let rec sizeof = function
    | C_comp cinfo ->
        List.fold_left
          (fun sz f -> F.i_add sz
             (sizeof (object_of f.ftype))) F.i_zero cinfo.cfields
    | C_array ainfo ->
        begin
          match ainfo.arr_flat with
            | Some a -> F.i_mult
                (sizeof (object_of a.arr_cell))
                  (F.e_int64 a.arr_cell_nbr)
            | None -> WpLog.not_yet_implemented "[Store] Sizeof unknown-size array"
        end
    | _ -> F.i_one