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_ABI_BREAKING_CHECKS**:STRING
274 Used to decide if LLVM should be built with ABI breaking checks or
275 not. Allowed values are `WITH_ASSERTS` (default), `FORCE_ON` and
276 `FORCE_OFF`. `WITH_ASSERTS` turns on ABI breaking checks in an
277 assertion enabled build. `FORCE_ON` (`FORCE_OFF`) turns them on
278 (off) irrespective of whether normal (`NDEBUG` based) assertions are
279 enabled or not. A version of LLVM built with ABI breaking checks
280 is not ABI compatible with a version built without it.
282 **LLVM_BUILD_32_BITS**:BOOL
283 Build 32-bits executables and libraries on 64-bits systems. This option is
284 available only on some 64-bits unix systems. Defaults to OFF.
286 **LLVM_TARGET_ARCH**:STRING
287 LLVM target to use for native code generation. This is required for JIT
288 generation. It defaults to "host", meaning that it shall pick the architecture
289 of the machine where LLVM is being built. If you are cross-compiling, set it
290 to the target architecture name.
292 **LLVM_TABLEGEN**:STRING
293 Full path to a native TableGen executable (usually named ``tblgen``). This is
294 intended for cross-compiling: if the user sets this variable, no native
295 TableGen will be created.
297 **LLVM_LIT_ARGS**:STRING
298 Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
299 By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
302 **LLVM_LIT_TOOLS_DIR**:PATH
303 The path to GnuWin32 tools for tests. Valid on Windows host. Defaults to "",
304 then Lit seeks tools according to %PATH%. Lit can find tools(eg. grep, sort,
305 &c) on LLVM_LIT_TOOLS_DIR at first, without specifying GnuWin32 to %PATH%.
307 **LLVM_ENABLE_FFI**:BOOL
308 Indicates whether LLVM Interpreter will be linked with Foreign Function
309 Interface library. If the library or its headers are installed on a custom
310 location, you can set the variables FFI_INCLUDE_DIR and
311 FFI_LIBRARY_DIR. Defaults to OFF.
313 **LLVM_EXTERNAL_{CLANG,LLD,POLLY}_SOURCE_DIR**:PATH
314 Path to ``{Clang,lld,Polly}``\'s source directory. Defaults to
315 ``tools/{clang,lld,polly}``. ``{Clang,lld,Polly}`` will not be built when it
316 is empty or it does not point to a valid path.
318 **LLVM_USE_OPROFILE**:BOOL
319 Enable building OProfile JIT support. Defaults to OFF
321 **LLVM_USE_INTEL_JITEVENTS**:BOOL
322 Enable building support for Intel JIT Events API. Defaults to OFF
324 **LLVM_ENABLE_ZLIB**:BOOL
325 Build with zlib to support compression/uncompression in LLVM tools.
328 **LLVM_USE_SANITIZER**:STRING
329 Define the sanitizer used to build LLVM binaries and tests. Possible values
330 are ``Address``, ``Memory``, ``MemoryWithOrigins`` and ``Undefined``.
331 Defaults to empty string.
333 **LLVM_PARALLEL_COMPILE_JOBS**:STRING
334 Define the maximum number of concurrent compilation jobs.
336 **LLVM_PARALLEL_LINK_JOBS**:STRING
337 Define the maximum number of concurrent link jobs.
339 **LLVM_BUILD_DOCS**:BOOL
340 Enables all enabled documentation targets (i.e. Doxgyen and Sphinx targets) to
341 be built as part of the normal build. If the ``install`` target is run then
342 this also enables all built documentation targets to be installed. Defaults to
345 **LLVM_ENABLE_DOXYGEN**:BOOL
346 Enables the generation of browsable HTML documentation using doxygen.
349 **LLVM_ENABLE_DOXYGEN_QT_HELP**:BOOL
350 Enables the generation of a Qt Compressed Help file. Defaults to OFF.
351 This affects the make target ``doxygen-llvm``. When enabled, apart from
352 the normal HTML output generated by doxygen, this will produce a QCH file
353 named ``org.llvm.qch``. You can then load this file into Qt Creator.
354 This option is only useful in combination with ``-DLLVM_ENABLE_DOXYGEN=ON``;
355 otherwise this has no effect.
357 **LLVM_DOXYGEN_QCH_FILENAME**:STRING
358 The filename of the Qt Compressed Help file that will be generated when
359 ``-DLLVM_ENABLE_DOXYGEN=ON`` and
360 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON`` are given. Defaults to
362 This option is only useful in combination with
363 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
364 otherwise this has no effect.
