[llvm] [AMDGPU] Eliminate likely-spurious execz checks (PR #117567)

[Jay Foad via llvm-commits]

jayfoad wrote:

I still don't really understand...

Are you trying to identify branches whose condition is divergent according to UA, but is likely to be uniform in practice?

How can branch weights tell you whether the branch is likely uniform or not? I guess if it's likely uniform-and-true or uniform-and-false then they can tell you that.

For what kind of branches do you want to influence the exec-skipping logic? Can you give an example?

https://github.com/llvm/llvm-project/pull/117567