Clarify HIP usage (#540)

CMakeLists.txt

@@ -108,12 +108,8 @@ if(GPU_TARGETS STREQUAL "all")
   set(GPU_TARGETS "${DEFAULT_AMDGPU_TARGETS}" CACHE STRING "GPU architectures to compile for" FORCE)
 endif()
 
-if(NOT WIN32)
-  include(cmake/VerifyCompiler.cmake)
-else()
-  list(APPEND CMAKE_PREFIX_PATH ${ROCM_PATH} $ENV{ROCM_PATH}/hip $ENV{ROCM_PATH}/llvm)
-  find_package(hip REQUIRED CONFIG PATHS ${HIP_DIR} $ENV{ROCM_PATH})
-endif()
+# Verify the compiler settings and include the HIP CMake package
+include(cmake/VerifyCompiler.cmake)
 
 # Build option to disable -Werror
 option(DISABLE_WERROR "Disable building with Werror" ON)

cmake/VerifyCompiler.cmake

@@ -20,22 +20,22 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-list(APPEND CMAKE_PREFIX_PATH $ENV{ROCM_PATH} $ENV{ROCM_PATH}/hip)
+list(APPEND CMAKE_PREFIX_PATH $ENV{ROCM_PATH} $ENV{ROCM_PATH}/hip $ENV{ROCM_PATH})
 if(CMAKE_CXX_COMPILER MATCHES ".*/nvcc$" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    find_package(hip QUIET CONFIG PATHS $ENV{ROCM_PATH})
-    if(NOT hip_FOUND)
-        find_package(HIP REQUIRED)
-    endif()
+    # Compiling for CUDA
+    find_package(hip REQUIRED CONFIG PATHS $ENV{ROCM_PATH})
     if((HIP_COMPILER STREQUAL "clang"))
        # TODO: The HIP package on NVIDIA platform is incorrect at few versions
        set(HIP_COMPILER "nvcc" CACHE STRING "HIP Compiler" FORCE)
     endif()
 else()
-  message("Looking in $ENV{ROCM_PATH}...")
-  find_package(hip REQUIRED CONFIG PATHS $ENV{ROCM_PATH})
+    # compiling for ROCm
+    message("Looking in $ENV{ROCM_PATH}...")
+    find_package(hip REQUIRED CONFIG PATHS $ENV{ROCM_PATH})
 endif()
 
 if(HIP_COMPILER STREQUAL "nvcc")
+    # NVCC requires some additional setup
     include(SetupNVCC)
 elseif(HIP_COMPILER STREQUAL "clang")
     if(NOT (CMAKE_CXX_COMPILER MATCHES ".*hipcc$" OR CMAKE_CXX_COMPILER MATCHES ".*clang\\+\\+"))