blob: 8459081fb8b3118b6f736850e317807e51f1ce7b [file] [log] [blame]
Building LLVM with CMake
.. contents::
`CMake <>`_ is a cross-platform build-generator tool. CMake
does not build the project, it generates the files needed by your build tool
(GNU make, Visual Studio, etc) for building LLVM.
If you are really anxious about getting a functional LLVM build, go to the
`Quick start`_ section. If you are a CMake novice, start on `Basic CMake usage`_
and then go back to the `Quick start`_ once you know what you are doing. The
`Options and variables`_ section is a reference for customizing your build. If
you already have experience with CMake, this is the recommended starting point.
.. _Quick start:
Quick start
We use here the command-line, non-interactive CMake interface.
#. `Download <>`_ and install
CMake. Version 2.8 is the minimum required.
#. Open a shell. Your development tools must be reachable from this shell
through the PATH environment variable.
#. Create a directory for containing the build. It is not supported to build
LLVM on the source directory. cd to this directory:
.. code-block:: console
$ mkdir mybuilddir
$ cd mybuilddir
#. Execute this command on the shell replacing `path/to/llvm/source/root` with
the path to the root of your LLVM source tree:
.. code-block:: console
$ cmake path/to/llvm/source/root
CMake will detect your development environment, perform a series of test and
generate the files required for building LLVM. CMake will use default values
for all build parameters. See the `Options and variables`_ section for
fine-tuning your build
This can fail if CMake can't detect your toolset, or if it thinks that the
environment is not sane enough. On this case make sure that the toolset that
you intend to use is the only one reachable from the shell and that the shell
itself is the correct one for you development environment. CMake will refuse
to build MinGW makefiles if you have a POSIX shell reachable through the PATH
environment variable, for instance. You can force CMake to use a given build
tool, see the `Usage`_ section.
.. _Basic CMake usage:
.. _Usage:
Basic CMake usage
This section explains basic aspects of CMake, mostly for explaining those
options which you may need on your day-to-day usage.
CMake comes with extensive documentation in the form of html files and on the
cmake executable itself. Execute ``cmake --help`` for further help options.
CMake requires to know for which build tool it shall generate files (GNU make,
Visual Studio, Xcode, etc). If not specified on the command line, it tries to
guess it based on you environment. Once identified the build tool, CMake uses
the corresponding *Generator* for creating files for your build tool. You can
explicitly specify the generator with the command line option ``-G "Name of the
generator"``. For knowing the available generators on your platform, execute
.. code-block:: console
$ cmake --help
This will list the generator's names at the end of the help text. Generator's
names are case-sensitive. Example:
.. code-block:: console
$ cmake -G "Visual Studio 9 2008" path/to/llvm/source/root
For a given development platform there can be more than one adequate
generator. If you use Visual Studio "NMake Makefiles" is a generator you can use
for building with NMake. By default, CMake chooses the more specific generator
supported by your development environment. If you want an alternative generator,
you must tell this to CMake with the ``-G`` option.
.. todo::
Explain variables and cache. Move explanation here from #options section.
.. _Options and variables:
Options and variables
Variables customize how the build will be generated. Options are boolean
variables, with possible values ON/OFF. Options and variables are defined on the
CMake command line like this:
.. code-block:: console
$ cmake -DVARIABLE=value path/to/llvm/source
You can set a variable after the initial CMake invocation for changing its
value. You can also undefine a variable:
.. code-block:: console
$ cmake -UVARIABLE path/to/llvm/source
Variables are stored on the CMake cache. This is a file named ``CMakeCache.txt``
on the root of the build directory. Do not hand-edit it.
Variables are listed here appending its type after a colon. It is correct to
write the variable and the type on the CMake command line:
.. code-block:: console
$ cmake -DVARIABLE:TYPE=value path/to/llvm/source
Frequently-used CMake variables
Here are listed 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``.
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.
Path where LLVM will be installed if "make install" is invoked or the
"INSTALL" target is built.
Extra suffix to append to the directory where libraries are to be
installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
to install libraries to ``/usr/lib64``.
Extra flags to use when compiling C source files.
Extra flags to use when compiling C++ source files.
Flag indicating is shared libraries will be built. Its default value is
OFF. Shared libraries are not supported on Windows and not recommended in the
other OSes.
.. _LLVM-specific variables:
LLVM-specific variables
Semicolon-separated list of targets to build, or *all* for building all
targets. Case-sensitive. Defaults to *all*. Example:
Build LLVM tools. Defaults to ON. Targets for building each tool are generated
in any case. You can build an tool separately by invoking its target. For
example, you can build *llvm-as* with a makefile-based system executing *make
llvm-as* on the root of your build directory.
Generate build targets for the LLVM tools. Defaults to ON. You can use that
option for disabling the generation of build targets for the LLVM tools.
Build LLVM examples. Defaults to OFF. Targets for building each example are
generated in any case. See documentation for *LLVM_BUILD_TOOLS* above for more
Generate build targets for the LLVM examples. Defaults to ON. You can use that
option for disabling the generation of build targets for the LLVM examples.
Build LLVM unit tests. Defaults to OFF. Targets for building each unit test
are generated in any case. You can build a specific unit test with the target
*UnitTestNameTests* (where at this time *UnitTestName* can be ADT, Analysis,
ExecutionEngine, JIT, Support, Transform, VMCore; see the subdirectories of
*unittests* for an updated list.) It is possible to build all unit tests with
the target *UnitTests*.
Generate build targets for the LLVM unit tests. Defaults to ON. You can use
that option for disabling the generation of build targets for the LLVM unit
Append version control revision info (svn revision number or Git revision id)
to LLVM version string (stored in the PACKAGE_VERSION macro). For this to work
cmake must be invoked before the build. Defaults to OFF.