366 **LLVM_DOXYGEN_QHP_NAMESPACE**:STRING
367 Namespace under which the intermediate Qt Help Project file lives. See `Qt
369 for more information. Defaults to "org.llvm". This option is only useful in
370 combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise
373 **LLVM_DOXYGEN_QHP_CUST_FILTER_NAME**:STRING
374 See `Qt Help Project`_ for
375 more information. Defaults to the CMake variable ``${PACKAGE_STRING}`` which
376 is a combination of the package name and version string. This filter can then
377 be used in Qt Creator to select only documentation from LLVM when browsing
378 through all the help files that you might have loaded. This option is only
379 useful in combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
380 otherwise this has no effect.
382 .. _Qt Help Project: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-filters
384 **LLVM_DOXYGEN_QHELPGENERATOR_PATH**:STRING
385 The path to the ``qhelpgenerator`` executable. Defaults to whatever CMake's
386 ``find_program()`` can find. This option is only useful in combination with
387 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise this has no
390 **LLVM_ENABLE_SPHINX**:BOOL
391 If enabled CMake will search for the ``sphinx-build`` executable and will make
392 the ``SPHINX_OUTPUT_HTML`` and ``SPHINX_OUTPUT_MAN`` CMake options available.
395 **SPHINX_EXECUTABLE**:STRING
396 The path to the ``sphinx-build`` executable detected by CMake.
398 **SPHINX_OUTPUT_HTML**:BOOL
399 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) then the targets for
400 building the documentation as html are added (but not built by default unless
401 ``LLVM_BUILD_DOCS`` is enabled). There is a target for each project in the
402 source tree that uses sphinx (e.g. ``docs-llvm-html``, ``docs-clang-html``
403 and ``docs-lld-html``). Defaults to ON.
405 **SPHINX_OUTPUT_MAN**:BOOL
406 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) the targets for building
407 the man pages are added (but not built by default unless ``LLVM_BUILD_DOCS``
408 is enabled). Currently the only target added is ``docs-llvm-man``. Defaults
411 **SPHINX_WARNINGS_AS_ERRORS**:BOOL
412 If enabled then sphinx documentation warnings will be treated as
413 errors. Defaults to ON.
415 Executing the test suite
416 ========================
418 Testing is performed when the *check* target is built. For instance, if you are
419 using makefiles, execute this command while on the top level of your build
422 .. code-block:: console
426 On Visual Studio, you may run tests to build the project "check".
431 See `this wiki page <http://www.vtk.org/Wiki/CMake_Cross_Compiling>`_ for
432 generic instructions on how to cross-compile with CMake. It goes into detailed
433 explanations and may seem daunting, but it is not. On the wiki page there are
434 several examples including toolchain files. Go directly to `this section
435 <http://www.vtk.org/Wiki/CMake_Cross_Compiling#Information_how_to_set_up_various_cross_compiling_toolchains>`_
436 for a quick solution.
438 Also see the `LLVM-specific variables`_ section for variables used when
441 Embedding LLVM in your project
442 ==============================
444 From LLVM 3.5 onwards both the CMake and autoconf/Makefile build systems export
445 LLVM libraries as importable CMake targets. This means that clients of LLVM can
446 now reliably use CMake to develop their own LLVM based projects against an
447 installed version of LLVM regardless of how it was built.
449 Here is a simple example of CMakeLists.txt file that imports the LLVM libraries
450 and uses them to build a simple application ``simple-tool``.
452 .. code-block:: cmake
454 cmake_minimum_required(VERSION 2.8.8)
455 project(SimpleProject)
457 find_package(LLVM REQUIRED CONFIG)
459 message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
460 message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
462 # Set your project compile flags.
463 # E.g. if using the C++ header files
464 # you will need to enable C++11 support
467 include_directories(${LLVM_INCLUDE_DIRS})
468 add_definitions(${LLVM_DEFINITIONS})
470 # Now build our tools
471 add_executable(simple-tool tool.cpp)
473 # Find the libraries that correspond to the LLVM components
474 # that we wish to use
475 llvm_map_components_to_libnames(llvm_libs support core irreader)
477 # Link against LLVM libraries
478 target_link_libraries(simple-tool ${llvm_libs})
480 The ``find_package(...)`` directive when used in CONFIG mode (as in the above
481 example) will look for the ``LLVMConfig.cmake`` file in various locations (see
482 cmake manual for details). It creates a ``LLVM_DIR`` cache entry to save the
483 directory where ``LLVMConfig.cmake`` is found or allows the user to specify the
