[llvm] [AArch64] Enable CmpBcc fusion for Neoverse-v2 (PR #90608)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

> When I compile the llvm-test-suite + 3 versions of spec, notably the _instruction_ count overall increases by 0.1%.

Everything you wrote is spot and are things we have seen too, e.g. the instruction count and a bit of noise, register pressure. We have one very good motivating example (Eigen), but the rest is neutral. We need to double check that this Eigen improvement is real because there are some minor code changes elsewhere too. E.g., we have also seen some extra MOVs being introduced (probably the extra instruction count), and eliminating that might be a good way to improve things, but I will let Elvina confirm and comment on that.

https://github.com/llvm/llvm-project/pull/90608