opencl-clang is a thin wrapper library around clang. The library has OpenCL-oriented API and is capable to compile OpenCL C kernels to SPIR-V modules.
Source code in this repo can be built in different manners:
- in-tree as an LLVM project
- out-of-tree using pre-built LLVM
Before the build all dependencies must be downloaded and laid out as follows:
<workspace>
|-- llvm
|-- clang
|-- SPIRV-LLVM-Translator
`-- opencl-clang
This can be done using the following commands:
cd <workspace>
git clone https://github.com/llvm/llvm-project.git .
git clone https://github.com/KhronosGroup/SPIRV-LLVM-Translator.git
git clone https://github.com/intel/opencl-clang.git
Then we need to create a build directory and run the build:
export OCL_CLANG_WS=<workspace>
cd $OCL_CLANG_WS
mkdir build && cd build
cmake -DLLVM_TARGETS_TO_BUILD="X86" -DLLVM_ENABLE_PROJECTS="clang" \
-DLLVM_EXTERNAL_PROJECTS="llvm-spirv;opencl-clang" \
-DLLVM_EXTERNAL_LLVM_SPIRV_SOURCE_DIR="$OCL_CLANG_WS/SPIRV-LLVM-Translator" \
-DLLVM_EXTERNAL_OPENCL_CLANG_SOURCE_DIR="$OCL_CLANG_WS/opencl-clang" \
-DCMAKE_BUILD_TYPE=Release $OCL_CLANG_WS/llvm
make opencl-clang -j`nproc`
For sanity check of the build please run make check-clang
and
make check-llvm-spirv
To build opencl-clang as a standalone project, you need to obtain pre-built LLVM and SPIR-V Translator libraries. Note: currently this kind of build is supported on Linux only.
If opencl-clang is used as part of another CMake project, you will need to define OPENCL_CLANG_BUILD_EXTERNAL
.
Integration with pre-built LLVM is done using standard find_package
way as
documented in Embedding LLVM in your project.
Commands to checkout sources and build:
cd <workspace>
git clone https://github.com/intel/opencl-clang.git
mkdir build && cd build
cmake ../opencl-clang
make all -j`nproc`
By default, opencl-clang's cmake script is searching for LLVM which is built
based on the latest verion of current branch. You can override target version of
LLVM by using the PREFERRED_LLVM_VERSION
cmake option:
Example:
cmake -DPREFERRED_LLVM_VERSION="19.0" ../opencl-clang
If LLVM is installed somewhere in custom (non-system directories) location, you
could point to it using the LLVM_DIR
cmake option. Note: You need to
specify the path to a directory containing the LLVMConfig.cmake
file.
This file is available in two different locations.
<INSTALL_PREFIX>/lib/cmake/llvm/LLVMConfig.cmake
where<INSTALL_PREFIX>
is the install prefix of an installed version of LLVM. On Linux this is typically/usr/lib/cmake/llvm/LLVMConfig.cmake
.<LLVM_BUILD_ROOT>/lib/cmake/llvm/LLVMConfig.cmake
where<LLVM_BUILD_ROOT>
is the root of the LLVM build tree. Note: this is only available when building LLVM with CMake.
Example:
cmake -DLLVM_DIR=/path/to/installed/llvm/lib/cmake/llvm ../opencl-clang
By default, opencl-clang's cmake script assumes that SPIR-V Translator library is built as part of LLVM, installed in the same place and libLLVMSPIRVLib is linked into libLLVM.
If that is not true for you, you can override this: firstly, you need to set
LLVMSPIRV_INCLUDED_IN_LLVM
cmake option to OFF
. Then you need to specify
directory where SPIR-V Translator is installed by using SPIRV_TRANSLATOR_DIR
cmake option.
Example:
cmake -DLLVMSPIRV_INCLUDED_IN_LLVM=OFF -DSPIRV_TRANSLATOR_DIR=/path/to/installed/spirv/translator ../opencl-clang
There is a known issue (linker crash) for this kind of build on Ubuntu 16.04 Xenial. In this case the following cmake option should fix it:
-DLLVM_NO_DEAD_STRIP=ON
Installation directory of SPIR-V Translator is expected to contain the following files:
<installation_dir>
|-- include
| `-- LLVMSPIRVLib
| `-- LLVMSPIRVLib.h
`-- lib64
`-- libLLVMSPIRVLib.so
Please submit a pull request to contribute.
Please follow LLVM coding standards
Please submit an issue