Everyone here seems to be making this solely about the processor, which it is partially, but the other story is that Rosetta 2 is looking really good. Obviously there’s plenty more to test beyond a GeekBench benchmark, but hitting nearly 80% of native performance shows both the benefits of ahead-of-time transpiling and the sophistication of Apple's implementation.

I’ll still be waiting to see what latency-sensitive performance is like (specifically audio plugins) but this is halfway to addressing my biggest concern about buying an M-series Mac while the software market is still finding its footing.

I am similarly curious about Rosetta2, but there seems to be very little marketing let alone technical information being made available. All I can figure is that it performs user mode emulation, similar to what QEmu can do, and does not cover some of the newer instructions.

Off topic, my job has been in virtualisation for the last 12 years, thus I am very familiar with the publicly available body of research on this topic. Ahead of time binary translation has been a niche area at best.

Rosetta 2 is an AOT translation, not emulation.

https://developer.apple.com/documentation/apple_silicon/abou...

Understood, I called this "ahead of time binary translation" in my post above, and I know it would use JIT-based emulation when necessary.

It seems to me that the correct term is "Static Binary Translation" (SBT) for what you call "ahead of time binary translation".

And the correct term for "JIT-based emulation" is "Dynamic Binary Translation" (DBT).

At least these are the terms you should use if you want to find some literature on this subject.

We're not talking about JIT or AOT compiler because it's not really a compilation (compilation is translating to a lower level language).

I think a lot of people talk about JIT rather than DBT because the JIT term is better known, and there is confusion when Apple says they do "Dynamic translation for JITs". Which means that: they do DBT to handle applications that use JIT.

Edit: So Rossetta 2 does both: SBT and DBT.

You are correct, static binary translation is what Rosetta does first. That, however, is what I called niche technology in another post, most of the research so far had focused on dynamic binary translation.

Furthermore, SBT, even for user mode binaries, can rarely reach the performance levels that we see with Rosetta2. There are many issues in determining what is code, where are the branch destinations in case of indirect branches, etc. What we have here is certainly a feat of engineering on its own.

> There are many issues in determining what is code, where are the branch destinations in case of indirect branches, etc.

Yes, handling indrect branch seems a bit complex and I'm not a specialist in the field. But I'm pretty sure that the cases of indirect branch are rare enough so that an additional indirection is relatively inexpensive. Adding a simple address mapping table should meet most of the cases.

An interesting question would also be whether Apple has added features to the hardware to improve the translation?

We know, for example, that Apple introduced a special register [1] to temporarily switch from the ARM consistency model to the TSO consistency model (Total Store Order) from x86.

[1] : https://github.com/saagarjha/TSOEnabler