GPU CMake: Auto-detect ROCm even if CMake prefix path not set

Author: davidrohr

dependencies/FindO2GPU.cmake

@@ -198,15 +198,18 @@ endif()
 
 # Detect and enable HIP
 if(ENABLE_HIP)
-  if("$ENV{CMAKE_PREFIX_PATH}" MATCHES "rocm")
+  if(NOT "$ENV{CMAKE_PREFIX_PATH}" MATCHES "rocm" AND NOT CMAKE_PREFIX_PATH MATCHES "rocm" AND EXISTS "/opt/rocm/lib/cmake/")
+    list(APPEND CMAKE_PREFIX_PATH "/opt/rocm/lib/cmake")
+  endif()
+  if("$ENV{CMAKE_PREFIX_PATH}" MATCHES "rocm" OR CMAKE_PREFIX_PATH MATCHES "rocm")
     set(CMAKE_HIP_STANDARD ${CMAKE_CXX_STANDARD})
     set(CMAKE_HIP_STANDARD_REQUIRED TRUE)
     if(HIP_AMDGPUTARGET)
       set(AMDGPU_TARGETS "${HIP_AMDGPUTARGET}" CACHE STRING "AMD GPU targets to compile for" FORCE)
       set(GPU_TARGETS "${HIP_AMDGPUTARGET}" CACHE STRING "AMD GPU targets to compile for" FORCE)
       set(CMAKE_HIP_ARCHITECTURES "${HIP_AMDGPUTARGET}" CACHE STRING "AMD GPU targets to compile for" FORCE)
     endif()
-    set(TMP_ROCM_DIR_LIST $ENV{CMAKE_PREFIX_PATH})
+    set(TMP_ROCM_DIR_LIST "${CMAKE_PREFIX_PATH}:$ENV{CMAKE_PREFIX_PATH}")
     string(REPLACE ":" ";" TMP_ROCM_DIR_LIST "${TMP_ROCM_DIR_LIST}")
     list(FILTER TMP_ROCM_DIR_LIST INCLUDE REGEX rocm)
     list(POP_FRONT TMP_ROCM_DIR_LIST TMP_ROCM_DIR)