It is a common theme in computer architecture for someone to say, &#x27;look I have an awesome new architecture all you need is a clever compiler to make it work&#x27;.  None of them really pan out (other than in specific applications, you could argue GPGPU is as an example, though that appeared more by accident than by design).<p>Apple would need a very good reason to produce their own ISA.  Sure they like to do many things in house but they don&#x27;t do everything themselves.  The resources required to produce and support a whole new ISA are a major investment, they&#x27;re only going to do it if in the long run is cheaper than paying for an ARM architecture license.  I just don&#x27;t see a solid argument that a custom ISA and shiny new compiler would give them much (if indeed anything).<p>Whilst they may be shipping LLVM IR for the watch apps rather than ARM code I think this is just so they can target the compile for a specific processor.  Each one has its own performance quirks and especially in such a power sensitive environment it would make sense to do specific targetting.