Remark val_lessdef_normalize:
forall v v' ty,
Val.has_type v ty -> Val.lessdef v v' ->
Val.lessdef v (Val.load_result (chunk_of_type ty) v').

Lemma in_subst_loc_pair:
forall l1 l2 l2' q (e e': eqs),
EqSet.In q e ->
subst_loc_pair l1 l2  l2' e = Some e' ->
(eloc q = l1 /\ ekind q = Full /\ EqSet.In (Eq High (ereg q) l2) e' /\ EqSet.In (Eq Low (ereg q) l2') e')
\/ (Loc.diff l1 (eloc q) /\ EqSet.In q e').