Author: Anastasia Stulova Date: 2021-01-08T13:45:59Z New Revision: 0ef2b68ff063164a83a37a2a363196d51b76ed8d
URL: https://github.com/llvm/llvm-project/commit/0ef2b68ff063164a83a37a2a363196d51b76ed8d DIFF: https://github.com/llvm/llvm-project/commit/0ef2b68ff063164a83a37a2a363196d51b76ed8d.diff LOG: [OpenCL] Documentation for experimental C++ libs Started a new doc section about the OpenCL experimental features and described ongoing work on C++ libraries e.g. type traits. Tags: #clang Differential Revision: https://reviews.llvm.org/D94188 Added: Modified: clang/docs/OpenCLSupport.rst Removed: ################################################################################ diff --git a/clang/docs/OpenCLSupport.rst b/clang/docs/OpenCLSupport.rst index 62ba890c3a95..b00a9ef41064 100644 --- a/clang/docs/OpenCLSupport.rst +++ b/clang/docs/OpenCLSupport.rst @@ -20,7 +20,7 @@ OpenCL Support Clang fully supports all OpenCL C versions from 1.1 to 2.0. Please refer to `Bugzilla -<https://bugs.llvm.org/buglist.cgi?component=OpenCL&list_id=172679&product=clang&resolution=--->`_ +<https://bugs.llvm.org/buglist.cgi?component=OpenCL&list_id=172679&product=clang&resolution=--->`__ for the most up to date bug reports. @@ -45,3 +45,57 @@ Missing features or with limited support - Initialization of objects in `__constant` address spaces is not guaranteed to work. - `addrspace_cast` operator is not supported. + +Experimental features +===================== + +Clang provides the following new WIP features for the developers to experiment +and provide early feedback or contribute with further improvements. +Feel free to contact us on `cfe-dev +<https://lists.llvm.org/mailman/listinfo/cfe-dev>`_ or via `Bugzilla +<https://bugs.llvm.org/>`__. + +C++ libraries for OpenCL +------------------------ + +There is ongoing work to support C++ standard libraries from `LLVM's libcxx +<https://libcxx.llvm.org/>`_ in OpenCL kernel code using C++ for OpenCL mode. + +It is currently possible to include `type_traits` from C++17 in the kernel +sources when the following clang extensions are enabled +``__cl_clang_function_pointers`` and ``__cl_clang_variadic_functions``, +see :doc:`LanguageExtensions` for more details. The use of non-conformant +features enabled by the extensions does not expose non-conformant behavior +beyond the compilation i.e. does not get generated in IR or binary. +The extension only appear in metaprogramming +mechanism to identify or verify the properties of types. This allows to provide +the full C++ functionality without a loss of portability. To avoid unsafe use +of the extensions it is recommended that the extensions are disabled directly +after the header include. + +**Example of Use**: + +The example of kernel code with `type_traits` is illustrated here. + +.. code-block:: c++ + + #pragma OPENCL EXTENSION __cl_clang_function_pointers : enable + #pragma OPENCL EXTENSION __cl_clang_variadic_functions : enable + #include <type_traits> + #pragma OPENCL EXTENSION __cl_clang_function_pointers : disable + #pragma OPENCL EXTENSION __cl_clang_variadic_functions : disable + + using sint_type = std::make_signed<unsigned int>::type; + + __kernel void foo() { + static_assert(!std::is_same<sint_type, unsigned int>::value); + } + +The possible clang invocation to compile the example is as follows: + + .. code-block:: console + + $ clang -cl-std=clc++ -I<path to libcxx checkout or installation>/include test.cl + +Note that `type_traits` is a header only library and therefore no extra +linking step against the standard libraries is required. _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
