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 a new contributor**, please start with the :doc:`GettingStarted`
16 page. This page is geared for existing contributors moving from the
17 legacy configure/make system.
19 If you are really anxious about getting a functional LLVM build, go to the
20 `Quick start`_ section. If you are a CMake novice, start with `Basic CMake usage`_
21 and then go back to the `Quick start`_ section once you know what you are doing. The
22 `Options and variables`_ section is a reference for customizing your build. If
23 you already have experience with CMake, this is the recommended starting point.
25 This page is geared towards users of the LLVM CMake build. If you're looking for
26 information about modifying the LLVM CMake build system you may want to see the
27 :doc:`CMakePrimer` page. It has a basic overview of the CMake language.
34 We use here the command-line, non-interactive CMake interface.
36 #. `Download <http://www.cmake.org/cmake/resources/software.html>`_ and install
37 CMake. Version 3.13.4 is the minimum required.
39 #. Open a shell. Your development tools must be reachable from this shell
40 through the PATH environment variable.
42 #. Create a build directory. Building LLVM in the source
43 directory is not supported. cd to this directory:
45 .. code-block:: console
50 #. Execute this command in the shell replacing `path/to/llvm/source/root` with
51 the path to the root of your LLVM source tree:
53 .. code-block:: console
55 $ cmake path/to/llvm/source/root
57 CMake will detect your development environment, perform a series of tests, and
58 generate the files required for building LLVM. CMake will use default values
59 for all build parameters. See the `Options and variables`_ section for
60 a list of build parameters that you can modify.
62 This can fail if CMake can't detect your toolset, or if it thinks that the
63 environment is not sane enough. In this case, make sure that the toolset that
64 you intend to use is the only one reachable from the shell, and that the shell
65 itself is the correct one for your development environment. CMake will refuse
66 to build MinGW makefiles if you have a POSIX shell reachable through the PATH
67 environment variable, for instance. You can force CMake to use a given build
68 tool; for instructions, see the `Usage`_ section, below. You may
69 also wish to control which targets LLVM enables, or which LLVM
70 components are built; see the `Frequently Used LLVM-related
73 #. After CMake has finished running, proceed to use IDE project files, or start
74 the build from the build directory:
76 .. code-block:: console
80 The ``--build`` option tells ``cmake`` to invoke the underlying build
81 tool (``make``, ``ninja``, ``xcodebuild``, ``msbuild``, etc.)
83 The underlying build tool can be invoked directly, of course, but
84 the ``--build`` option is portable.
86 #. After LLVM has finished building, install it from the build directory:
88 .. code-block:: console
90 $ cmake --build . --target install
92 The ``--target`` option with ``install`` parameter in addition to
93 the ``--build`` option tells ``cmake`` to build the ``install`` target.
95 It is possible to set a different install prefix at installation time
96 by invoking the ``cmake_install.cmake`` script generated in the
99 .. code-block:: console
101 $ cmake -DCMAKE_INSTALL_PREFIX=/tmp/llvm -P cmake_install.cmake
103 .. _Basic CMake usage:
109 This section explains basic aspects of CMake
110 which you may need in your day-to-day usage.
112 CMake comes with extensive documentation, in the form of html files, and as
113 online help accessible via the ``cmake`` executable itself. Execute ``cmake
114 --help`` for further help options.
116 CMake allows you to specify a build tool (e.g., GNU make, Visual Studio,
117 or Xcode). If not specified on the command line, CMake tries to guess which
118 build tool to use, based on your environment. Once it has identified your
119 build tool, CMake uses the corresponding *Generator* to create files for your
120 build tool (e.g., Makefiles or Visual Studio or Xcode project files). You can
121 explicitly specify the generator with the command line option ``-G "Name of the
122 generator"``. To see a list of the available generators on your system, execute
124 .. code-block:: console
128 This will list the generator names at the end of the help text.
130 Generators' names are case-sensitive, and may contain spaces. For this reason,
131 you should enter them exactly as they are listed in the ``cmake --help``
132 output, in quotes. For example, to generate project files specifically for
133 Visual Studio 12, you can execute:
135 .. code-block:: console
137 $ cmake -G "Visual Studio 12" path/to/llvm/source/root
139 For a given development platform there can be more than one adequate
140 generator. If you use Visual Studio, "NMake Makefiles" is a generator you can use
141 for building with NMake. By default, CMake chooses the most specific generator
142 supported by your development environment. If you want an alternative generator,
143 you must tell this to CMake with the ``-G`` option.
