Add and substract were the main culprits here.
We are trying to more towards a state where:
* Every IR op can expect it isn't given extra bits
on it's input
* Every IR op never sets more bits than it's size
* All unnessicary BFEs are never emitted
* ARM doesn't have to implement special 8 and 16bit versions of IR ops
All masking required to implement 8/16bit math on
arm should be explictly generated from Opcode decoder