Files
clang-p2996/libunwind/docs/BuildingLibunwind.rst
Louis Dionne fa1c077b41 [runtimes] Remove support for GCC-style 32 bit multilib builds
This patch removes the ability to build the runtimes in the 32 bit
multilib configuration, i.e. using -m32. Instead of doing this, one
should cross-compile the runtimes for the appropriate target triple,
like we do for all other triples.

As it stands, -m32 has several issues, which all seem to be related to
the fact that it's not well supported by the operating systems that
libc++ support. The simplest path towards fixing this is to remove
support for the configuration, which is also the best course of action
if there is little interest for keeping that configuration. If there
is a desire to keep this configuration around, we'll need to do some
work to figure out the underlying issues and fix them.

Differential Revision: https://reviews.llvm.org/D114473
2021-12-01 12:57:01 -05:00

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4.0 KiB
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.. _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 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_PROJECTS=libunwind [options] <path to llvm sources>``
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
It is sometimes beneficial to build outside of the LLVM tree. An out-of-tree
build would look like this:
.. code-block:: bash
$ 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
.. _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**: ``ON``
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_TARGET_TRIPLE:STRING
Target triple for cross compiling
.. option:: LIBUNWIND_GCC_TOOLCHAIN:PATH
GCC toolchain for cross compiling
.. option:: LIBUNWIND_SYSROOT
Sysroot for cross compiling
.. 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``.