[llvm] [KnownFPClass] Improve known class deductions for exp/exp2/exp10 (PR #217526)

[Eric Ross via llvm-commits]

ZERICO2005 wrote:

I updated the comments from `exp(x) is infinity if x > positive-subnormal` to `exp(x) is infinity if x > +1.0` and etc.

This also ties in nicely with potential future flags distinguishing between `x < 1.0`, `x == 1.0`, and `x > 1.0`.


https://github.com/llvm/llvm-project/pull/217526