Remark val_lessdef_normalize:
  forall v v' ty,
  Val.has_type v ty -> Val.lessdef v v' ->
  Val.lessdef v (Val.load_result (chunk_of_type ty) v').

Lemma return_regs_arg_values: forall sg ls1 ls2, tailcall_is_possible sg = true -> map (fun p => Locmap.getpair p (return_regs ls1 ls2)) (loc_arguments sg) = map (fun p => Locmap.getpair p ls2) (loc_arguments sg).