Remark int64_shru'_div_two_p:
  forall x y, Int64.shru' x y = Int64.repr (Int64.unsigned x / two_p (Int.unsigned y)).

Lemma eval_mod_from_div: forall le a n x y, eval_expr ge sp e m le a (Vint y) -> nth_error le O = Some (Vint x) -> eval_expr ge sp e m le (mod_from_div a n) (Vint (Int.sub x (Int.mul y n))).