App uploads to the iOS store in the LLVM's own Bitcode format is a distant echo of the CPU ISA agnostic IR approach IBM employed at the time. Bitcode is transpiled down to the underlying CPU instructions via the static binary translation and optimisation, and the translation between Bitcode -> x86 or Bitcode -> ARM has been possible to do for some time: https://www.highcaffeinecontent.com/blog/20190518-Translatin...

Rosetta 2 AOT, whilst not being exactly the same thing as the ISA agnostic IR solution, is another example of the static binary translation. Theoretically, Apple could start requiring OS X app submissions to the app store in the Bitcode format as well, so they could be transpiled and optimised at the app download time and perform efficiently on M3, M4, M5 etc CPU's in the future. However, with their habit of obsoleting certain things fast, it is not clear whether they will choose to go down the Bitcode path for the OS X apps.