[llvm] [InstCombine] Don't convert a compare+select into a minnum/maxnum intrinsic that can't be lowered back to a compare+select (PR #177821)

[Florian Hahn via llvm-commits]

fhahn wrote:

Yes, with fast-math we can unroll this and introduce parallel reductions. See the code added in https://github.com/llvm/llvm-project/pull/149470  & https://github.com/llvm/llvm-project/pull/166630. Extending for min/max reductions should be fairly straigth-forward 

https://github.com/llvm/llvm-project/pull/177821