Re: The royal WEEE ???
It depends what you mean by globally visible state.
All these performance enhancements preserve globally visible state in the sense that the state that is intended to be visible (registers, flags, memory contents) are indeed preserved as they should. The things that are not preserved are things that are not actually defined - such as the execution times of certain operations.
This is a Rumsfeld problem: since CPU architectures are defined in specifically defined in terms of what is visible and known, anything else that is observable - and that potentially conveys information - is an unknown unknown...