1 ========================
2 Building LLVM with CMake
3 ========================
11 `CMake <http://www.cmake.org/>`_ is a cross-platform build-generator tool. CMake
12 does not build the project, it generates the files needed by your build tool
13 (GNU make, Visual Studio, etc) for building LLVM.
15 If you are really anxious about getting a functional LLVM build, go to the
16 `Quick start`_ section. If you are a CMake novice, start on `Basic CMake usage`_
17 and then go back to the `Quick start`_ once you know what you are doing. The
18 `Options and variables`_ section is a reference for customizing your build. If
19 you already have experience with CMake, this is the recommended starting point.
26 We use here the command-line, non-interactive CMake interface.
28 #. `Download <http://www.cmake.org/cmake/resources/software.html>`_ and install
29 CMake. Version 2.8.8 is the minimum required.
31 #. Open a shell. Your development tools must be reachable from this shell
32 through the PATH environment variable.
34 #. Create a directory for containing the build. It is not supported to build
35 LLVM on the source directory. cd to this directory:
37 .. code-block:: console
42 #. Execute this command on the shell replacing `path/to/llvm/source/root` with
43 the path to the root of your LLVM source tree:
45 .. code-block:: console
47 $ cmake path/to/llvm/source/root
49 CMake will detect your development environment, perform a series of test and
50 generate the files required for building LLVM. CMake will use default values
51 for all build parameters. See the `Options and variables`_ section for
52 fine-tuning your build
54 This can fail if CMake can't detect your toolset, or if it thinks that the
55 environment is not sane enough. On this case make sure that the toolset that
56 you intend to use is the only one reachable from the shell and that the shell
57 itself is the correct one for you development environment. CMake will refuse
58 to build MinGW makefiles if you have a POSIX shell reachable through the PATH
59 environment variable, for instance. You can force CMake to use a given build
60 tool, see the `Usage`_ section.
62 #. After CMake has finished running, proceed to use IDE project files or start
63 the build from the build directory:
65 .. code-block:: console
69 The ``--build`` option tells ``cmake`` to invoke the underlying build
70 tool (``make``, ``ninja``, ``xcodebuild``, ``msbuild``, etc).
72 The underlying build tool can be invoked directly either of course, but
73 the ``--build`` option is portable.
75 #. After LLVM has finished building, install it from the build directory:
77 .. code-block:: console
79 $ cmake --build . --target install
81 The ``--target`` option with ``install`` parameter in addition to
82 the ``--build`` option tells ``cmake`` to build the ``install`` target.
84 It is possible to set a different install prefix at installation time
85 by invoking the ``cmake_install.cmake`` script generated in the
88 .. code-block:: console
90 $ cmake -DCMAKE_INSTALL_PREFIX=/tmp/llvm -P cmake_install.cmake
92 .. _Basic CMake usage:
98 This section explains basic aspects of CMake, mostly for explaining those
99 options which you may need on your day-to-day usage.
101 CMake comes with extensive documentation in the form of html files and on the
102 cmake executable itself. Execute ``cmake --help`` for further help options.
104 CMake requires to know for which build tool it shall generate files (GNU make,
105 Visual Studio, Xcode, etc). If not specified on the command line, it tries to
106 guess it based on you environment. Once identified the build tool, CMake uses
107 the corresponding *Generator* for creating files for your build tool. You can
108 explicitly specify the generator with the command line option ``-G "Name of the
109 generator"``. For knowing the available generators on your platform, execute
111 .. code-block:: console
115 This will list the generator's names at the end of the help text. Generator's
116 names are case-sensitive. Example:
118 .. code-block:: console
120 $ cmake -G "Visual Studio 11" path/to/llvm/source/root
122 For a given development platform there can be more than one adequate
123 generator. If you use Visual Studio "NMake Makefiles" is a generator you can use
124 for building with NMake. By default, CMake chooses the more specific generator
125 supported by your development environment. If you want an alternative generator,
126 you must tell this to CMake with the ``-G`` option.
130 Explain variables and cache. Move explanation here from #options section.
132 .. _Options and variables:
134 Options and variables
135 =====================
137 Variables customize how the build will be generated. Options are boolean
138 variables, with possible values ON/OFF. Options and variables are defined on the
139 CMake command line like this:
141 .. code-block:: console
143 $ cmake -DVARIABLE=value path/to/llvm/source
145 You can set a variable after the initial CMake invocation for changing its
146 value. You can also undefine a variable:
148 .. code-block:: console
150 $ cmake -UVARIABLE path/to/llvm/source
152 Variables are stored on the CMake cache. This is a file named ``CMakeCache.txt``
153 on the root of the build directory. Do not hand-edit it.
