For OpenMP target regions to piggy back on the CUDA/AMDGPU/... implementation of math functions,
we include the appropriate definitions inside of an `omp begin/end declare variant match(device={arch(nvptx)})` scope.
This way, the vendor specific math functions will become specialized versions of the system math functions.
When a system math function is called and specialized version is available the selection logic introduced in D75779
instead call the specialized version. In contrast to the code path we used so far, the system header is actually included.
This means functions without specialized versions are available and so are macro definitions.
This should address PR42061, PR42798, and PR42799.
Reviewed By: ye-luo
Differential Revision: https://reviews.llvm.org/D75788
In d1705c1196 (D77238) we accidentally included subsequent changes and
did not only move the code into a new file (which was the intention).
We undo the changes now and re-introduce them with the appropriate test
changes later.
This is not supported to change anything but allow us to reuse the math
functions separately from the device functions, e.g., source them at
different times. This will be used by the OpenMP overlay.
This also adds two `return` keywords that were missing.
Reviewed By: tra
Differential Revision: https://reviews.llvm.org/D77238
Johannes Doerfert