.. _BuildingLibunwind:

================== Building libunwind

.. contents:: :local:

.. _build instructions:

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 libunwind 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 :ref: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

.. _CMake Options:

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.

.. _libunwind-specific options:

libunwind specific options

.. option:: LIBUNWIND_ENABLE_ASSERTIONS:BOOL

Default: ON

Toggle assertions independent of the build mode.

.. option:: LIBUNWIND_ENABLE_PEDANTIC:BOOL

Default: ON

Compile with -Wpedantic.

.. option:: LIBUNWIND_ENABLE_WERROR:BOOL

Default: OFF

Compile with -Werror

.. option:: LIBUNWIND_ENABLE_SHARED:BOOL

Default: ON

Build libunwind as a shared library.

.. option:: LIBUNWIND_ENABLE_STATIC:BOOL

Default: ON

Build libunwind as a static archive.

.. option:: LIBUNWIND_ENABLE_CROSS_UNWINDING:BOOL

Default: OFF

Enable cross-platform unwinding support.

.. option:: LIBUNWIND_ENABLE_ARM_WMMX:BOOL

Default: OFF

Enable unwinding support for ARM WMMX registers.

.. option:: LIBUNWIND_ENABLE_THREADS:BOOL

Default: ON

Build libunwind with threading support.

.. option:: 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.