[DFT][CMake] Check CUDA support with portFFT before using it as a tar…

…get (oneapi-src#511)

* The portFFT backends targets Nvidia by default
* In some situations, this causes a failure whilst compiling (CUDA might not be installed)
* This checks the target is supported before use

This solves the issue in PR oneapi-src#495

.github/workflows/pr.yml

@@ -24,7 +24,7 @@ jobs:
  options: -DTARGET_DOMAINS=blas -DREF_BLAS_ROOT=${PWD}/lapack/install -DENABLE_PORTBLAS_BACKEND=ON -DENABLE_MKLCPU_BACKEND=OFF -DPORTBLAS_TUNING_TARGET=INTEL_CPU
  tests: '.*'
  - config: portFFT
- options: -DENABLE_PORTFFT_BACKEND=ON -DENABLE_MKLCPU_BACKEND=OFF -DTARGET_DOMAINS=dft -DCMAKE_CXX_FLAGS="-fsycl -fsycl-targets=spir64"
+ options: -DENABLE_PORTFFT_BACKEND=ON -DENABLE_MKLCPU_BACKEND=OFF -DTARGET_DOMAINS=dft
  tests: 'DFT/CT/.*ComputeTests_in_place_COMPLEX.COMPLEX_SINGLE_in_place_buffer.sizes_8_batches_1*'
  - config: MKL BLAS
  options: -DTARGET_DOMAINS=blas -DREF_BLAS_ROOT=${PWD}/lapack/install

cmake/FindCompiler.cmake

@@ -36,6 +36,9 @@ if(is_dpcpp)
  if(UNIX)
  set(UNIX_INTERFACE_COMPILE_OPTIONS -fsycl)
  set(UNIX_INTERFACE_LINK_OPTIONS -fsycl)
+ # Check if the Nvidia target is supported. PortFFT uses this for choosing default configuration.
+ check_cxx_compiler_flag("-fsycl -fsycl-targets=nvptx64-nvidia-cuda" dpcpp_supports_nvptx64)
+
  if(ENABLE_CURAND_BACKEND OR ENABLE_CUSOLVER_BACKEND)
  list(APPEND UNIX_INTERFACE_COMPILE_OPTIONS
  -fsycl-targets=nvptx64-nvidia-cuda -fsycl-unnamed-lambda)

src/dft/backends/portfft/CMakeLists.txt

@@ -36,7 +36,10 @@ if (IS_DPCPP AND UNIX AND NOT FOUND_TARGETS)
  set(TARGETS_LINK_OPTIONS -fsycl-unnamed-lambda)
 
  # spir64 must be last in the list due to a bug in dpcpp 2024.0.0
- set(TARGETS_TRIPLES "nvptx64-nvidia-cuda,spir64")
+ set(TARGETS_TRIPLES "spir64")
+ if(dpcpp_supports_nvptx64)
+ set(TARGETS_TRIPLES nvptx64-nvidia-cuda,${TARGETS_TRIPLES})
+ endif()
 
  if (NOT (HIP_TARGETS STREQUAL ""))
  set(TARGETS_TRIPLES amdgcn-amd-amdhsa,${TARGETS_TRIPLES})
@@ -45,6 +48,8 @@ if (IS_DPCPP AND UNIX AND NOT FOUND_TARGETS)
  else()
  message(WARNING "Can't enable hip backend, HIP_TARGETS has not been set.")
  endif()
+
+ message(STATUS "portFFT target triple set to ${TARGETS_TRIPLES}")
 
  list(APPEND TARGETS_COMPILE_OPTIONS -fsycl-targets=${TARGETS_TRIPLES})
  list(APPEND TARGETS_LINK_OPTIONS -fsycl-targets=${TARGETS_TRIPLES})