Install LLVM

Download LLVM from github

git clone https://github.com/llvm/llvm-project.git

Config and build LLVM and Clang

• cd llvm-project

• mkdir build

• cd build

• cmake -G <generator> [options] ../llvm

  For example, if you want to build only LLVM and Clang on Linux with release version, you can run:

  • cmake -DLLVM_ENABLE_PROJECTS=clang -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release ../llvm-project/llvm/

  If you want to build with libcxx and libcxxabi, you can run:

  • cmake -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi" -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release ../llvm-project/llvm/

  Some common build system generators are:

  • Ninja --- for generating Ninja build files. Most llvm developers use Ninja.
  • Unix Makefiles --- for generating make-compatible parallel makefiles.
  • Visual Studio --- for generating Visual Studio projects and solutions.
  • Xcode --- for generating Xcode projects.

  Some Common options:

  • -DLLVM_ENABLE_PROJECTS='...' --- semicolon-separated list of the LLVM sub-projects you'd like to additionally build. Can include any of: clang, clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld, polly, or debuginfo-tests.

    For example, to build LLVM, Clang, libcxx, and libcxxabi, use -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi".

  • -DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the full path name of where you want the LLVM tools and libraries to be installed (default /usr/local).

  • -DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug.

  • -DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).

• cmake --build . [-- [options] <target>] or your build system specified above directly.

  • The default target (i.e. ninja or make) will build all of LLVM.

  • The check-all target (i.e. ninja check-all) will run the regression tests to ensure everything is in working order.

  • CMake will generate targets for each tool and library, and most LLVM sub-projects generate their own check-<project> target.

  • Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for make, use the option -j NNN, where NNN is the number of parallel jobs, e.g. the number of CPUs you have.