A “sufficiently smart compiler” is a (frequently mythical) one that can implement some difficult optimization on its own, rather than needing hints from the programmer. (See e.g. https://prog21.dadgum.com/40.html?0 for some discussion on the topic.)
Ah interesting. I wonder if LLMs can help solve that, although if they don't know the programmer's intent, they likely won't be able to optimize any better either.
