[llvm] [DAGCombiner] Fold (smax x (neg x)) to (abs x) (PR #164322)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

It looks like all the changed tests use non-canonical IR -- the middle-end already folds this. It would be good to demonstrate that this fold is useful in DAGCombine due to an interaction with legalization.

https://github.com/llvm/llvm-project/pull/164322