[clang] [llvm] [AArch64] FEAT_SPEv1p2 is optional in v8.7-A and v9.2-A (PR #123336)

[David Green via llvm-commits]

davemgreen wrote:

I agree the current behaviour isn't very consistent. It would be good to come up with a single rule and stick to it, whatever it is. FeatureAMVS / FEAT_AMUv1p1 came up recently too, which is enabled for some cpus that do not have it (like Neoverse V3).

It looks like GCC is the "precise" option for the -mcpu and enabled for 8.7+, which sounds OK to me if this now mirrors.

https://github.com/llvm/llvm-project/pull/123336