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.