OpenMP: Correctly query location for amdgpu-arch

[arsenm]

Summary

This was trying to figure out the build path for amdgpu-arch, and
making assumptions about where it is which were not working on my
system. Whether a standalone build or not, we should have a proper
imported target to get the location from.

[JonChesterfield]

Building locally to convince myself this works, back shortly

[JonChesterfield]

LG, thanks!

[arsenm]

935abeaace123e5f11792a5175079d974d0a0be8

openmp/libomptarget/plugins/amdgpu/CMakeLists.txt

target_link_libraries(
   ${LIBOMPTARGET_DEP_LIBRARIES}
   ${CMAKE_DL_LIBS}
   ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
   ${OPENMP_PTHREAD_LIB}
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports"
   ${LDFLAGS_UNDEFINED}
   )
 
-if (LLVM_BINARY_DIR)
-  # for in-tree build using LLVM_ENABLE_RUNTIMES
-  set(AMDGPU_ARCH_TOOL "${LLVM_BINARY_DIR}/bin/amdgpu-arch")
-elseif (OPENMP_LLVM_TOOLS_DIR)
-  set(AMDGPU_ARCH_TOOL "${OPENMP_LLVM_TOOLS_DIR}/amdgpu-arch")
-else()
-  set(AMDGPU_ARCH_TOOL "amdgpu-arch")
-endif()
-
 # in case of amdgcn, skip running tests if amdgpu-arch was not built or fails
-if (NOT EXISTS "${AMDGPU_ARCH_TOOL}")
+if (NOT TARGET amdgpu-arch)
   libomptarget_say("Not generating amdgcn test targets as amdgpu-arch is not found")
   return()
 endif()
 
-execute_process(COMMAND "${AMDGPU_ARCH_TOOL}" RESULT_VARIABLE amdgpu_arch_result
+get_property(AMDGPU_ARCH_COMMAND TARGET amdgpu-arch PROPERTY LOCATION)
+
+execute_process(COMMAND ${AMDGPU_ARCH_COMMAND} RESULT_VARIABLE amdgpu_arch_result
                                                OUTPUT_VARIABLE amdgpu_arch_output)
 if (${amdgpu_arch_result})
   libomptarget_say("Not generating amdgcn test targets as amdgpu-arch exited with ${amdgpu_arch_result}")
-  return()
-endif()
-
+else()
   # Report to the parent scope that we are building a plugin for amdgpu
   set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} amdgcn-amd-amdhsa" PARENT_SCOPE)
+endif()
+