Remark agree_regs_init:
forall F ctx rs, agree_regs F ctx (Regmap.init Vundef) rs.

Lemma agree_regs_init_regs:
forall F ctx rl vl vl',
Val.inject_list F vl vl' ->
(forall r, In r rl -> Ple r ctx.(mreg)) ->
agree_regs F ctx (init_regs vl rl) (init_regs vl' (sregs ctx rl)).