[CUDA] math functions support list

[jinz2014]

I think a table of math functions is needed for people to know which math functions are supported...

https://github.com/codeplaysoftware/computecpp-sdk/blob/master/samples/monte-carlo-pi.cpp
~/computecpp-sdk/samples$ clang++ -fsycl -fsycl-targets=nvptx64-nvidia-cuda-sycldevice monte-carlo-pi.cpp
ptxas fatal : Unresolved extern function '_Z18__spirv_ocl_lengthDv2_f'

Add another one
ptxas fatal : Unresolved extern function '_Z15__spirv_ocl_tanf'

[alexbatashev]

@Ruyk are all builtins listed on https://github.com/intel/llvm/blob/sycl/sycl/doc/cuda/cuda-vs-opencl-math-builtin-precisions.md supported by the backend?

[Ruyk]

Not yet, we are working on the full list, @Naghasan has the details

[Ruyk]

The complete working set of builtins required for SYCL 1.2.1 will be available in the next few weeks. Patches are being reviewed, check the libclc label (https://github.com/intel/llvm/pulls?q=is%3Apr+label%3Alibclc+)

[bader]

@jinz2014, most of the built-ins are implemented. Can we close this issue?

[jinz2014]

Though I am not a developer, I am interested to know where I can find the implementations. Thank you for pointing that out.

[bader]

These functions are implemented in libclc library.
Particularly _Z15__spirv_ocl_tanf definition should be added by #1990 and _Z18__spirv_ocl_lengthDv2_f by #1832.

You can find related PRs using the link provided by @Ruyk above.