Fixed parser of OpenCL 3.0 for NVIDIA GPU

[redradist]

No description provided.

[densamoilov]

Can you please elaborate on the reasoning behind this PR?

[vpirogov]

@redradist,

Adding 3.0 to the list of OpenCL version makes sense. We are still looking for your comments on the rationale for remaining changes.

[redradist]

@vpirogov @densamoilov Because this code successfully detect version of OpenCL library, but this one with CMAKE_CHECK_SYMBOLS cannot, even with defined variables to include dirs and link libraries:

...

function(_FIND_OPENCL_VERSION)
  include(CheckSymbolExists)
  include(CMakePushCheckState)
  set(CMAKE_REQUIRED_QUIET ${OpenCL_FIND_QUIETLY})
  set(CMAKE_REQUIRED_INCLUDES ${OpenCL_INCLUDE_DIR})
  set(CMAKE_REQUIRED_LIBRARIES ${OpenCL_LIBRARY})

  CMAKE_PUSH_CHECK_STATE()
  foreach(VERSION "3_0" "2_2" "2_1" "2_0" "1_2" "1_1" "1_0")
    if(APPLE)
      CHECK_SYMBOL_EXISTS(
        CL_VERSION_${VERSION}
        "${OpenCL_INCLUDE_DIR}/Headers/cl.h"
        OPENCL_VERSION_${VERSION})
    else()
      CHECK_SYMBOL_EXISTS(
        CL_VERSION_${VERSION}
        "${OpenCL_INCLUDE_DIR}/CL/cl.h"
        OPENCL_VERSION_${VERSION})
    endif()

    message(STATUS "OPENCL_VERSION_${VERSION} = ${OPENCL_VERSION_${VERSION}}")

    if(OPENCL_VERSION_${VERSION})
      string(REPLACE "_" "." VERSION "${VERSION}")
      set(OpenCL_VERSION_STRING ${VERSION} PARENT_SCOPE)
      string(REGEX MATCHALL "[0-9]+" version_components "${VERSION}")
      list(GET version_components 0 major_version)
      list(GET version_components 1 minor_version)
      set(OpenCL_VERSION_MAJOR ${major_version} PARENT_SCOPE)
      set(OpenCL_VERSION_MINOR ${minor_version} PARENT_SCOPE)
      break()
    endif()
  endforeach()
  CMAKE_POP_CHECK_STATE()
endfunction()

...

For CL_VERSION_${VERSION} inside file /usr/include/CL/cl.h (not even in /usr/include/CL/cl_version.h), defines are empty ...
OPENCL_VERSION_${VERSION} is always empty, due to possible missed defines. There are ifdef instead of define with number.
Maybe due to this it cannot detection library version

[densamoilov]

(random place)

There are a few things that look suspicious to me:

• We didn't implement FindOpenCL.cmake module, we've taken it from CMake (see here) and it still uses CHECK_SYMBOL_EXISTS and the community seems to be fine with it
• The version macros are standardized by the OpenCL specification so if the macros are missing then it likely means that there is something wrong with the OpenCL implementation you use
• It should be fine to check cl.h header as it includes cl_version.h header and CHECK_SYMBOL_EXISTS does perform a preprocessing

Given all this, I think the issue you encounter is somewhere on your end.

[redradist]

@densamoilov Here is my OpenCL files for NVIDIA GPU:
cl_files.zip

It looks fine for me

[vpirogov]

Considering the discussion the best way forward is updating FindOpenCL.cmake from upstream.