147 Explain variables and cache. Move explanation here from #options section.
149 .. _Options and variables:
151 Options and variables
152 =====================
154 Variables customize how the build will be generated. Options are boolean
155 variables, with possible values ON/OFF. Options and variables are defined on the
156 CMake command line like this:
158 .. code-block:: console
160 $ cmake -DVARIABLE=value path/to/llvm/source
162 You can set a variable after the initial CMake invocation to change its
163 value. You can also undefine a variable:
165 .. code-block:: console
167 $ cmake -UVARIABLE path/to/llvm/source
169 Variables are stored in the CMake cache. This is a file named ``CMakeCache.txt``
170 stored at the root of your build directory that is generated by ``cmake``.
171 Editing it yourself is not recommended.
173 Variables are listed in the CMake cache and later in this document with
174 the variable name and type separated by a colon. You can also specify the
175 variable and type on the CMake command line:
177 .. code-block:: console
179 $ cmake -DVARIABLE:TYPE=value path/to/llvm/source
181 Frequently-used CMake variables
182 -------------------------------
184 Here are some of the CMake variables that are used often, along with a
185 brief explanation. For full documentation, consult the CMake manual,
186 or execute ``cmake --help-variable VARIABLE_NAME``. See `Frequently
187 Used LLVM-related Variables`_ below for information about commonly
188 used variables that control features of LLVM and enabled subprojects.
190 **CMAKE_BUILD_TYPE**:STRING
191 Sets the build type for ``make``-based generators. Possible values are
192 Release, Debug, RelWithDebInfo and MinSizeRel. If you are using an IDE such as
193 Visual Studio, you should use the IDE settings to set the build type.
194 Be aware that Release and RelWithDebInfo use different optimization levels on
195 most platforms. Be aware that Release and
196 RelWithDebInfo use different optimization levels on most
197 platforms, and that the default value of ``LLVM_ENABLE_ASSERTIONS``
200 **CMAKE_INSTALL_PREFIX**:PATH
201 Path where LLVM will be installed when the "install" target is built.
203 **CMAKE_{C,CXX}_FLAGS**:STRING
204 Extra flags to use when compiling C and C++ source files respectively.
206 **CMAKE_{C,CXX}_COMPILER**:STRING
207 Specify the C and C++ compilers to use. If you have multiple
208 compilers installed, CMake might not default to the one you wish to
211 .. _Frequently Used LLVM-related variables:
213 Frequently Used LLVM-related variables
214 --------------------------------------
216 The default configuration may not match your requirements. Here are
217 LLVM variables that are frequently used to control that. The full
218 description is in `LLVM-related variables`_ below.
220 **LLVM_ENABLE_PROJECTS**:STRING
221 Control which projects are enabled. For example you may want to work on clang
222 or lldb by specifying ``-DLLVM_ENABLE_PROJECTS="clang;lldb"``.
224 **LLVM_LIBDIR_SUFFIX**:STRING
225 Extra suffix to append to the directory where libraries are to be
226 installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
227 to install libraries to ``/usr/lib64``.
229 **LLVM_PARALLEL_{COMPILE,LINK}_JOBS**:STRING
230 Building the llvm toolchain can use a lot of resources, particularly
231 linking. These options, when you use the Ninja generator, allow you
232 to restrict the parallelism. For example, to avoid OOMs or going
233 into swap, permit only one link job per 15GB of RAM available on a
234 32GB machine, specify ``-G Ninja -DLLVM_PARALLEL_LINK_JOBS=2``.
236 **LLVM_TARGETS_TO_BUILD**:STRING
237 Control which targets are enabled. For example you may only need to enable
238 your native target with, for example, ``-DLLVM_TARGETS_TO_BUILD=X86``.
240 **LLVM_USE_LINKER**:STRING
241 Override the system's default linker. For instance use ``lld`` with
242 ``-DLLVM_USE_LINKER=lld``.
244 Rarely-used CMake variables
245 ---------------------------
247 Here are some of the CMake variables that are rarely used, along with a brief
248 explanation and LLVM-related notes. For full documentation, consult the CMake
249 manual, or execute ``cmake --help-variable VARIABLE_NAME``.
251 **CMAKE_CXX_STANDARD**:STRING
252 Sets the C++ standard to conform to when building LLVM. Possible values are
253 14, 17, 20. LLVM Requires C++ 14 or higher. This defaults to 14.
