Proof with eauto 15 with reg_renamings val_renamings.
intros.
assert (Hinjective := injective (weak_obs_eq Hmem_obs_eq)).
unfold compare_longs...
Qed.

(* Specifications: *)
Lemma compare_floats32_ren:
forall f rs rs' v1 v2 v1' v2'
(Hval_obs: val_obs f v1 v1')
(Hval_obs': val_obs f v2 v2')
(Hrs_ren: regset_ren f rs rs'),
regset_ren f (compare_floats32 v1 v2 rs)
(compare_floats32 v1' v2' rs').