Remark eval_builtin_args_trivial:
forall (ge: RTL.genv) (rs: regset) sp m rl,
eval_builtin_args ge (fun r => rs#r) sp m (List.map (@BA reg) rl) rs##rl.

Lemma transl_condexpr_CElet_correct:
forall le a b v1 v2,
eval_expr ge sp e m le a v1 ->
transl_expr_prop le a v1 ->
eval_condexpr ge sp e m (v1 :: le) b v2 ->
transl_condexpr_prop (v1 :: le) b v2 ->
transl_condexpr_prop le (CElet a b) v2.