255 .. _LLVM-related variables:
257 LLVM-related variables
258 -----------------------
260 These variables provide fine control over the build of LLVM and
261 enabled sub-projects. Nearly all of these variable names begin with
264 **BUILD_SHARED_LIBS**:BOOL
265 Flag indicating if each LLVM component (e.g. Support) is built as a shared
266 library (ON) or as a static library (OFF). Its default value is OFF. On
267 Windows, shared libraries may be used when building with MinGW, including
268 mingw-w64, but not when building with the Microsoft toolchain.
270 .. note:: BUILD_SHARED_LIBS is only recommended for use by LLVM developers.
271 If you want to build LLVM as a shared library, you should use the
272 ``LLVM_BUILD_LLVM_DYLIB`` option.
274 **LLVM_ABI_BREAKING_CHECKS**:STRING
275 Used to decide if LLVM should be built with ABI breaking checks or
276 not. Allowed values are `WITH_ASSERTS` (default), `FORCE_ON` and
277 `FORCE_OFF`. `WITH_ASSERTS` turns on ABI breaking checks in an
278 assertion enabled build. `FORCE_ON` (`FORCE_OFF`) turns them on
279 (off) irrespective of whether normal (`NDEBUG`-based) assertions are
280 enabled or not. A version of LLVM built with ABI breaking checks
281 is not ABI compatible with a version built without it.
283 **LLVM_APPEND_VC_REV**:BOOL
284 Embed version control revision info (Git revision id).
285 The version info is provided by the ``LLVM_REVISION`` macro in
286 ``llvm/include/llvm/Support/VCSRevision.h``. Developers using git who don't
287 need revision info can disable this option to avoid re-linking most binaries
288 after a branch switch. Defaults to ON.
290 **LLVM_BUILD_32_BITS**:BOOL
291 Build 32-bit executables and libraries on 64-bit systems. This option is
292 available only on some 64-bit Unix systems. Defaults to OFF.
294 **LLVM_BUILD_BENCHMARKS**:BOOL
295 Adds benchmarks to the list of default targets. Defaults to OFF.
297 **LLVM_BUILD_DOCS**:BOOL
298 Adds all *enabled* documentation targets (i.e. Doxgyen and Sphinx targets) as
299 dependencies of the default build targets. This results in all of the (enabled)
300 documentation targets being as part of a normal build. If the ``install``
301 target is run then this also enables all built documentation targets to be
302 installed. Defaults to OFF. To enable a particular documentation target, see
303 see LLVM_ENABLE_SPHINX and LLVM_ENABLE_DOXYGEN.
305 **LLVM_BUILD_EXAMPLES**:BOOL
306 Build LLVM examples. Defaults to OFF. Targets for building each example are
307 generated in any case. See documentation for *LLVM_BUILD_TOOLS* above for more
310 **LLVM_BUILD_INSTRUMENTED_COVERAGE**:BOOL
311 If enabled, `source-based code coverage
312 <https://clang.llvm.org/docs/SourceBasedCodeCoverage.html>`_ instrumentation
313 is enabled while building llvm. If CMake can locate the code coverage
314 scripts and the llvm-cov and llvm-profdata tools that pair to your compiler,
315 the build will also generate the `generate-coverage-report` target to generate
316 the code coverage report for LLVM, and the `clear-profile-data` utility target
317 to delete captured profile data. See documentation for
318 *LLVM_CODE_COVERAGE_TARGETS* and *LLVM_COVERAGE_SOURCE_DIRS* for more
319 information on configuring code coverage reports.
321 **LLVM_CODE_COVERAGE_TARGETS**:STRING
322 If set to a semicolon separated list of targets, those targets will be used
323 to drive the code coverage reports. If unset, the target list will be
324 constructed using the LLVM build's CMake export list.
326 **LLVM_COVERAGE_SOURCE_DIRS**:STRING
327 If set to a semicolon separated list of directories, the coverage reports
328 will limit code coverage summaries to just the listed directories. If unset,
329 coverage reports will include all sources identified by the tooling.
331 **LLVM_BUILD_LLVM_DYLIB**:BOOL
332 If enabled, the target for building the libLLVM shared library is added.
333 This library contains all of LLVM's components in a single shared library.
334 Defaults to OFF. This cannot be used in conjunction with BUILD_SHARED_LIBS.
335 Tools will only be linked to the libLLVM shared library if LLVM_LINK_LLVM_DYLIB
337 The components in the library can be customised by setting LLVM_DYLIB_COMPONENTS
338 to a list of the desired components.
339 This option is not available on Windows.
341 **LLVM_BUILD_TESTS**:BOOL
342 Include LLVM unit tests in the 'all' build target. Defaults to OFF. Targets
343 for building each unit test are generated in any case. You can build a
344 specific unit test using the targets defined under *unittests*, such as
345 ADTTests, IRTests, SupportTests, etc. (Search for ``add_llvm_unittest`` in
346 the subdirectories of *unittests* for a complete list of unit tests.) It is
347 possible to build all unit tests with the target *UnitTests*.
