Definition compat_pointer_chunks (chunk1 chunk2: memory_chunk) : Prop :=
match chunk1, chunk2 with
| (Mint32 | Many32), (Mint32 | Many32) => True
| (Mint64 | Many64), (Mint64 | Many64) => True
| _, _ => False
end.

Theorem load_store_pointer_mismatch:
forall chunk m1 b ofs v_b v_o m2 chunk' v,
store chunk m1 b ofs (Vptr v_b v_o) = Some m2 ->
load chunk' m2 b ofs = Some v ->
~compat_pointer_chunks chunk chunk' ->
v = Vundef.