[fishywang]

https://en.wikipedia.org/wiki/X86-64#Microarchitecture_level...

amd64 v3 are instructions included in CPUs starting from 2013, so basically any modern amd64 cpu supports all of them. As mentioned there on the Wikipedia page, QEMU 7.2 also implemented all of them. Those are more efficient instructions, thus "free performance boost".

But Rosetta doesn't. Which instruction(s) it doesn't implement doesn't really matter (I can't remember either). What matters is that when it runs an instruction it doesn't implement, it will throw an illegal instruction error and the code hard crashes.

So because of Rosetta, we can't build code with amd64 v3 enabled, and cannot have free performance boost (nice things).

[mrpippy]

Rosetta now supports AVX and AVX2 on Sequoia, but I believe all the others are missing (F16C, BMI, OSXSAVE definitely are not there)