Include DPCT headers from system installation and remove the local copy

[rafbiels]

• Remove the outdated copy of DPCT headers in src_sycl/include
• Add cmake find module for DPCT
• Use the DPCT headers in src_sycl/CMakeLists.txt from the cmake module

The DPCT is part of the oneAPI base toolkit so if dpcpp/icpx is available, it is almost certain dpct is also installed. The find module looks in the most common oneAPI installation paths and standard system header locations. It works out of the box in the oneAPI environment (after sourcing the setvars.sh script). It is also possible to specify the location during cmake configuration using -Ddpct_LOCATION=/my/custom/location.

[rodburns]

@joeatodd Can you please confirm you are happy with the approach?

[irudkin]

Why did the project use its own local copy of some of the SDK files?

[irudkin]

Taking the zip of this version of the project and coping it over to Slurm to build in parallel with the 'main' version, I got the following error when building the nbody_dpcpp.sh: (using module cuda/11.7.1)

[ 93%] Building CXX object src_sycl/CMakeFiles/nbody_dpcpp.dir/shader.cpp.o
clang++: warning: CUDA version is newer than the latest supported version 11.5 [-Wunknown-cuda-version]
[100%] Linking CXX executable /home/illya/Dev/CodeplayExamples/cuda-to-sycl-nbody-dpct-includes/nbody_dpcpp
clang++: warning: linked binaries do not contain expected 'nvptx64-nvidia-cuda' target; found targets: 'spir64-unknown-unknown, nvptx64-nvidia-cuda-sm_86' [-Wsycl-target]
clang++: warning: CUDA version is newer than the latest supported version 11.5 [-Wunknown-cuda-version]
error: linking module flags 'nvvm-reflect-ftz': IDs have conflicting override values in '/tmp/clang++-e3eee6/libsycl-crt-0c2141.cubin' and 'llvm-link'
clang++: error: sycl-link command failed with exit code 1 (use -v to see invocation)
make[2]: *** [src_sycl/CMakeFiles/nbody_dpcpp.dir/build.make:200: /home/illya/Dev/CodeplayExamples/cuda-to-sycl-nbody-dpct-includes/nbody_dpcpp] Error 1
make[1]: *** [CMakeFiles/Makefile2:116: src_sycl/CMakeFiles/nbody_dpcpp.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

[rafbiels]

Hi @irudkin, the linker error has a workaround described here:
https://developer.codeplay.com/products/oneapi/nvidia/2023.0.0/guides/troubleshooting#linking-error-with-nvvm-reflect-ftz

[irudkin]

Can I suggest, it would be good to have this linking issue with nvvm-reflect-ftz mentioned in the readme.md build section (mentioning the version of oneAPI/DPCPP) for others who may run into this problem.

[irudkin]

The cmake scripts use dpcpp the compiler. Should the project be changed to use the Intel icpx compiler and so remove any "dpcpp is being depreciated" warnings?

[rafbiels]

Hi @irudkin, these are good suggestions. Let's follow up in #25 as these issues are not related to the DPCT headers which are addressed in this PR.