[llvm] [SelectionDAG] Improve ucmp/scmp codegen (PR #190787)

[Craig Topper via llvm-commits]

topperc wrote:

This commit structure in this isn't very reviewable now. The commit that added the ucmp fold also adds the new tests. This makes it impossible to see the current codegen for these tests and how this patch changes it. I'd recommend starting a new PR with a clean set of commits. Adding new tests in the first commit and the code changes in the second commit.

https://github.com/llvm/llvm-project/pull/190787