349 **LLVM_BUILD_TOOLS**:BOOL
350 Build LLVM tools. Defaults to ON. Targets for building each tool are generated
351 in any case. You can build a tool separately by invoking its target. For
352 example, you can build *llvm-as* with a Makefile-based system by executing *make
353 llvm-as* at the root of your build directory.
355 **LLVM_CCACHE_BUILD**:BOOL
356 If enabled and the ``ccache`` program is available, then LLVM will be
357 built using ``ccache`` to speed up rebuilds of LLVM and its components.
358 Defaults to OFF. The size and location of the cache maintained
359 by ``ccache`` can be adjusted via the LLVM_CCACHE_MAXSIZE and LLVM_CCACHE_DIR
360 options, which are passed to the CCACHE_MAXSIZE and CCACHE_DIR environment
361 variables, respectively.
363 **LLVM_CREATE_XCODE_TOOLCHAIN**:BOOL
364 macOS Only: If enabled CMake will generate a target named
365 'install-xcode-toolchain'. This target will create a directory at
366 $CMAKE_INSTALL_PREFIX/Toolchains containing an xctoolchain directory which can
367 be used to override the default system tools.
369 **LLVM_DOXYGEN_QCH_FILENAME**:STRING
370 The filename of the Qt Compressed Help file that will be generated when
371 ``-DLLVM_ENABLE_DOXYGEN=ON`` and
372 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON`` are given. Defaults to
374 This option is only useful in combination with
375 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
376 otherwise it has no effect.
378 **LLVM_DOXYGEN_QHELPGENERATOR_PATH**:STRING
379 The path to the ``qhelpgenerator`` executable. Defaults to whatever CMake's
380 ``find_program()`` can find. This option is only useful in combination with
381 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise it has no
384 **LLVM_DOXYGEN_QHP_CUST_FILTER_NAME**:STRING
385 See `Qt Help Project`_ for
386 more information. Defaults to the CMake variable ``${PACKAGE_STRING}`` which
387 is a combination of the package name and version string. This filter can then
388 be used in Qt Creator to select only documentation from LLVM when browsing
389 through all the help files that you might have loaded. This option is only
390 useful in combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
391 otherwise it has no effect.
393 .. _Qt Help Project: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-filters
395 **LLVM_DOXYGEN_QHP_NAMESPACE**:STRING
396 Namespace under which the intermediate Qt Help Project file lives. See `Qt
398 for more information. Defaults to "org.llvm". This option is only useful in
399 combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise
402 **LLVM_DOXYGEN_SVG**:BOOL
403 Uses .svg files instead of .png files for graphs in the Doxygen output.
406 **LLVM_ENABLE_ASSERTIONS**:BOOL
407 Enables code assertions. Defaults to ON if and only if ``CMAKE_BUILD_TYPE``
410 **LLVM_ENABLE_BINDINGS**:BOOL
411 If disabled, do not try to build the OCaml and go bindings.
413 **LLVM_ENABLE_DIA_SDK**:BOOL
414 Enable building with MSVC DIA SDK for PDB debugging support. Available
415 only with MSVC. Defaults to ON.
417 **LLVM_ENABLE_DOXYGEN**:BOOL
418 Enables the generation of browsable HTML documentation using doxygen.
421 **LLVM_ENABLE_DOXYGEN_QT_HELP**:BOOL
422 Enables the generation of a Qt Compressed Help file. Defaults to OFF.
423 This affects the make target ``doxygen-llvm``. When enabled, apart from
424 the normal HTML output generated by doxygen, this will produce a QCH file
425 named ``org.llvm.qch``. You can then load this file into Qt Creator.
426 This option is only useful in combination with ``-DLLVM_ENABLE_DOXYGEN=ON``;
427 otherwise this has no effect.
429 **LLVM_ENABLE_EH**:BOOL
430 Build LLVM with exception-handling support. This is necessary if you wish to
431 link against LLVM libraries and make use of C++ exceptions in your own code
432 that need to propagate through LLVM code. Defaults to OFF.
