[clang] [AMDGPU][clang] provide device implementation for __builtin_logb and … (PR #129347)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> I would have preferred to do the overloads in the target specific header file, but __builtin_* methods couldn't be overloaded. I noticed that hip math header already overloads 'double logb(double)' by calling ocml version, so I mirrored that in clang. If there is better approach, I am interested.

Long term, I think it's as I outlined in my RFC that I linked earlier.

https://github.com/llvm/llvm-project/pull/129347