let var_name = function
| VarT (v, None, _,_) -> v
| VarT (v, Some id, _,_) -> Printf.sprintf "%s_%d" v id
| VarL (v, _) ->
let name = v.Cil_types.lv_name in
match v.Cil_types.lv_origin with
| Some _ -> name
| _ -> Printf.sprintf "%s__%d" name v.Cil_types.lv_id