[llvm] SelectionDAG/expandFMINIMUMNUM_FMAXIMUMNUM: FCANONICALIZE is needed only for sNaN (PR #108180)

Matt Arsenault via llvm-commits llvm-commits at lists.llvm.org
Sun Sep 15 06:11:07 PDT 2024


arsenm wrote:

> I guess t hat I am confused by `nofpclass` in https://llvm.org/docs/LangRef.html#id1932. Can it used to mark an argument that it will never be a type?
> 
> I have a try, while it won't as `DAG.isKnownNeverNaN` won't return true in this case. Maybe I misunderstand its meaning.

isKnownNeverNaN is quite underdeveloped. You can most easily test the no-nan operand case by just having a filler fadd nnan instruction. It would be simpler to do that than pulling in a dependency on some more general nofpclass handling 

https://github.com/llvm/llvm-project/pull/108180


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