Definition main_params (ge: genv) start : Prop :=
  exists b, exists func,
    Genv.find_symbol ge start = Some b /\
        Genv.find_funct ge (Vptr b Ptrofs.zero) = Some (Internal func) /\
        func.(fn_params) = nil.

Lemma find_funct_ptr_exists: forall (p: program) id f, list_norepet (prog_defs_names p) -> In (id, Gfun f) (prog_defs p) -> exists b, Genv.find_symbol (Genv.globalenv p) id = Some b /\ Genv.find_funct_ptr (Genv.globalenv p) b = Some f.