[llvm] LangRef: Clarify llvm.minnum and llvm.maxnum about sNaN and signed zero (PR #112852)

[YunQiang Su via llvm-commits]

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@@ -16574,21 +16574,34 @@ type.
 
 Semantics:
 """"""""""
+Follows the semantics of mininumNumber in IEEE-754-2019, except for signaling NaNs. If either operand
+is an sNaN, the result is always a qNaN. This matches the recommended behavior for the libm
+function `fmin`, although not all implementations have implemented these recommended behaviors.
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wzssyqa wrote:

Yes. We describe it with both 2008/2019. Wish it may be clearer..

https://github.com/llvm/llvm-project/pull/112852