Myth: Your compiler is always smarter than you
Truth: No it's not for some "you", and you CAN acquire the knowledge to (frequently) beat it in your domain.
A 2h demonstration by @cmuratori
https://www.youtube.com/watch?v=R5tBY9Zyw6o …
I'd love a commentary by @rygorous on the inidividual findings.
It is not a front-end issue, apparently, because it does pass a memcpy down to the actual codegen. Someone posted a llvm-dev question here (http://lists.llvm.org/pipermail/llvm-dev/2020-September/145367.html …), but nobody responded.