Firstly, "ignoring the situation completely with unpredictable results" is a pretty clear permission to do arbitrary optimizations, as long as they preserve the

Firstly, "ignoring the situation completely with unpredictable results" is a pretty clear permission to do arbitrary optimizations, as long as they preserve the semantics in the case where the execution doesn't exhibit UB. Secondly, in ISO standards Notes are by definition non-normative, hence your exegesis as it pertains to C99 and later versions is invalid anyway.