Proof with eauto with reg_renamings val_renamings.
intros.
inversion Harg; subst.
eapply extcall_arg_reg in H; eauto.
destruct H as [arg' [Harg' Hobs_arg]].
exists arg'.
split...
constructor; auto.
eapply extcall_arg_reg in H; eauto.
eapply extcall_arg_reg in H0; eauto.
destruct H as [vhi' [Hhi' Hobs_hi]].
destruct H0 as [vlo' [Hlo' Hobs_lo]].
exists (Val.longofwords vhi' vlo').
split...
constructor; auto.
Qed.

Lemma core_inj_wd:
forall f c c',
core_inj f c c' ->
core_wd f c.