434 **LLVM_ENABLE_EXPENSIVE_CHECKS**:BOOL
435 Enable additional time/memory expensive checking. Defaults to OFF.
437 **LLVM_ENABLE_FFI**:BOOL
438 Indicates whether the LLVM Interpreter will be linked with the Foreign Function
439 Interface library (libffi) in order to enable calling external functions.
440 If the library or its headers are installed in a custom
441 location, you can also set the variables FFI_INCLUDE_DIR and
442 FFI_LIBRARY_DIR to the directories where ffi.h and libffi.so can be found,
443 respectively. Defaults to OFF.
445 **LLVM_ENABLE_IDE**:BOOL
446 Tell the build system that an IDE is being used. This in turn disables the
447 creation of certain convenience build system targets, such as the various
448 ``install-*`` and ``check-*`` targets, since IDEs don't always deal well with
449 a large number of targets. This is usually autodetected, but it can be
450 configured manually to explicitly control the generation of those targets. One
451 scenario where a manual override may be desirable is when using Visual Studio
452 2017's CMake integration, which would not be detected as an IDE otherwise.
454 **LLVM_ENABLE_LIBCXX**:BOOL
455 If the host compiler and linker supports the stdlib flag, -stdlib=libc++ is
456 passed to invocations of both so that the project is built using libc++
457 instead of stdlibc++. Defaults to OFF.
459 **LLVM_ENABLE_LIBPFM**:BOOL
460 Enable building with libpfm to support hardware counter measurements in LLVM
464 **LLVM_ENABLE_LLD**:BOOL
465 This option is equivalent to `-DLLVM_USE_LINKER=lld`, except during a 2-stage
466 build where a dependency is added from the first stage to the second ensuring
467 that lld is built before stage2 begins.
469 **LLVM_ENABLE_LTO**:STRING
470 Add ``-flto`` or ``-flto=`` flags to the compile and link command
471 lines, enabling link-time optimization. Possible values are ``Off``,
472 ``On``, ``Thin`` and ``Full``. Defaults to OFF.
474 **LLVM_ENABLE_MODULES**:BOOL
475 Compile with `Clang Header Modules
476 <https://clang.llvm.org/docs/Modules.html>`_.
478 **LLVM_ENABLE_PEDANTIC**:BOOL
479 Enable pedantic mode. This disables compiler-specific extensions, if
480 possible. Defaults to ON.
482 **LLVM_ENABLE_PIC**:BOOL
483 Add the ``-fPIC`` flag to the compiler command-line, if the compiler supports
484 this flag. Some systems, like Windows, do not need this flag. Defaults to ON.
486 **LLVM_ENABLE_PROJECTS**:STRING
487 Semicolon-separated list of projects to build, or *all* for building all
488 (clang, lldb, compiler-rt, lld, polly, etc) projects. This flag assumes
489 that projects are checked out side-by-side and not nested, i.e. clang
490 needs to be in parallel of llvm instead of nested in `llvm/tools`.
491 This feature allows to have one build for only LLVM and another for clang+llvm
492 using the same source checkout.
494 ``clang;clang-tools-extra;compiler-rt;cross-project-tests;libc;libclc;lld;lldb;openmp;polly;pstl``
496 **LLVM_ENABLE_RUNTIMES**:STRING
497 Build libc++, libc++abi or other projects using that a just-built compiler.
498 This is the correct way to build libc++ when putting together a toolchain.
499 It will build the builtins separately from the other runtimes to preserve
500 correct dependency ordering. If you want to build the runtimes using a system
501 compiler, see the `libc++ documentation <https://libcxx.llvm.org/BuildingLibcxx.html>`_.
502 Note: the list should not have duplicates with `LLVM_ENABLE_PROJECTS`.
504 ``compiler-rt;libc;libcxx;libcxxabi;libunwind;openmp``
505 To enable all of them, use:
506 ``LLVM_ENABLE_RUNTIMES=all``
509 **LLVM_ENABLE_RTTI**:BOOL
510 Build LLVM with run-time type information. Defaults to OFF.
512 **LLVM_ENABLE_SPHINX**:BOOL
513 If specified, CMake will search for the ``sphinx-build`` executable and will make
514 the ``SPHINX_OUTPUT_HTML`` and ``SPHINX_OUTPUT_MAN`` CMake options available.
517 **LLVM_ENABLE_THREADS**:BOOL
518 Build with threads support, if available. Defaults to ON.
520 **LLVM_ENABLE_UNWIND_TABLES**:BOOL
521 Enable unwind tables in the binary. Disabling unwind tables can reduce the
522 size of the libraries. Defaults to ON.
