Definition StoreEffect (tv:val)(vl : list memval) (b:Values.block) (z:Z):bool :=
  match tv with Vptr bb ofs => eq_block bb b &&
             zle (Ptrofs.unsigned ofs) z && zlt z (Ptrofs.unsigned ofs + Z.of_nat (length vl))
         | _ => false
  end.

Lemma storev_curWR ch m vaddr v m' (ST:Mem.storev ch m vaddr v = Some m') b z (EFF : StoreEffect vaddr (encode_val ch v) b z = true): Mem.perm m b z Cur Writable.