Is it a good idea to downcast Hash

[Hlaaftana]

It wouldn't necessarily help, but if aligning the uint32 does any extra work 
that extra work would be gone. If you are not doing any calculations on `LitId` 
either, then you won't be doing anything that would be faster if it had less 
bits. In this case though the normal performance pitfalls that come with 
alignment don't really apply.