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_modl_from_divl: forall le a n x y, eval_expr ge sp e m le a (Vlong y) -> nth_error le O = Some (Vlong x) -> eval_expr ge sp e m le (modl_from_divl a n) (Vlong (Int64.sub x (Int64.mul y n))).