[llvm] [SimplifyLibCalls] Constant fold scalbxx (PR #114417)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

This is handled in the wrong place, and is much more complicated than necessary.

The natural place for this is in lib/Analysis/ConstantFolding.cpp. You also do not need to match all the special cases, you can just use APFloat::scalbn.

scalbn is really just an alias for ldexp anyway, so really we should just canonicalize these into the ldexp intrinsic 



https://github.com/llvm/llvm-project/pull/114417