SPIR-V generator/Clang Installation Instructions

These instructions describe how to build, install and operate SPIR-V generator Clang.

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Step 1: Organization

SPIR generator/Clang is designed to be built as part of an LLVM build.

SPIR generator/Clang is based on LLVM/Clang version 3.6.

The LLVM source code with SPIR-V support can be downloaded from https://github.com/KhronosGroup/SPIRV-LLVM.git:

  git clone -b khronos/spirv-3.6.1 https://github.com/KhronosGroup/SPIRV-LLVM.git llvm

Assuming that the LLVM source code is located at $LLVM_SRC_ROOT, then the clang source code should be installed as: $LLVM_SRC_ROOT/tools/clang.

The directory is not required to be called clang, but doing so will allow the LLVM build system to automatically recognize it and build it along with LLVM.

  cd $LLVM_SRC_ROOT/tools
  git clone -b spirv-1.1 https://github.com/KhronosGroup/SPIR clang

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Step 2: Configure and Build LLVM

Configure and build your copy of LLVM (see $LLVM_SRC_ROOT/GettingStarted.html for more information).

Assuming you installed clang at $LLVM_SRC_ROOT/tools/clang then Clang will automatically be built with LLVM. Otherwise, run make in the Clang source directory to build Clang.

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Step 3: (Optional) Verify Your Build

It is a good idea to run the Clang tests to make sure your build works correctly. From inside the Clang build directory, run make check-all to run the tests.

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Step 4: Install Clang

If you wish to run Clang from the generated binary directory, you may skip this section.

From inside the Clang build directory, run make install to install the Clang compiler and header files into the prefix directory selected when LLVM was configured.

The Clang compiler is available as clang and clang++. It supports a gcc like command line interface. See the man page for clang (installed into $prefix/share/man/man1) for more information.

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Step 5: OpenCL C++ standard library

Clone the OpenCL C++ standard libary to location where you installed Clang

  git clone https://github.com/KhronosGroup/libclcxx.git master

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Step 6: Creating SPIR-V binaries

To create a SPIR-V binary from a valid OpenCL-C++ file (.cl), use the following command lines:

  clang -cc1 -emit-spirv -triple <triple> -cl-std=c++ -I <libclcxx dir> -x cl -o <output> <input> #For OpenCL C++
  clang -cc1 -emit-spirv -triple <triple> -cl-std=<CLversion> -include opencl.h -x cl -o <output> <input> #For OpenCL C

Notes:

• <triple>: for 32 bit SPIR-V use spir-unknown-unknown, for 64 bit SPIR-V use spir64-unknown-unknown.
• -D: to enable support for extension. e.g. -Dcl_khr_mipmap_image compile option will enable mipmap support.
• -cl-fp16-enable: to enable half support and define cl_khr_fp16
• -cl-fp64-enable: to enable double support and define cl_khr_fp64
• -O: -O0 (default) is the only tested option value at the moment. It's assumed by design that all optimizations are executed by SPIR-V consumer
• <libclcxx dir>: path to include directory from libclcxx (https://github.com/KhronosGroup/libclcxx) .

  clang -cc1 -emit-spirv -triple=spir-unknown-unknown -cl-std=c++ -I include kernel.cl -o kernel.spv #For OpenCL C++
  clang -cc1 -emit-spirv -triple=spir-unknown-unknown -cl-std=CL2.0 -include opencl.h kernel.cl -o kernel.spv #For OpenCL C

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Reporting issues

Bugs/feature requests can be filed via github or Khronos Bugzilla bug tracker.