484 directory (e.g. by passing ``-DLLVM_DIR=/usr/share/llvm/cmake`` to
485 the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
487 This file is available in two different locations.
489 * ``<INSTALL_PREFIX>/share/llvm/cmake/LLVMConfig.cmake`` where
490 ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
491 On Linux typically this is ``/usr/share/llvm/cmake/LLVMConfig.cmake``.
493 * ``<LLVM_BUILD_ROOT>/share/llvm/cmake/LLVMConfig.cmake`` where
494 ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note this only
495 available when building LLVM with CMake**
497 If LLVM is installed in your operating system's normal installation prefix (e.g.
498 on Linux this is usually ``/usr/``) ``find_package(LLVM ...)`` will
499 automatically find LLVM if it is installed correctly. If LLVM is not installed
500 or you wish to build directly against the LLVM build tree you can use
501 ``LLVM_DIR`` as previously mentioned.
503 The ``LLVMConfig.cmake`` file sets various useful variables. Notable variables
507 The path to the LLVM CMake directory (i.e. the directory containing
511 A list of preprocessor defines that should be used when building against LLVM.
513 ``LLVM_ENABLE_ASSERTIONS``
514 This is set to ON if LLVM was built with assertions, otherwise OFF.
517 This is set to ON if LLVM was built with exception handling (EH) enabled,
521 This is set to ON if LLVM was built with run time type information (RTTI),
524 ``LLVM_INCLUDE_DIRS``
525 A list of include paths to directories containing LLVM header files.
527 ``LLVM_PACKAGE_VERSION``
528 The LLVM version. This string can be used with CMake conditionals. E.g. ``if
529 (${LLVM_PACKAGE_VERSION} VERSION_LESS "3.5")``.
531 ``LLVM_TOOLS_BINARY_DIR``
532 The path to the directory containing the LLVM tools (e.g. ``llvm-as``).
534 Notice that in the above example we link ``simple-tool`` against several LLVM
535 libraries. The list of libraries is determined by using the
536 ``llvm_map_components_to_libnames()`` CMake function. For a list of available
537 components look at the output of running ``llvm-config --components``.
539 Note that for LLVM < 3.5 ``llvm_map_components_to_libraries()`` was
540 used instead of ``llvm_map_components_to_libnames()``. This is now deprecated
541 and will be removed in a future version of LLVM.
543 .. _cmake-out-of-source-pass:
545 Developing LLVM passes out of source
546 ------------------------------------
548 It is possible to develop LLVM passes out of LLVM's source tree (i.e. against an
549 installed or built LLVM). An example of a project layout is provided below.
562 Contents of ``<project dir>/CMakeLists.txt``:
564 .. code-block:: cmake
566 find_package(LLVM REQUIRED CONFIG)
568 add_definitions(${LLVM_DEFINITIONS})
569 include_directories(${LLVM_INCLUDE_DIRS})
571 add_subdirectory(<pass name>)
573 Contents of ``<project dir>/<pass name>/CMakeLists.txt``:
575 .. code-block:: cmake
577 add_library(LLVMPassname MODULE Pass.cpp)
579 Note if you intend for this pass to be merged into the LLVM source tree at some
580 point in the future it might make more sense to use LLVM's internal
581 add_llvm_loadable_module function instead by...
584 Adding the following to ``<project dir>/CMakeLists.txt`` (after
585 ``find_package(LLVM ...)``)
587 .. code-block:: cmake
589 list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
592 And then changing ``<project dir>/<pass name>/CMakeLists.txt`` to
594 .. code-block:: cmake
596 add_llvm_loadable_module(LLVMPassname
600 When you are done developing your pass, you may wish to integrate it
601 into LLVM source tree. You can achieve it in two easy steps:
603 #. Copying ``<pass name>`` folder into ``<LLVM root>/lib/Transform`` directory.
605 #. Adding ``add_subdirectory(<pass name>)`` line into
606 ``<LLVM root>/lib/Transform/CMakeLists.txt``.
608 Compiler/Platform-specific topics
609 =================================
611 Notes for specific compilers and/or platforms.
616 **LLVM_COMPILER_JOBS**:STRING
617 Specifies the maximum number of parallell compiler jobs to use per project
618 when building with msbuild or Visual Studio. Only supported for the Visual
619 Studio 2010 CMake generator. 0 means use all processors. Default is 0.