let field loc f =
if f.fcomp.cstruct then
let pos = offset_of_field f in
let cv = Ctypes.object_of f.ftype in
match loc with
| Loc l ->
Loc (upd_obj (upd_off l (F.i_add l.off pos)) cv)
| Addr (p,_) -> Addr (model_addr_shift p pos,cv)
else
unsupported "union field"