524 **LLVM_ENABLE_WARNINGS**:BOOL
525 Enable all compiler warnings. Defaults to ON.
527 **LLVM_ENABLE_WERROR**:BOOL
528 Stop and fail the build, if a compiler warning is triggered. Defaults to OFF.
530 **LLVM_ENABLE_Z3_SOLVER**:BOOL
531 If enabled, the Z3 constraint solver is activated for the Clang static analyzer.
532 A recent version of the z3 library needs to be available on the system.
534 **LLVM_ENABLE_ZLIB**:BOOL
535 Enable building with zlib to support compression/uncompression in LLVM tools.
538 **LLVM_EXPERIMENTAL_TARGETS_TO_BUILD**:STRING
539 Semicolon-separated list of experimental targets to build and linked into
540 llvm. This will build the experimental target without needing it to add to the
541 list of all the targets available in the LLVM's main CMakeLists.txt.
543 **LLVM_EXTERNAL_{CLANG,LLD,POLLY}_SOURCE_DIR**:PATH
544 These variables specify the path to the source directory for the external
545 LLVM projects Clang, lld, and Polly, respectively, relative to the top-level
546 source directory. If the in-tree subdirectory for an external project
547 exists (e.g., llvm/tools/clang for Clang), then the corresponding variable
548 will not be used. If the variable for an external project does not point
549 to a valid path, then that project will not be built.
551 **LLVM_EXTERNAL_PROJECTS**:STRING
552 Semicolon-separated list of additional external projects to build as part of
553 llvm. For each project LLVM_EXTERNAL_<NAME>_SOURCE_DIR have to be specified
554 with the path for the source code of the project. Example:
555 ``-DLLVM_EXTERNAL_PROJECTS="Foo;Bar"
556 -DLLVM_EXTERNAL_FOO_SOURCE_DIR=/src/foo
557 -DLLVM_EXTERNAL_BAR_SOURCE_DIR=/src/bar``.
559 **LLVM_EXTERNALIZE_DEBUGINFO**:BOOL
560 Generate dSYM files and strip executables and libraries (Darwin Only).
563 **LLVM_FORCE_USE_OLD_TOOLCHAIN**:BOOL
564 If enabled, the compiler and standard library versions won't be checked. LLVM
565 may not compile at all, or might fail at runtime due to known bugs in these
568 **LLVM_INCLUDE_BENCHMARKS**:BOOL
569 Generate build targets for the LLVM benchmarks. Defaults to ON.
571 **LLVM_INCLUDE_EXAMPLES**:BOOL
572 Generate build targets for the LLVM examples. Defaults to ON. You can use this
573 option to disable the generation of build targets for the LLVM examples.
575 **LLVM_INCLUDE_TESTS**:BOOL
576 Generate build targets for the LLVM unit tests. Defaults to ON. You can use
577 this option to disable the generation of build targets for the LLVM unit
580 **LLVM_INCLUDE_TOOLS**:BOOL
581 Generate build targets for the LLVM tools. Defaults to ON. You can use this
582 option to disable the generation of build targets for the LLVM tools.
584 **LLVM_INSTALL_BINUTILS_SYMLINKS**:BOOL
585 Install symlinks from the binutils tool names to the corresponding LLVM tools.
586 For example, ar will be symlinked to llvm-ar.
588 **LLVM_INSTALL_CCTOOLS_SYMLINKS**:BOOL
589 Install symliks from the cctools tool names to the corresponding LLVM tools.
590 For example, lipo will be symlinked to llvm-lipo.
592 **LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
593 The path to install OCamldoc-generated HTML documentation to. This path can
594 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
595 `share/doc/llvm/ocaml-html`.
597 **LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
598 The path to install Sphinx-generated HTML documentation to. This path can
599 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
600 `share/doc/llvm/html`.
602 **LLVM_INSTALL_UTILS**:BOOL
603 If enabled, utility binaries like ``FileCheck`` and ``not`` will be installed
604 to CMAKE_INSTALL_PREFIX.
606 **LLVM_INTEGRATED_CRT_ALLOC**:PATH
607 On Windows, allows embedding a different C runtime allocator into the LLVM
608 tools and libraries. Using a lock-free allocator such as the ones listed below
609 greatly decreases ThinLTO link time by about an order of magnitude. It also
610 midly improves Clang build times, by about 5-10%. At the moment, rpmalloc,
611 snmalloc and mimalloc are supported. Use the path to `git clone` to select
612 the respective allocator, for example:
614 .. code-block:: console
616 $ D:\git> git clone https://github.com/mjansson/rpmalloc
617 $ D:\llvm-project> cmake ... -DLLVM_INTEGRATED_CRT_ALLOC=D:\git\rpmalloc
619 This flag needs to be used along with the static CRT, ie. if building the
620 Release target, add -DLLVM_USE_CRT_RELEASE=MT.
622 **LLVM_INSTALL_DOXYGEN_HTML_DIR**:STRING
623 The path to install Doxygen-generated HTML documentation to. This path can
624 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
625 `share/doc/llvm/doxygen-html`.
