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_overlap: forall chunk m1 b ofs v_b v_o m2 chunk' ofs' v, store chunk m1 b ofs (Vptr v_b v_o) = Some m2 -> load chunk' m2 b ofs' = Some v -> ofs' <> ofs -> ofs' + size_chunk chunk' > ofs -> ofs + size_chunk chunk > ofs' -> v = Vundef.