Ltac destruct_cjoin phi HH :=
  match goal with
   |   |- context [@proj1_sig rmap _ ?X] => destruct X as [phi HH]; simpl
   |  H: context [@proj1_sig rmap _ ?X] |- _ => destruct X as [phi HH]; simpl in H
  end.

Lemma dec_pure: forall r, {exists k, exists pp, r = PURE k pp}+{core r = NO Share.bot bot_unreadable}.