155 Variables are listed here appending its type after a colon. It is correct to
156 write the variable and the type on the CMake command line:
158 .. code-block:: console
160 $ cmake -DVARIABLE:TYPE=value path/to/llvm/source
162 Frequently-used CMake variables
163 -------------------------------
165 Here are some of the CMake variables that are used often, along with a
166 brief explanation and LLVM-specific notes. For full documentation, check the
167 CMake docs or execute ``cmake --help-variable VARIABLE_NAME``.
169 **CMAKE_BUILD_TYPE**:STRING
170 Sets the build type for ``make`` based generators. Possible values are
171 Release, Debug, RelWithDebInfo and MinSizeRel. On systems like Visual Studio
172 the user sets the build type with the IDE settings.
174 **CMAKE_INSTALL_PREFIX**:PATH
175 Path where LLVM will be installed if "make install" is invoked or the
176 "INSTALL" target is built.
178 **LLVM_LIBDIR_SUFFIX**:STRING
179 Extra suffix to append to the directory where libraries are to be
180 installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
181 to install libraries to ``/usr/lib64``.
183 **CMAKE_C_FLAGS**:STRING
184 Extra flags to use when compiling C source files.
186 **CMAKE_CXX_FLAGS**:STRING
187 Extra flags to use when compiling C++ source files.
189 **BUILD_SHARED_LIBS**:BOOL
190 Flag indicating if shared libraries will be built. Its default value is
191 OFF. Shared libraries are not supported on Windows and not recommended on the
194 .. _LLVM-specific variables:
196 LLVM-specific variables
197 -----------------------
199 **LLVM_TARGETS_TO_BUILD**:STRING
200 Semicolon-separated list of targets to build, or *all* for building all
201 targets. Case-sensitive. Defaults to *all*. Example:
202 ``-DLLVM_TARGETS_TO_BUILD="X86;PowerPC"``.
204 **LLVM_BUILD_TOOLS**:BOOL
205 Build LLVM tools. Defaults to ON. Targets for building each tool are generated
206 in any case. You can build an tool separately by invoking its target. For
207 example, you can build *llvm-as* with a makefile-based system executing *make
208 llvm-as* on the root of your build directory.
210 **LLVM_INCLUDE_TOOLS**:BOOL
211 Generate build targets for the LLVM tools. Defaults to ON. You can use that
212 option for disabling the generation of build targets for the LLVM tools.
214 **LLVM_BUILD_EXAMPLES**:BOOL
215 Build LLVM examples. Defaults to OFF. Targets for building each example are
216 generated in any case. See documentation for *LLVM_BUILD_TOOLS* above for more
219 **LLVM_INCLUDE_EXAMPLES**:BOOL
220 Generate build targets for the LLVM examples. Defaults to ON. You can use that
221 option for disabling the generation of build targets for the LLVM examples.
223 **LLVM_BUILD_TESTS**:BOOL
224 Build LLVM unit tests. Defaults to OFF. Targets for building each unit test
225 are generated in any case. You can build a specific unit test with the target
226 *UnitTestNameTests* (where at this time *UnitTestName* can be ADT, Analysis,
227 ExecutionEngine, JIT, Support, Transform, VMCore; see the subdirectories of
228 *unittests* for an updated list.) It is possible to build all unit tests with
229 the target *UnitTests*.
231 **LLVM_INCLUDE_TESTS**:BOOL
232 Generate build targets for the LLVM unit tests. Defaults to ON. You can use
233 that option for disabling the generation of build targets for the LLVM unit
236 **LLVM_APPEND_VC_REV**:BOOL
237 Append version control revision info (svn revision number or Git revision id)
238 to LLVM version string (stored in the PACKAGE_VERSION macro). For this to work
239 cmake must be invoked before the build. Defaults to OFF.
241 **LLVM_ENABLE_THREADS**:BOOL
242 Build with threads support, if available. Defaults to ON.
244 **LLVM_ENABLE_CXX1Y**:BOOL
245 Build in C++1y mode, if available. Defaults to OFF.
247 **LLVM_ENABLE_ASSERTIONS**:BOOL
248 Enables code assertions. Defaults to ON if and only if ``CMAKE_BUILD_TYPE``
251 **LLVM_ENABLE_EH**:BOOL
252 Build LLVM with exception handling support. This is necessary if you wish to
253 link against LLVM libraries and make use of C++ exceptions in your own code
254 that need to propagate through LLVM code. Defaults to OFF.
