I don&#x27;t see why a new compiler would be necessary. It&#x27;s unlikely they&#x27;d completely throw out the whole ARM ISA and replace it with something completely different in one go. More likely, they&#x27;ll gradually add new instructions and mutate the characteristics of existing instructions over time. LLVM IR isn&#x27;t completely ISA agnostic, a lot of ISA specific assumptions are still baked into it, but gradual iterative improvement is Apple&#x27;s speciality. A couple of new instructions this year, deprecate a few old one next, and in 5 years time you&#x27;ve got a new ISA that&#x27;s barely recognizably ARM any more yet each step along the way is just an incremental and largely backwards compatible change.