Building libunwind¶

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:

Checkout LLVM, libunwind, and related projects:
- cd where-you-want-llvm-to-live
- git clone https://github.com/llvm/llvm-project.git
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> -DLLVM_ENABLE_RUNTIMES=libunwind [options] <llvm-monorepo>/runtimes
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.
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 https://llvm.org/svn/llvm-project/llvm/trunk llvm``
$ ``svn co https://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

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.

libunwind specific options ¶

LIBUNWIND_ENABLE_ASSERTIONS:BOOL¶

Default: ON

Toggle assertions independent of the build mode.

LIBUNWIND_ENABLE_PEDANTIC:BOOL¶

Default: ON

Compile with -Wpedantic.

LIBUNWIND_ENABLE_WERROR:BOOL¶

Default: ON

Compile with -Werror

LIBUNWIND_ENABLE_SHARED:BOOL¶

Default: ON

Build libunwind as a shared library.

LIBUNWIND_ENABLE_STATIC:BOOL¶

Default: ON

Build libunwind as a static archive.

LIBUNWIND_ENABLE_CROSS_UNWINDING:BOOL¶

Default: OFF

Enable cross-platform unwinding support.

LIBUNWIND_ENABLE_ARM_WMMX:BOOL¶

Default: OFF

Enable unwinding support for ARM WMMX registers.

LIBUNWIND_ENABLE_THREADS:BOOL¶

Default: ON

Build libunwind with threading support.

LIBUNWIND_INSTALL_LIBRARY_DIR:PATH¶

Default: lib${LIBUNWIND_LIBDIR_SUFFIX}

Path where built libunwind libraries should be installed. If a relative path, relative to CMAKE_INSTALL_PREFIX.

libunwind documentation