[llvm] ConstantFold logl calls (PR #94944)

[David Green via llvm-commits]

https://github.com/davemgreen approved this pull request.

> Makes sense, I've removed the checks for log.f128 then. With logl infinity, I was unsure whether the fact it hasn't retained the original logl call was correct behaviour or not.

It looks like it doesn't generate a pole error for infinity when I tried it (only for zero), so I think that sounds OK. From what I can tell this LGTM, thanks.

https://github.com/llvm/llvm-project/pull/94944