message: Executable "jump to entry" test
diff: -@gcd(a: int): int {
  +@main(a: int) {
  .while.cond:
  zero: int = const 0;
  is_term: bool = eq a zero;
  a: int = sub a one;
  jmp .while.cond;
  .while.finish:
  - ret a;
  + print a;
  }
  