let subst_havoc env a =
let xzone = xzone_assigned a in
let m_here = mem_at env Clabels.Here in
let vmh = vbits_of_mem m_here in
(* let v = D.fresh "v" (Mdata.Vmodel(Formula.ADT("bits",[]))) in
let bits = tbits_of_var v in *)
let new_vmh sigma =
let mb = D.apply sigma (F.var vmh) in
F.wrap (RtLib.havoc mb (Tint.term_of_xzone xzone))
(* missing hyp about [bits] size :
* F.wrap (RtLib.store mb (Tint.term_of_xzone xzone) bits) *)
in
[(* D.Fresh v; *) D.Update(vmh, new_vmh)]