Open Scope logic.
Instance CompSpecs : compspecs. make_compspecs prog. Defined.
Definition Vprog : varspecs. mk_varspecs prog. Defined.
Definition t_struct_elem := Tstruct _elem noattr.
Definition t_struct_fifo := Tstruct _fifo noattr.
Instance QS: listspec _elem _next (fun _ _ => emp).

Lemma Qsh_Qsh': sepalg.join Qsh Qsh' Ews.