It's really irritating that people take this condescending approach. C is harder to optimize than language that e.g. do not have pointers. That is a tradeoff the language designers chose because they wanted C programmers to be able to type pun, for example. This is why C89's only limit on type punning was memory alignment. The intent of "restrict" was to enable some aliasing optimizations via opt-in. So, sure, things that are not invariant in C are not available for invariant optimization. C permits aliasing. So it calls for smarter compiler techniques. If you want a language that forbids aliasing, use one that does and then call out to C libraries. But breaking C to allow CS220 "clever optimizing tricks" to be easily used is bad engineering. Essentially, what you are saying is, "elimination of invariants is a good optimization, so pretending C has more invariants than it does is a good thing. "

So maybe come up with a real example and stop hand waving.