariant(qobject->property(name));
+        JSC::JSValue val = QScriptEnginePrivate::jscValueFromVariant(exec, qobject->property(name));
         descriptor.setDescriptor(val, QObjectMemberAttribute);
         return true;
     }
@@ -1410,8 +1401,8 @@ bool QObjectDelegate::getOwnPropertyDescriptor(QScriptObject *object, JSC::ExecS
             QObject *child = children.at(index);
             if (child->objectName() == QString(propertyName.ustring())) {
                 QScriptEngine::QObjectWrapOptions opt = QScriptEngine::PreferExistingWrapperObject;
-                QScriptValue tmp = QScriptEnginePrivate::get(eng)->newQObject(child, QScriptEngine::QtOwnership, opt);
-                descriptor.setDescriptor(eng->scriptValueToJSCValue(tmp), JSC::ReadOnly | JSC::DontDelete | JSC::DontEnum);
+                descriptor.setDescriptor(eng->newQObject(child, QScriptEngine::QtOwnership, opt),
+                                         JSC::ReadOnly | JSC::DontDelete | JSC::DontEnum);
                 return true;
             }
         }
@@ -1490,7 +1481,7 @@ void QObjectDelegate::put(QScriptObject *object, JSC::ExecState* exec,
                         // string to enum value
                         v = (QString)value.toString(exec);
                     } else {
-                        v = eng->jscValueToVariant(value, prop.userType());
+                        v = QScriptEnginePrivate::jscValueToVariant(exec, value, prop.userType());
                     }
                     (void)prop.write(qobject, v);
                 }
@@ -1512,7 +1503,7 @@ void QObjectDelegate::put(QScriptObject *object, JSC::ExecState* exec,
 
     index = qobject->dynamicPropertyNames().indexOf(name);
     if ((index != -1) || (opt & QScriptEngine::AutoCreateDynamicProperties)) {
-        QVariant v = eng->scriptValueFromJSCValue(value).toVariant();
+        QVariant v = QScriptEnginePrivate::toVariant(exec, value);
         (void)qobject->setProperty(name, v);
         return;
     }
@@ -2178,24 +2169,23 @@ void QObjectConnectionManager::execute(int slotIndex, void **argv)
     JSC::ExecState *exec = engine->currentFrame;
     QVarLengthArray<JSC::JSValue, 8> argsVector(argc);
     for (int i = 0; i < argc; ++i) {
-        // ### optimize -- no need to convert via QScriptValue
-        QScriptValue actual;
+        JSC::JSValue actual;
         void *arg = argv[i + 1];
         QByteArray typeName = parameterTypes.at(i);
         int argType = QMetaType::type(parameterTypes.at(i));
         if (!argType) {
             if (typeName == "QVariant") {
-                actual = engine->scriptValueFromVariant(*reinterpret_cast<QVariant*>(arg));
+                actual = QScriptEnginePrivate::jscValueFromVariant(exec, *reinterpret_cast<QVariant*>(arg));
             } else {
                 qWarning("QScriptEngine: Unable to handle unregistered datatype '%s' "
                          "when invoking handler of signal %s::%s",
                          typeName.constData(), meta->className(), method.signature());
-                actual = QScriptValue(QScriptValue::UndefinedValue);
+                actual = JSC::jsUndefined();
             }
         } else {
-            actual = engine->create(argType, arg);
+            actual = QScriptEnginePrivate::create(exec, argType, arg);
         }
-        argsVector[i] = engine->scriptValueToJSCValue(actual);
+        argsVector[i] = actual;
     }
     JSC::ArgList jscArgs(argsVector.data(), argsVector.size());
 
diff --git a/src/script/bridge/qscriptvariant.cpp b/src/script/bridge/qscriptvariant.cpp
index 0287d24..b4f0365 100644
--- a/src/script/bridge/qscriptvariant.cpp
+++ b/src/script/bridge/qscriptvariant.cpp
@@ -133,7 +133,7 @@ static JSC::JSValue JSC_HOST_CALL variantProtoFuncToString(JSC::ExecState *exec,
 bool QVariantDelegate::compareToObject(QScriptObject *, JSC::ExecState *exec, JSC::JSObject *o2)
 {
     const QVariant &variant1 = value();
-    return variant1 == scriptEngineFromExec(exec)->scriptValueFromJSCValue(o2).toVariant();
+    return variant1 == QScriptEnginePrivate::toVariant(exec, o2);
 }
 
 QVariantPrototype::QVariantPrototype(JSC::ExecState* exec, WTF::PassRefPtr<JSC::Structure> structure,