Proof with eauto 10 with wd.
intros.
unfold compare_floats.
destruct v1; try (apply regset_wd_undef; eauto with wd).
destruct v2;
try (apply regset_wd_undef; eauto with wd).
eauto 8 with wd.
Qed.
Hint Resolve valid_val_compare_floats : wd.

Lemma regset_wd_compare_floats:
forall f rs v1 v2,
regset_wd f rs ->
regset_wd f (compare_floats v1 v2 rs).