[llvm] [SelectionDAG] Avoid one comparison when legalizing fmaximum (PR #142732)

[Benjamin Kramer via llvm-commits]

d0k wrote:

> We already know at this point that both values must be +/-0.0

Isn't it just one of them that must be +/-0.0? We only know that the other value is smaller (max)/bigger (min) than 0.

> only check the sign of one of the values

If we were actually checking the sign this would work, but we compare equality with integer 0.

https://github.com/llvm/llvm-project/pull/142732