x/sys/cpu: No flag for SVE2 detection

[mhr3]

Go version

go version go1.22.1 darwin/arm64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='arm64'

What did you do?

When using the ARM64 struct from x/sys/cpu, there's no field for SVE2 support.

What did you see happen?

No HasSVE2 field.

What did you expect to see?

New arm64 chips from AWS/Azure/Google/Nvidia/Alibaba have support for SVE2, by adding this flag, go programs can implement SVE2 optimized code.

[gopherbot]

Change https://go.dev/cl/580655 mentions this issue: cpu: add support for sve2 detection