The OpenCilk runtime system

This repository contains the source code of the OpenCilk runtime system. This library is intended to be used with the OpenCilk compiler and can either be built together with the compiler or as a standalone library.

Building a standalone copy of the OpenCilk runtime

These instructions assume that you are building the OpenCilk runtime system using the OpenCilk compiler.

Using Makefiles

1. If necessary, update the COMPILER_BASE variable in config.mk to point to the directory containing the OpenCilk compiler binaries, e.g., /path/to/opencilk-project/build/bin/. When it executes clang and other OpenCilk compiler binaries, the Makefile prepends this path to those binaries.
2. Run make.

To clean the build, run make clean.

Using CMake

1. Make a build directory at the top level and enter it:

   mkdir build
   cd build

2. Configure CMake. Make sure to specify CMAKE_C_COMPILER, CMAKE_CXX_COMPILER, and LLVM_CMAKE_DIR to point to the corresponding build or installation of the OpenCilk compiler binaries. In addition, set CMAKE_BUILD_TYPE to specify the build type, such as:

   • Debug, for an unoptimized build with all assertions enabled (default);
   • Release, for an fully optimized build with assertions disabled; or
   • RelWithDebInfo, to enable some optimizations and assertions.

   cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=/path/to/opencilk-project/build/bin/clang -DCMAKE_CXX_COMPILER=/path/to/opencilk-project/build/bin/clang++ -DLLVM_CMAKE_DIR=/path/to/opencilk-project/build ../

3. Build the runtime:

   cmake --build . -- -j<number of build threads>

To clean the build, run cmake --build . --target clean from the build directory.

Using a standalone build of the OpenCilk runtime

The OpenCilk compiler accepts the flag --opencilk-resource-dir=/path/to/cheetah to specify where to find all relevant OpenCilk runtime files, including the runtime library, the bitcode ABI file, and associated header files. This resource directory should have include/ and lib/<target triple> as subdirectories. For example, if you built the standalone OpenCilk runtime using CMake, then pass the flag --opencilk-resource-dir=/path/to/cheetah/build to the OpenCilk compiler to link against that standalone build as follows:

/path/to/opencilk-project/build/bin/clang -o fib fib.c -fopencilk -O3 --opencilk-resource-dir=/path/to/cheetah/build