It also raise another question: does these primitives support mirror approach? (when it can be called with receiver as first argument?)

Yes I made sure the mirror approach works. Even better, there are tests ensuring that it works. You can see in the class WriteBarrierTest that objects can become read-only through an instance of TTMirror, look for example into the users of TTMirror>>#setIsReadOnlyObjectOf: object to: boolean.