Ok taking a step back I just realized you aren't 'remram :P But anyways my point was that in the old scheme if you wanted to know where the class was you would do some arithmetic on the compressed pointer to get a full pointer and now you can do a comparison, or if you want to read something do a dereference. Assuming the new layout is an array of classes you have a similar scheme where you have an index and you can compare those directly, and if you want data in the class you deref.
Also, i believe that 'classes' aren't fixed size, because they contain the class's vtable [1]. As such, you couldn't keep them in an indexable array anyway.
> in the old scheme if you wanted to know where the class was you would do some arithmetic on the compressed pointer to get a full pointer and now you can do a comparison
Well also you didn't actually need to decompress the pointer first - compressed pointers are unique as well of course.
