forked from OSchip/llvm-project
[OpenCL][Doc] Misc improvements related to SPIR-V support.
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Anastasia Stulova
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@ -25,9 +25,19 @@ Clang also supports :ref:`the C++ for OpenCL kernel language <cxx_for_opencl_imp
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There are also other :ref:`new and experimental features <opencl_experimenal>`
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available.
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For general issues and bugs with OpenCL in clang refer to `the GitHub issue
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list
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<https://github.com/llvm/llvm-project/issues?q=is%3Aopen+is%3Aissue+label%3Aopencl>`__.
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Missing features or with limited support
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========================================
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- For general issues and bugs with OpenCL in clang refer to `the GitHub issue
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list
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<https://github.com/llvm/llvm-project/issues?q=is%3Aopen+is%3Aissue+label%3Aopencl>`__.
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- Command-line flag :ref:`-cl-ext <opencl_cl_ext>` (used to override extensions/
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features supported by a target) is missing support of some functionality i.e. that is
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implemented fully through libraries (see :ref:`library-based features and
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extensions <opencl_ext_libs>`).
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Internals Manual
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================
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@ -213,18 +223,22 @@ indicating the presence of the extension should be added to clang.
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The default flow for adding a new extension into the frontend is to
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modify `OpenCLExtensions.def
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<https://github.com/llvm/llvm-project/blob/main/clang/include/clang/Basic/OpenCLExtensions.def>`_
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<https://github.com/llvm/llvm-project/blob/main/clang/include/clang/Basic/OpenCLExtensions.def>`__,
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containing the list of all extensions and optional features supported by
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the frontend.
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This will add the macro automatically and also add a field in the target
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options ``clang::TargetOptions::OpenCLFeaturesMap`` to control the exposure
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of the new extension during the compilation.
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Note that by default targets like `SPIR` or `X86` expose all the OpenCL
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Note that by default targets like `SPIR-V`, `SPIR` or `X86` expose all the OpenCL
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extensions. For all other targets the configuration has to be made explicitly.
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Note that the target extension support performed by clang can be overridden
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with :ref:`-cl-ext <opencl_cl_ext>` command-line flags.
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.. _opencl_ext_libs:
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**Library functionality**
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If an extension adds functionality that does not modify standard language
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@ -239,7 +253,9 @@ for more details refer to
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:ref:`the section on the OpenCL Header <opencl_header>`. The macros indicating
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the presence of such extensions can be added in the standard header files
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conditioned on target specific predefined macros or/and language version
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predefined macros.
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predefined macros (see `feature/extension preprocessor macros defined in
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opencl-c-base.h
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<https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/opencl-c-base.h>`__).
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**Pragmas**
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@ -336,8 +352,9 @@ user should specify both (extension and feature) in command-line flag:
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.. code-block:: console
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$ clang -cc1 -cl-std=CL3.0 -cl-ext=+cl_khr_fp64,+__opencl_c_fp64 ...
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$ clang -cc1 -cl-std=CL3.0 -cl-ext=-cl_khr_fp64,-__opencl_c_fp64 ...
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$ clang -cl-std=CL3.0 -cl-ext=+cl_khr_fp64,+__opencl_c_fp64 ...
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$ clang -cl-std=CL3.0 -cl-ext=-cl_khr_fp64,-__opencl_c_fp64 ...
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OpenCL C 3.0 Implementation Status
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@ -3065,7 +3065,7 @@ Compiling to bitcode can be done as follows:
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This will produce a file `test.bc` that can be used in vendor toolchains
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to perform machine code generation.
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Note that if compiled to bitcode for generic targets such as SPIR,
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Note that if compiled to bitcode for generic targets such as SPIR/SPIR-V,
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portable IR is produced that can be used with various vendor
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tools as well as open source tools such as `SPIRV-LLVM Translator
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<https://github.com/KhronosGroup/SPIRV-LLVM-Translator>`_
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@ -3073,15 +3073,18 @@ to produce SPIR-V binary. More details are provided in `the offline
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compilation from OpenCL kernel sources into SPIR-V using open source
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tools
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<https://github.com/KhronosGroup/OpenCL-Guide/blob/main/chapters/os_tooling.md>`_.
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From clang 14 onwards SPIR-V can be generated directly as detailed in
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:ref:`the SPIR-V support section <spir-v>`.
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Clang currently supports OpenCL C language standards up to v2.0. Clang mainly
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supports full profile. There is only very limited support of the embedded
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profile.
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Starting from clang 9 a C++ mode is available for OpenCL (see
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From clang 9 a C++ mode is available for OpenCL (see
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:ref:`C++ for OpenCL <cxx_for_opencl>`).
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OpenCL v3.0 support is complete but it remains in experimental state, see more
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details about the experimental features in :doc:`OpenCLSupport` page.
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details about the experimental features and limitations in :doc:`OpenCLSupport`
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page.
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OpenCL Specific Options
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-----------------------
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@ -3137,7 +3140,7 @@ Example disabling double support for the 64-bit SPIR-V target:
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.. code-block:: console
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$ clang -target spirv64 -cl-ext=-cl_khr_fp64 test.cl
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$ clang -c -target spirv64 -cl-ext=-cl_khr_fp64 test.cl
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Enabling all extensions except double support in R600 AMD GPU can be done using:
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@ -3214,8 +3217,6 @@ Generic Targets
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however :option:`-cl-ext` flag can be used to toggle individual extensions and
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features.
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.. _opencl_header:
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OpenCL Header
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@ -3427,6 +3428,7 @@ Example of use:
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.. code-block:: console
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clang -cl-std=clc++1.0 test.clcpp
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clang -cl-std=clc++ -c -target spirv64 test.cl
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By default, files with ``.clcpp`` extension are compiled with the C++ for
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@ -3640,7 +3642,7 @@ To generate SPIR-V binaries, Clang uses the external ``llvm-spirv`` tool from th
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Prior to the generation of SPIR-V binary with Clang, ``llvm-spirv``
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should be built or installed. Please refer to `the following instructions
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<https://github.com/KhronosGroup/SPIRV-LLVM-Translator#build-instructions>`_
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for more details. Clang will expects the ``llvm-spirv`` executable to
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for more details. Clang will expect the ``llvm-spirv`` executable to
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be present in the ``PATH`` environment variable. Clang uses ``llvm-spirv``
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with `the widely adopted assembly syntax package
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<https://github.com/KhronosGroup/SPIRV-LLVM-Translator/#build-with-spirv-tools>`_.
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@ -3692,6 +3694,10 @@ installation instructions
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$ clang -target spirv64 test1.cl test2.cl
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More information about the SPIR-V target settings and supported versions of SPIR-V
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format can be found in `the SPIR-V target guide
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<https://llvm.org/docs/SPIRVUsage.html>`__.
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.. _clang-cl:
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clang-cl
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