Definition memory_block (sh: share) (n: Z) (v: val) : mpred :=
match v with
| Vptr b ofs => (!!(Ptrofs.unsigned ofs + n < Ptrofs.modulus)) && memory_block' sh (nat_of_Z n) b (Ptrofs.unsigned ofs)
| _ => FF
end.

Lemma mapsto_pointer_void:
forall sh t a,
eqb_type (Tpointer t a) int_or_ptr_type = false ->
eqb_type (Tpointer Tvoid a) int_or_ptr_type = false ->
mapsto sh (Tpointer t a) = mapsto sh (Tpointer Tvoid a).