Getting Started¶

On Mac OS, the easiest way to get this library is to link with -lSystem. However if you want to build tip-of-trunk from here (getting the bleeding edge), read on.

The basic steps needed to build libc++ are:

1. Checkout LLVM:

   • cd where-you-want-llvm-to-live
   • svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm

2. Checkout libunwind:

   • cd where-you-want-llvm-to-live
   • cd llvm/runtimes
   • svn co http://llvm.org/svn/llvm-project/libunwind/trunk libunwind

3. Configure and build libunwind:

   CMake is the only supported configuration system.

   Clang is the preferred compiler when building and using libunwind.

   • cd where you want to build llvm
   • mkdir build
   • cd build
   • cmake -G <generator> [options] <path to llvm sources>

   For more information about configuring libunwind see CMake Options.

   • make unwind — will build libunwind.
   • make check-unwind — will run the test suite.

   Shared and static libraries for libunwind should now be present in llvm/build/lib.

4. Optional: Install libunwind

   If your system already provides an unwinder, it is important to be careful not to replace it. Remember Use the CMake option CMAKE_INSTALL_PREFIX to select a safe place to install libunwind.

   • make install-unwind — Will install the libraries and the headers

It is sometimes beneficial to build outside of the LLVM tree. An out-of-tree build would look like this:

$ cd where-you-want-libunwind-to-live
$ # Check out llvm, and libunwind
$ ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm``
$ ``svn co http://llvm.org/svn/llvm-project/libunwind/trunk libunwind``
$ cd where-you-want-to-build
$ mkdir build && cd build
$ export CC=clang CXX=clang++
$ cmake -DLLVM_PATH=path/to/llvm \
        path/to/libunwind
$ make

CMake Options¶

Here are some of the CMake variables that are used often, along with a brief explanation and LLVM-specific notes. For full documentation, check the CMake docs or execute cmake --help-variable VARIABLE_NAME.

CMAKE_BUILD_TYPE:STRING

Sets the build type for make based generators. Possible values are Release, Debug, RelWithDebInfo and MinSizeRel. On systems like Visual Studio the user sets the build type with the IDE settings.

CMAKE_INSTALL_PREFIX:PATH

Path where LLVM will be installed if “make install” is invoked or the “INSTALL” target is built.

CMAKE_CXX_COMPILER:STRING

The C++ compiler to use when building and testing libunwind.