If either the standard library or a user function define other operations beside arithmetic ones on it, they are available. Why should they be UB, if implemented correctly? If the implementation in the standard library or the user function uses a SIMD or SHA unit, those operations are accelerated by that hardware unit. If data has to be moved from memory or general purpose registers to special registers of this hardware unit, it is moved by the implementation. If special alignment requirements have to be adhered to, the implementation will solve those.   So of course it will unlock everything, which somebody (standard or user library) implemented using those types.   Apart from that, even arithmetic operations on unusual bit sizes are a neat feature.   -----Ursprüngliche Nachricht----- Von:Tiago Freire <tmiguelf_at_[hidden]> Gesendet:Fr 05.09.2025 23:15 Betreff:RE: [std-proposals] D3666R0 Bit-precise integers An:std-proposals_at_[hidden]; CC:Sebastian Wittmeier <wittmeier_at_[hidden]>; Well, if all you want to do is integer arithmetic, it will allow you to do just that. Everything else is UB. It won’t unlock access to SIMD or similar.