256 **LLVM_ENABLE_PIC**:BOOL
257 Add the ``-fPIC`` flag for the compiler command-line, if the compiler supports
258 this flag. Some systems, like Windows, do not need this flag. Defaults to ON.
260 **LLVM_ENABLE_RTTI**:BOOL
261 Build LLVM with run time type information. Defaults to OFF.
263 **LLVM_ENABLE_WARNINGS**:BOOL
264 Enable all compiler warnings. Defaults to ON.
266 **LLVM_ENABLE_PEDANTIC**:BOOL
267 Enable pedantic mode. This disables compiler specific extensions, if
268 possible. Defaults to ON.
270 **LLVM_ENABLE_WERROR**:BOOL
271 Stop and fail build, if a compiler warning is triggered. Defaults to OFF.
273 **LLVM_BUILD_32_BITS**:BOOL
274 Build 32-bits executables and libraries on 64-bits systems. This option is
275 available only on some 64-bits unix systems. Defaults to OFF.
277 **LLVM_TARGET_ARCH**:STRING
278 LLVM target to use for native code generation. This is required for JIT
279 generation. It defaults to "host", meaning that it shall pick the architecture
280 of the machine where LLVM is being built. If you are cross-compiling, set it
281 to the target architecture name.
283 **LLVM_TABLEGEN**:STRING
284 Full path to a native TableGen executable (usually named ``tblgen``). This is
285 intended for cross-compiling: if the user sets this variable, no native
286 TableGen will be created.
288 **LLVM_LIT_ARGS**:STRING
289 Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
290 By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
293 **LLVM_LIT_TOOLS_DIR**:PATH
294 The path to GnuWin32 tools for tests. Valid on Windows host. Defaults to "",
295 then Lit seeks tools according to %PATH%. Lit can find tools(eg. grep, sort,
296 &c) on LLVM_LIT_TOOLS_DIR at first, without specifying GnuWin32 to %PATH%.
298 **LLVM_ENABLE_FFI**:BOOL
299 Indicates whether LLVM Interpreter will be linked with Foreign Function
300 Interface library. If the library or its headers are installed on a custom
301 location, you can set the variables FFI_INCLUDE_DIR and
302 FFI_LIBRARY_DIR. Defaults to OFF.
304 **LLVM_EXTERNAL_{CLANG,LLD,POLLY}_SOURCE_DIR**:PATH
305 Path to ``{Clang,lld,Polly}``\'s source directory. Defaults to
306 ``tools/{clang,lld,polly}``. ``{Clang,lld,Polly}`` will not be built when it
307 is empty or it does not point to a valid path.
309 **LLVM_USE_OPROFILE**:BOOL
310 Enable building OProfile JIT support. Defaults to OFF
312 **LLVM_USE_INTEL_JITEVENTS**:BOOL
313 Enable building support for Intel JIT Events API. Defaults to OFF
315 **LLVM_ENABLE_ZLIB**:BOOL
316 Build with zlib to support compression/uncompression in LLVM tools.
319 **LLVM_USE_SANITIZER**:STRING
320 Define the sanitizer used to build LLVM binaries and tests. Possible values
321 are ``Address``, ``Memory``, ``MemoryWithOrigins`` and ``Undefined``.
322 Defaults to empty string.
324 **LLVM_PARALLEL_COMPILE_JOBS**:STRING
325 Define the maximum number of concurrent compilation jobs.
327 **LLVM_PARALLEL_LINK_JOBS**:STRING
328 Define the maximum number of concurrent link jobs.
330 **LLVM_BUILD_DOCS**:BOOL
331 Enables all enabled documentation targets (i.e. Doxgyen and Sphinx targets) to
332 be built as part of the normal build. If the ``install`` target is run then
333 this also enables all built documentation targets to be installed. Defaults to
336 **LLVM_ENABLE_DOXYGEN**:BOOL
337 Enables the generation of browsable HTML documentation using doxygen.
340 **LLVM_ENABLE_DOXYGEN_QT_HELP**:BOOL
341 Enables the generation of a Qt Compressed Help file. Defaults to OFF.
342 This affects the make target ``doxygen-llvm``. When enabled, apart from
343 the normal HTML output generated by doxygen, this will produce a QCH file
344 named ``org.llvm.qch``. You can then load this file into Qt Creator.
345 This option is only useful in combination with ``-DLLVM_ENABLE_DOXYGEN=ON``;
346 otherwise this has no effect.
