`Dict.insert` stuck in infinite loop: optimized build

[bhansconnect]

No idea what is going on, but in a lisp interpreter posted on zulip, roc looks to be getting stuck in an infinite loop if run with optimized builds. Probably something wrong with llvm allocas and joinpoints? That at least seems like a reasonable guess. That or maybe llvm misunstanding an alloca lifetime cause we don't label it correctly (not sure how that works with loops).

Repro source (not minimized):
https://github.com/raymyers/roc-lisp/blob/1ddb69def35a31cbf00d0f8dcd5b1815a5cd20b8/main.roc

Just build and feed in this example:

(define fib (lambda (n) (if (<= n 2) 1 (+ (fib (- n 1)) (fib (- n 2))))))
(fib 18)