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.