Build with threads support, if available. Defaults to ON.
Enables code assertions. Defaults to OFF if and only if ``CMAKE_BUILD_TYPE``
is *Release*.
Add the ``-fPIC`` flag for the compiler command-line, if the compiler supports
this flag. Some systems, like Windows, do not need this flag. Defaults to ON.
Enable all compiler warnings. Defaults to ON.
Enable pedantic mode. This disable compiler specific extensions, is
possible. Defaults to ON.
Stop and fail build, if a compiler warning is triggered. Defaults to OFF.
Build 32-bits executables and libraries on 64-bits systems. This option is
available only on some 64-bits unix systems. Defaults to OFF.
LLVM target to use for native code generation. This is required for JIT
generation. It defaults to "host", meaning that it shall pick the architecture
of the machine where LLVM is being built. If you are cross-compiling, set it
to the target architecture name.
Full path to a native TableGen executable (usually named ``tblgen``). This is
intended for cross-compiling: if the user sets this variable, no native
TableGen will be created.
Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
The path to GnuWin32 tools for tests. Valid on Windows host. Defaults to "",
then Lit seeks tools according to %PATH%. Lit can find tools(eg. grep, sort,
&c) on LLVM_LIT_TOOLS_DIR at first, without specifying GnuWin32 to %PATH%.
Indicates whether LLVM Interpreter will be linked with Foreign Function
Interface library. If the library or its headers are installed on a custom
location, you can set the variables FFI_INCLUDE_DIR and
Path to ``{Clang,lld,Polly}``\'s source directory. Defaults to
``tools/{clang,lld,polly}``. ``{Clang,lld,Polly}`` will not be built when it
is empty or it does not point valid path.
Enable building OProfile JIT support. Defaults to OFF
Enable building support for Intel JIT Events API. Defaults to OFF
Build with zlib to support compression/uncompression in LLVM tools.
Defaults to ON.
Executing the test suite
Testing is performed when the *check* target is built. For instance, if you are
using makefiles, execute this command while on the top level of your build
.. code-block:: console
$ make check
On Visual Studio, you may run tests to build the project "check".
Cross compiling
See `this wiki page <>`_ for
generic instructions on how to cross-compile with CMake. It goes into detailed
explanations and may seem daunting, but it is not. On the wiki page there are
several examples including toolchain files. Go directly to `this section
for a quick solution.
Also see the `LLVM-specific variables`_ section for variables used when
Embedding LLVM in your project
The most difficult part of adding LLVM to the build of a project is to determine
the set of LLVM libraries corresponding to the set of required LLVM
features. What follows is an example of how to obtain this information:
.. code-block:: cmake
# A convenience variable:
set(LLVM_ROOT "" CACHE PATH "Root of LLVM install.")
# A bit of a sanity check:
if( NOT EXISTS ${LLVM_ROOT}/include/llvm )
message(FATAL_ERROR "LLVM_ROOT (${LLVM_ROOT}) is not a valid LLVM install")
# We incorporate the CMake features provided by LLVM:
# Now set the header and library paths:
include_directories( ${LLVM_INCLUDE_DIRS} )
link_directories( ${LLVM_LIBRARY_DIRS} )
add_definitions( ${LLVM_DEFINITIONS} )
# Let's suppose we want to build a JIT compiler with support for
# binary code (no interpreter):
llvm_map_components_to_libraries(REQ_LLVM_LIBRARIES jit native)
# Finally, we link the LLVM libraries to our executable:
target_link_libraries(mycompiler ${REQ_LLVM_LIBRARIES})
This assumes that LLVM_ROOT points to an install of LLVM. The procedure works
too for uninstalled builds although we need to take care to add an
`include_directories` for the location of the headers on the LLVM source
directory (if we are building out-of-source.)
Alternativaly, you can utilize CMake's ``find_package`` functionality. Here is
an equivalent variant of snippet shown above:
.. code-block:: cmake
message(FATAL_ERROR "LLVM package can't be found. Set CMAKE_PREFIX_PATH variable to LLVM's installation prefix.")
include_directories( ${LLVM_INCLUDE_DIRS} )
link_directories( ${LLVM_LIBRARY_DIRS} )
llvm_map_components_to_libraries(REQ_LLVM_LIBRARIES jit native)
target_link_libraries(mycompiler ${REQ_LLVM_LIBRARIES})
.. _cmake-out-of-source-pass:
Developing LLVM pass out of source
It is possible to develop LLVM passes against installed LLVM. An example of
project layout provided below:
.. code-block:: none
<project dir>/
<pass name>/
Contents of ``<project dir>/CMakeLists.txt``:
.. code-block:: cmake
# Define add_llvm_* macro's.
add_subdirectory(<pass name>)
Contents of ``<project dir>/<pass name>/CMakeLists.txt``:
.. code-block:: cmake
When you are done developing your pass, you may wish to integrate it
into LLVM source tree. You can achieve it in two easy steps:
#. Copying ``<pass name>`` folder into ``<LLVM root>/lib/Transform`` directory.
#. Adding ``add_subdirectory(<pass name>)`` line into
``<LLVM root>/lib/Transform/CMakeLists.txt``.
Compiler/Platform specific topics
Notes for specific compilers and/or platforms.
Microsoft Visual C++
Specifies the maximum number of parallell compiler jobs to use per project
when building with msbuild or Visual Studio. Only supported for Visual Studio
2008 and Visual Studio 2010 CMake generators. 0 means use all
processors. Default is 0.