[llvm] [TTI] Introduce getInstructionUniformity API for flexible uniformity analysis (PR #137639)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

What happened to the idea of a preliminary NFC patch to introduce TTI::getInstructionUniformity as a replacement for isAlwaysUniform/isSourceOfDivergence?

https://github.com/llvm/llvm-project/pull/137639