[llvm] [NFC][TTI] Introduce getInstructionUniformity API for uniformity analysis (PR #168903)

[Jay Foad via llvm-commits]

jayfoad wrote:

> ping jayfoad can you please review this NFC patch.

I'll get to it. I have hundreds of PRs in my inbox. FYI https://llvm.org/docs/CodeReview.html#code-reviews-speed-and-reciprocity says "the common courtesy ping rate is one week".

https://github.com/llvm/llvm-project/pull/168903