[llvm] [LLVM] Slay undead copysign code (PR #111269)

[via llvm-commits]

workingjubilee wrote:

If a true database of all function calls that _might_ be made at runtime is desired, @arsenm, and not "all calls *that LLVM might generate*", then the .def file in question is hopelessly short. You have approximately the entirety of libc (minus _some_ of math.h), Win32, and POSIX APIs to include. I don't think setting _this_ list back by even a few more functions than this would be appreciable.

It doesn't even have:
- abs
- fdim
- nan
- remainder
- remquo
- hypot
- atan2
- acosh
- asinh
- atanh
- erf
- erfc
- lgamma
- tgamma
- modf (not to be confused with fmodf)
- scalbn
- log1p
- logb
- ilogb
- expm1
- nextafter
- nexttoward

...or all their differently-sized variants.

https://github.com/llvm/llvm-project/pull/111269