627 **LLVM_LINK_LLVM_DYLIB**:BOOL
628 If enabled, tools will be linked with the libLLVM shared library. Defaults
629 to OFF. Setting LLVM_LINK_LLVM_DYLIB to ON also sets LLVM_BUILD_LLVM_DYLIB
631 This option is not available on Windows.
633 **LLVM_LIT_ARGS**:STRING
634 Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
635 By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
638 **LLVM_LIT_TOOLS_DIR**:PATH
639 The path to GnuWin32 tools for tests. Valid on Windows host. Defaults to
640 the empty string, in which case lit will look for tools needed for tests
641 (e.g. ``grep``, ``sort``, etc.) in your %PATH%. If GnuWin32 is not in your
642 %PATH%, then you can set this variable to the GnuWin32 directory so that
643 lit can find tools needed for tests in that directory.
645 **LLVM_OPTIMIZED_TABLEGEN**:BOOL
646 If enabled and building a debug or asserts build the CMake build system will
647 generate a Release build tree to build a fully optimized tablegen for use
648 during the build. Enabling this option can significantly speed up build times
649 especially when building LLVM in Debug configurations.
651 **LLVM_PARALLEL_COMPILE_JOBS**:STRING
652 Define the maximum number of concurrent compilation jobs.
654 **LLVM_PARALLEL_LINK_JOBS**:STRING
655 Define the maximum number of concurrent link jobs.
657 **LLVM_PROFDATA_FILE**:PATH
658 Path to a profdata file to pass into clang's -fprofile-instr-use flag. This
659 can only be specified if you're building with clang.
661 **LLVM_REVERSE_ITERATION**:BOOL
662 If enabled, all supported unordered llvm containers would be iterated in
663 reverse order. This is useful for uncovering non-determinism caused by
664 iteration of unordered containers.
666 **LLVM_STATIC_LINK_CXX_STDLIB**:BOOL
667 Statically link to the C++ standard library if possible. This uses the flag
668 "-static-libstdc++", but a Clang host compiler will statically link to libc++
669 if used in conjunction with the **LLVM_ENABLE_LIBCXX** flag. Defaults to OFF.
671 **LLVM_TABLEGEN**:STRING
672 Full path to a native TableGen executable (usually named ``llvm-tblgen``). This is
673 intended for cross-compiling: if the user sets this variable, no native
674 TableGen will be created.
676 **LLVM_TARGET_ARCH**:STRING
677 LLVM target to use for native code generation. This is required for JIT
678 generation. It defaults to "host", meaning that it shall pick the architecture
679 of the machine where LLVM is being built. If you are cross-compiling, set it
680 to the target architecture name.
682 **LLVM_TARGETS_TO_BUILD**:STRING
683 Semicolon-separated list of targets to build, or *all* for building all
684 targets. Case-sensitive. Defaults to *all*. Example:
685 ``-DLLVM_TARGETS_TO_BUILD="X86;PowerPC"``.
687 **LLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN**:BOOL
688 If enabled, the compiler version check will only warn when using a toolchain
689 which is about to be deprecated, instead of emitting an error.
691 **LLVM_UBSAN_FLAGS**:STRING
692 Defines the set of compile flags used to enable UBSan. Only used if
693 ``LLVM_USE_SANITIZER`` contains ``Undefined``. This can be used to override
694 the default set of UBSan flags.
696 **LLVM_USE_CRT_{target}**:STRING
697 On Windows, tells which version of the C runtime library (CRT) should be used.
698 For example, -DLLVM_USE_CRT_RELEASE=MT would statically link the CRT into the
699 LLVM tools and library.
701 **LLVM_USE_INTEL_JITEVENTS**:BOOL
702 Enable building support for Intel JIT Events API. Defaults to OFF.
704 **LLVM_USE_LINKER**:STRING
705 Add ``-fuse-ld={name}`` to the link invocation. The possible value depend on
706 your compiler, for clang the value can be an absolute path to your custom
707 linker, otherwise clang will prefix the name with ``ld.`` and apply its usual
708 search. For example to link LLVM with the Gold linker, cmake can be invoked
709 with ``-DLLVM_USE_LINKER=gold``.
