[llvm] [Offload] Rework compiling device code for unit test suites (PR #144776)

[Joseph Huber via llvm-commits]

================
@@ -1,6 +1,72 @@
 add_custom_target(OffloadUnitTests)
 set_target_properties(OffloadUnitTests PROPERTIES FOLDER "Tests/UnitTests")
 
+function(add_offload_test_device_code test_filename test_name)
+  set(SRC_PATH ${CMAKE_CURRENT_SOURCE_DIR}/${test_filename})
+  set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+
+  # Try to build with support for NVPTX devices.
+  if("cuda" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
+    find_package(CUDAToolkit QUIET)
+    if(CUDAToolkit_FOUND)
+      get_filename_component(cuda_path "${CUDAToolkit_BIN_DIR}" DIRECTORY ABSOLUTE)
+    endif()
+    check_cxx_compiler_flag(
+      "--target=nvptx64-nvidia-cuda -march=native --cuda-path=${cuda_path}" PLATFORM_HAS_NVPTX)
+
+    if(PLATFORM_HAS_NVPTX)
+      set(nvptx_arch "native")
+    elseif(OFFLOAD_TESTS_FORCE_NVIDIA_ARCH)
+      set(nvptx_arch "${OFFLOAD_TESTS_FORCE_NVIDIA_ARCH}")
+    endif()
+
+    if(nvptx_arch AND CUDAToolkit_FOUND)
+      set(output_file "${CMAKE_CURRENT_BINARY_DIR}/${test_name}.nvptx64.bin")
+      add_custom_command(
+        OUTPUT ${output_file}
+        COMMAND ${CMAKE_C_COMPILER}
+        --target=nvptx64-nvidia-cuda -march=${nvptx_arch}
+        -nogpulib --cuda-path=${CUDA_ROOT} -flto ${ARGN}
+        -c ${SRC_PATH} -o ${output_file}
+        DEPENDS ${SRC_PATH}
+      )
+      add_custom_target(${test_name}.nvptx64 DEPENDS ${output_file})
+    endif()
+  endif()
+
+  # Try to build with support for AMDGPU devices.
+  if("amdgpu" IN_LIST LIBOMPTARGET_PLUGINS_TO_BUILD)
+    check_cxx_compiler_flag("--target=amdgcn-amd-amdhsa -mcpu=native" PLATFORM_HAS_AMDGPU)
+
+    if(PLATFORM_HAS_AMDGPU)
+      set(amdgpu_arch "native")
+    elseif(OFFLOAD_TESTS_FORCE_AMDGPU_ARCH)
+      set(amdgpu_arch "${OFFLOAD_TESTS_FORCE_AMDGPU_ARCH}")
+    endif()
----------------
jhuber6 wrote:

Good catch, I should reverse these.

https://github.com/llvm/llvm-project/pull/144776