Lower coordination cost is a big deal. Having your own backend means you can do frontend-backend codesign. You can implement language specific optimizations in

Lower coordination cost is a big deal. Having your own backend means you can do frontend-backend codesign. You can implement language specific optimizations in the backend. Those things are not in the cards if you’re using llvm. (I mean they might be, but unless you fork, the time it’ll take for the changes to make it into llvm will be comparable to the time it takes to write your own backend.)