Hello,
I have already benchmarked this when Arch was considering a similar move:
https://openbenchmarking.org/result/2103142-HA-UARCHLEVE55
There is no or negligible performance benefit of compiling for x86_64-v2 versus
amd64 baseline. For discussion see [1]. Beforehand, I have explicitly selected
benchmarks that gave the largest performance difference when run with -O1 and
-O3 compiler flags and were expected to show the biggest benefit from uarch
optimizations.
I think that there is really no point in requiring x86_64-v2 as the compilers
simply do not take much advantage from it.
Some cursory examination of the new x86_64 sublevels seem to indicate
that
x86_64-v2 goes back to roughly 2007~2008, merely cutting off the first couple
of generations of x86_64 CPUs from Intel and AMD.
AMD introduced SSE4.2 much later
then Intel - starting with Jaguar in 2013-2014.
Greetings,
Mateusz
[1]
https://lists.archlinux.org/pipermail/arch-general/2021-March/048739.html