Building SimEng


Building SimEng requires CMake and a compiler that supports C++17.


  1. Obtain the source code using git:
git clone
  1. Configure with CMake, specifying the path to your desired installation directory if necessary:
cd SimEng
cmake -B build -S .
        -DCMAKE_BUILD_TYPE={Release, Debug, RelWithDebInfo, MinSizeRel}
        -DSIMENG_ENABLE_TESTS={ON, OFF} #Defaults to OFF

With this configuration, the build files will be generated in a directory called “build”.

  1. The SimEng test suites depend on a selection of LLVM libraries. Building this dependency can take a while, therefore, the use of prebuilt LLVM libraries is supported. The following CMake configuration flags should be set to enable this:

    -DLLVM_DIR=<llvm_library_directory> # directory of LLVM libraries as CMake targets


More information about the LLVM_DIR value can be found here.


LLVM versions greater than 12 or less than 9 are not supported. We’d recommend using LLVM 12 where possible.

  1. Two additional flags are available when building SimEng. Firstly is -DSIMENG_SANITIZE={ON, OFF} which adds a selection of sanitisation compilation flags (primarily used during the development of the framework). Secondly is -SIMENG_OPTIMIZE={ON, OFF} which attempts to optimise the framework’s compilation for the host machine through a set of compiler flags and options.

We recommend using the Ninja build system for faster builds, especially if not using pre-built LLVM libraries. After installation, it can be enabled through the addition of the -GNinja flag in the above CMake build command.

  1. Once configured, use cmake --build build or whichever generator you have selected for CMake to build. Append the -j{Num_Cores} flag to build in parallel, keep in mind that building without a linked external LLVM library usually has very high (1.5GB per core) memory requirements.
  2. (Optional) Run cmake --build build --target test to run the SimEng regression tests and unit tests. Please report any test failures as a GitHub issue.
  3. Finally, run cmake --build build --target install to install SimEng to the directory specified with CMake.