let add_s sid acc =
let s, _ = Kernel_function.find_from_sid sid in
(* we add only 'simple' statements *)
match s.skind with
| Instr _ | Return _ | Continue _ | Break _ | Goto _
-> Cilutil.StmtSet.add s acc
| Block _ | Switch _ | If _ | UnspecifiedSequence _ | Loop _
| TryExcept _ | TryFinally _
-> acc