> I'm not aware of any general-purpose language where this is an option to any significant degree (silent AOS-to-SOA, hot-vs-cold data segregation, tree clustering, etc...)

Not yet, of course, because it hasn't been released, but Jonathan Blow's Jai language offers transparent switching between AOS and SOA, as well as many other features that make it easy to explore the 'optimization space' of a program manually.

https://www.youtube.com/watch?v=ZHqFrNyLlpA

(for those who don't know, Jonathan Blow was the creator of Braid)