Hint Rewrite @subst_stackframe_of : subst.

Lemma subst_remove_localdef_PQR: forall P Q R i v,
subst i v (PROPx P (LOCALx (remove_localdef_temp i Q) (SEPx R))) |-- PROPx P (LOCALx (remove_localdef_temp i Q) (SEPx R)).