[llvm] [InstCombine] Handle isNanOrInf idioms (PR #80414)

[Andy Kaylor via llvm-commits]

andykaylor wrote:

@dtcxzyw FYI, this patch and your similar recent changes introduce runtime library calls with fp128 (https://godbolt.org/z/PWcjK86vz) so it's a bit of a de-optimization in that case. I think @FreddyLeaf will look into this when he returns from holiday. We should be able to fix this in the selection DAG.

@pranavk has been working on fp128-related issues, so may also want to be aware of this.

https://github.com/llvm/llvm-project/pull/80414