AVX512-IFMA & AVX10 status

[pinkforest]

Re: https://rustcrypto.zulipchat.com/#narrow/stream/260040-elliptic-curves/topic/AVX-512.20IFMA.20.2F.20AVX10.20future

This is probably still 1) worth supporting and this may be still 2) set as default without heavy opt-in ?

The downside by keeping it as default nightly-on is dealing with the nightly stuff changes if any

The upside is that the current AMD consumer flagships seems to be have good numbers and performance-per-watt with it that would indicate the enterprise stuff may work well as well.

I don't have 7950X to test withbut phoronix has some general numbers: https://www.phoronix.com/review/amd-zen4-avx512

intel however seems to have pretty much yanked it by now and AVX10 seems to promise a lot and legacy backwards compatibility. chipsandcheese thinks AVX10 is a silly idea and the register has interesting article + tom's hardware hot take.

This also poses a question how AVX-512 code is tested reasonably and does it need to be changed in near future - it doesn't currently really change at all but anyways 🤷‍♀️

Thoughts ?