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 in_prog_vars_in_prog_defs: forall i v prog, In (i,v) (prog_vars prog) -> In (i, Gvar v) (prog_defs prog).