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 memory_block_conflict: forall sh n m p,
nonunit sh ->
0 < n <= Ptrofs.max_unsigned -> 0 < m <= Ptrofs.max_unsigned ->
memory_block sh n p * memory_block sh m p |-- FF.