There are plenty of cases where flattening an object that takes 64bits would make sense.

The current code will help with `Integer[]`, `Char []`, etc, as well as combinations of `byte`, `char`, and `int`. Past that it doesn't really help much.

It would be fantastic if we could also flatten something like `Pair` or `Tuple`. However, even with compressed pointers, that is 64 bits, so that, plus the `null` bit, means it can't be flattened, which is a real shame. For various reasons, I have `List<Long>` in numerous places in my code, It would be great if that could also be flattened. However, since a Long is 64 bits, it _also_ can't be flattened. https://openjdk.org/jeps/8316779 would go a long way to to helping here, since then at least the null bit could be thrown away, which would allow more things to be flattened.

And then, if you want to go Wishlist land, something that would allow SSO (Small String Optimisation) would also be awesome, but that would require something akin to unions in Java, which we can _kind_ of do with sealed classes, but, since String is a final class, can't be retrofitted back into the language.

Does anyone know if Valhalla will flatten "simple" sealed classes, where every sealed class is small enough to be flattened? Since that would also be a powerful example to share.