Local Open Scope logic.
Definition load8 id ofs :=
(Sset id
(Ederef
(Ebinop Oadd
(Efield
(Ederef (Etempvar _ctx (tptr t_struct_SHA256state_st))
t_struct_SHA256state_st) _h (tarray tuint 8))
(Econst_int (Int.repr ofs) tint) (tptr tuint)) tuint)).

Lemma Znth_is_int:
forall i r,
0 <=  i < Zlength r ->
is_int I32 Unsigned (Znth i (map Vint r)).