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

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choikwa wrote:

Updated and addressed feedback except the triplet check. At the moment, I'm unsure if there is better way than to query using llvm::isLibFuncEmittable, but that requires TLI.

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