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

[Pankaj Dwivedi via llvm-commits]

PankajDwivedi-25 wrote:

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

As per our previous discussion, it's better to make that part of this patch only to catch any edge case?

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