[llvm] [UniformityAnalysis] Skip CycleAnalysis on targets without branch divergence (PR #189948)

[Jay Foad via llvm-commits]

jayfoad wrote:

> > I'm slightly surprised that this does not affect tests like `test/CodeGen/AMDGPU/llc-pipeline-npm.ll`.
> 
> isn't this beacuse test runs with `-mtriple=amdgcn--amdhsa`, so hasBranchDivergence() returns true?

Yes you're right. I was thinking about similar tests for other targets. I thought they might show that cycle analysis is no longer run in some cases.

https://github.com/llvm/llvm-project/pull/189948