348 **LLVM_DOXYGEN_QCH_FILENAME**:STRING
349 The filename of the Qt Compressed Help file that will be generated when
350 ``-DLLVM_ENABLE_DOXYGEN=ON`` and
351 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON`` are given. Defaults to
353 This option is only useful in combination with
354 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
355 otherwise this has no effect.
357 **LLVM_DOXYGEN_QHP_NAMESPACE**:STRING
358 Namespace under which the intermediate Qt Help Project file lives. See `Qt
360 for more information. Defaults to "org.llvm". This option is only useful in
361 combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise
364 **LLVM_DOXYGEN_QHP_CUST_FILTER_NAME**:STRING
365 See `Qt Help Project`_ for
366 more information. Defaults to the CMake variable ``${PACKAGE_STRING}`` which
367 is a combination of the package name and version string. This filter can then
368 be used in Qt Creator to select only documentation from LLVM when browsing
369 through all the help files that you might have loaded. This option is only
370 useful in combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
371 otherwise this has no effect.
373 .. _Qt Help Project: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-filters
375 **LLVM_DOXYGEN_QHELPGENERATOR_PATH**:STRING
376 The path to the ``qhelpgenerator`` executable. Defaults to whatever CMake's
377 ``find_program()`` can find. This option is only useful in combination with
378 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise this has no
381 **LLVM_ENABLE_SPHINX**:BOOL
382 If enabled CMake will search for the ``sphinx-build`` executable and will make
383 the ``SPHINX_OUTPUT_HTML`` and ``SPHINX_OUTPUT_MAN`` CMake options available.
386 **SPHINX_EXECUTABLE**:STRING
387 The path to the ``sphinx-build`` executable detected by CMake.
389 **SPHINX_OUTPUT_HTML**:BOOL
390 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) then the targets for
391 building the documentation as html are added (but not built by default unless
392 ``LLVM_BUILD_DOCS`` is enabled). There is a target for each project in the
393 source tree that uses sphinx (e.g. ``docs-llvm-html``, ``docs-clang-html``
394 and ``docs-lld-html``). Defaults to ON.
396 **SPHINX_OUTPUT_MAN**:BOOL
397 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) the targets for building
398 the man pages are added (but not built by default unless ``LLVM_BUILD_DOCS``
399 is enabled). Currently the only target added is ``docs-llvm-man``. Defaults
402 **SPHINX_WARNINGS_AS_ERRORS**:BOOL
403 If enabled then sphinx documentation warnings will be treated as
404 errors. Defaults to ON.
406 Executing the test suite
407 ========================
409 Testing is performed when the *check* target is built. For instance, if you are
410 using makefiles, execute this command while on the top level of your build
413 .. code-block:: console
417 On Visual Studio, you may run tests to build the project "check".
422 See `this wiki page <http://www.vtk.org/Wiki/CMake_Cross_Compiling>`_ for
423 generic instructions on how to cross-compile with CMake. It goes into detailed
424 explanations and may seem daunting, but it is not. On the wiki page there are
425 several examples including toolchain files. Go directly to `this section
426 <http://www.vtk.org/Wiki/CMake_Cross_Compiling#Information_how_to_set_up_various_cross_compiling_toolchains>`_
427 for a quick solution.
429 Also see the `LLVM-specific variables`_ section for variables used when
432 Embedding LLVM in your project
433 ==============================
435 From LLVM 3.5 onwards both the CMake and autoconf/Makefile build systems export
436 LLVM libraries as importable CMake targets. This means that clients of LLVM can
437 now reliably use CMake to develop their own LLVM based projects against an
438 installed version of LLVM regardless of how it was built.
440 Here is a simple example of CMakeLists.txt file that imports the LLVM libraries
441 and uses them to build a simple application ``simple-tool``.
443 .. code-block:: cmake
445 cmake_minimum_required(VERSION 2.8.8)
446 project(SimpleProject)
448 find_package(LLVM REQUIRED CONFIG)
450 message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
451 message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
453 # Set your project compile flags.
