I haven't kept up with POWER after POWER9, but I recall it to be a true hardwired control RISC, pure as the driven snow. This had some interesting properties (

I haven't kept up with POWER after POWER9, but I recall it to be a true hardwired control RISC, pure as the driven snow. This had some interesting properties (along with other clever designs like eFuses and pNOR) for creating a really credible security posture. They do have a millicode system and chicken bits for oops moments (which are kind of an opposite risk, if you don't get those right for unexpected problems).