Definition size_compatible' (n: Z) (p: val) :=
match p with
| Vundef => True
| Vint _ => True
| Vlong _ => True
| Vfloat _ => True
| Vsingle _ => True
| Vptr _ i_ofs => Ptrofs.unsigned i_ofs + n < Ptrofs.modulus
end.

Lemma access_mode_by_value: forall t, type_is_by_value t = true -> exists ch, access_mode t = By_value ch.