454 # E.g. if using the C++ header files
455 # you will need to enable C++11 support
458 include_directories(${LLVM_INCLUDE_DIRS})
459 add_definitions(${LLVM_DEFINITIONS})
461 # Now build our tools
462 add_executable(simple-tool tool.cpp)
464 # Find the libraries that correspond to the LLVM components
465 # that we wish to use
466 llvm_map_components_to_libnames(llvm_libs support core irreader)
468 # Link against LLVM libraries
469 target_link_libraries(simple-tool ${llvm_libs})
471 The ``find_package(...)`` directive when used in CONFIG mode (as in the above
472 example) will look for the ``LLVMConfig.cmake`` file in various locations (see
473 cmake manual for details). It creates a ``LLVM_DIR`` cache entry to save the
474 directory where ``LLVMConfig.cmake`` is found or allows the user to specify the
475 directory (e.g. by passing ``-DLLVM_DIR=/usr/share/llvm/cmake`` to
476 the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
478 This file is available in two different locations.
480 * ``<INSTALL_PREFIX>/share/llvm/cmake/LLVMConfig.cmake`` where
481 ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
482 On Linux typically this is ``/usr/share/llvm/cmake/LLVMConfig.cmake``.
484 * ``<LLVM_BUILD_ROOT>/share/llvm/cmake/LLVMConfig.cmake`` where
485 ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note this only
486 available when building LLVM with CMake**
488 If LLVM is installed in your operating system's normal installation prefix (e.g.
489 on Linux this is usually ``/usr/``) ``find_package(LLVM ...)`` will
490 automatically find LLVM if it is installed correctly. If LLVM is not installed
491 or you wish to build directly against the LLVM build tree you can use
492 ``LLVM_DIR`` as previously mentioned.
494 The ``LLVMConfig.cmake`` file sets various useful variables. Notable variables
498 The path to the LLVM CMake directory (i.e. the directory containing
502 A list of preprocessor defines that should be used when building against LLVM.
504 ``LLVM_ENABLE_ASSERTIONS``
505 This is set to ON if LLVM was built with assertions, otherwise OFF.
508 This is set to ON if LLVM was built with exception handling (EH) enabled,
512 This is set to ON if LLVM was built with run time type information (RTTI),
515 ``LLVM_INCLUDE_DIRS``
516 A list of include paths to directories containing LLVM header files.
518 ``LLVM_PACKAGE_VERSION``
519 The LLVM version. This string can be used with CMake conditionals. E.g. ``if
520 (${LLVM_PACKAGE_VERSION} VERSION_LESS "3.5")``.
522 ``LLVM_TOOLS_BINARY_DIR``
523 The path to the directory containing the LLVM tools (e.g. ``llvm-as``).
525 Notice that in the above example we link ``simple-tool`` against several LLVM
526 libraries. The list of libraries is determined by using the
527 ``llvm_map_components_to_libnames()`` CMake function. For a list of available
528 components look at the output of running ``llvm-config --components``.
530 Note that for LLVM < 3.5 ``llvm_map_components_to_libraries()`` was
531 used instead of ``llvm_map_components_to_libnames()``. This is now deprecated
532 and will be removed in a future version of LLVM.
534 .. _cmake-out-of-source-pass:
536 Developing LLVM passes out of source
537 ------------------------------------
539 It is possible to develop LLVM passes out of LLVM's source tree (i.e. against an
540 installed or built LLVM). An example of a project layout is provided below.
553 Contents of ``<project dir>/CMakeLists.txt``:
555 .. code-block:: cmake
557 find_package(LLVM REQUIRED CONFIG)
559 add_definitions(${LLVM_DEFINITIONS})
560 include_directories(${LLVM_INCLUDE_DIRS})
562 add_subdirectory(<pass name>)
564 Contents of ``<project dir>/<pass name>/CMakeLists.txt``:
566 .. code-block:: cmake
568 add_library(LLVMPassname MODULE Pass.cpp)
570 Note if you intend for this pass to be merged into the LLVM source tree at some
571 point in the future it might make more sense to use LLVM's internal
572 add_llvm_loadable_module function instead by...
575 Adding the following to ``<project dir>/CMakeLists.txt`` (after
576 ``find_package(LLVM ...)``)
578 .. code-block:: cmake
580 list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
583 And then changing ``<project dir>/<pass name>/CMakeLists.txt`` to
585 .. code-block:: cmake
587 add_llvm_loadable_module(LLVMPassname
591 When you are done developing your pass, you may wish to integrate it
592 into LLVM source tree. You can achieve it in two easy steps:
594 #. Copying ``<pass name>`` folder into ``<LLVM root>/lib/Transform`` directory.
596 #. Adding ``add_subdirectory(<pass name>)`` line into
597 ``<LLVM root>/lib/Transform/CMakeLists.txt``.
599 Compiler/Platform-specific topics
600 =================================
602 Notes for specific compilers and/or platforms.
607 **LLVM_COMPILER_JOBS**:STRING
608 Specifies the maximum number of parallell compiler jobs to use per project
609 when building with msbuild or Visual Studio. Only supported for the Visual
610 Studio 2010 CMake generator. 0 means use all processors. Default is 0.