let result_var kf =
let kf_id = Kernel_function.get_id kf in
try Hashtbl.find kf_var_res kf_id
with Not_found ->
let name = (Kernel_function.get_name kf)^"_FRAMA_C_RESULT" in
let ret_type = Kernel_function.get_return_type kf in
let v = Cil_const.make_logic_var name (Ctype ret_type) in
Hashtbl.add kf_var_res kf_id v;
v