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

[Pankaj Dwivedi via llvm-commits]

PankajDwivedi-25 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?

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