711 **LLVM_USE_NEWPM**:BOOL
712 If enabled, use the experimental new pass manager.
714 **LLVM_USE_OPROFILE**:BOOL
715 Enable building OProfile JIT support. Defaults to OFF.
717 **LLVM_USE_PERF**:BOOL
718 Enable building support for Perf (linux profiling tool) JIT support. Defaults to OFF.
720 **LLVM_USE_RELATIVE_PATHS_IN_FILES**:BOOL
721 Rewrite absolute source paths in sources and debug info to relative ones. The
722 source prefix can be adjusted via the LLVM_SOURCE_PREFIX variable.
724 **LLVM_USE_RELATIVE_PATHS_IN_DEBUG_INFO**:BOOL
725 Rewrite absolute source paths in debug info to relative ones. The source prefix
726 can be adjusted via the LLVM_SOURCE_PREFIX variable.
728 **LLVM_USE_SANITIZER**:STRING
729 Define the sanitizer used to build LLVM binaries and tests. Possible values
730 are ``Address``, ``Memory``, ``MemoryWithOrigins``, ``Undefined``, ``Thread``,
731 ``DataFlow``, and ``Address;Undefined``. Defaults to empty string.
733 **LLVM_USE_SPLIT_DWARF**:BOOL
734 If enabled CMake will pass ``-gsplit-dwarf`` to the compiler. This option
735 reduces link-time memory usage by reducing the amount of debug information that
736 the linker needs to resolve. It is recommended for platforms using the ELF object
737 format, like Linux systems when linker memory usage is too high.
739 **SPHINX_EXECUTABLE**:STRING
740 The path to the ``sphinx-build`` executable detected by CMake.
741 For installation instructions, see
742 https://www.sphinx-doc.org/en/master/usage/installation.html
744 **SPHINX_OUTPUT_HTML**:BOOL
745 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) then the targets for
746 building the documentation as html are added (but not built by default unless
747 ``LLVM_BUILD_DOCS`` is enabled). There is a target for each project in the
748 source tree that uses sphinx (e.g. ``docs-llvm-html``, ``docs-clang-html``
749 and ``docs-lld-html``). Defaults to ON.
751 **SPHINX_OUTPUT_MAN**:BOOL
752 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) the targets for building
753 the man pages are added (but not built by default unless ``LLVM_BUILD_DOCS``
754 is enabled). Currently the only target added is ``docs-llvm-man``. Defaults
757 **SPHINX_WARNINGS_AS_ERRORS**:BOOL
758 If enabled then sphinx documentation warnings will be treated as
759 errors. Defaults to ON.
764 Recently LLVM and Clang have been adding some more complicated build system
765 features. Utilizing these new features often involves a complicated chain of
766 CMake variables passed on the command line. Clang provides a collection of CMake
767 cache scripts to make these features more approachable.
769 CMake cache files are utilized using CMake's -C flag:
771 .. code-block:: console
773 $ cmake -C <path to cache file> <path to sources>
775 CMake cache scripts are processed in an isolated scope, only cached variables
776 remain set when the main configuration runs. CMake cached variables do not reset
777 variables that are already set unless the FORCE option is specified.
779 A few notes about CMake Caches:
781 - Order of command line arguments is important
783 - -D arguments specified before -C are set before the cache is processed and
784 can be read inside the cache file
785 - -D arguments specified after -C are set after the cache is processed and
786 are unset inside the cache file
788 - All -D arguments will override cache file settings
789 - CMAKE_TOOLCHAIN_FILE is evaluated after both the cache file and the command
791 - It is recommended that all -D options should be specified *before* -C
793 For more information about some of the advanced build configurations supported
794 via Cache files see :doc:`AdvancedBuilds`.
799 Testing is performed when the *check-all* target is built. For instance, if you are
800 using Makefiles, execute this command in the root of your build directory:
802 .. code-block:: console
806 On Visual Studio, you may run tests by building the project "check-all".
807 For more information about testing, see the :doc:`TestingGuide`.
812 See `this wiki page <https://gitlab.kitware.com/cmake/community/wikis/doc/cmake/CrossCompiling>`_ for
813 generic instructions on how to cross-compile with CMake. It goes into detailed
814 explanations and may seem daunting, but it is not. On the wiki page there are
815 several examples including toolchain files. Go directly to the
816 ``Information how to set up various cross compiling toolchains`` section
817 for a quick solution.
819 Also see the `LLVM-related variables`_ section for variables used when
822 Embedding LLVM in your project
823 ==============================
825 From LLVM 3.5 onwards the CMake build system exports LLVM libraries as
826 importable CMake targets. This means that clients of LLVM can now reliably use
827 CMake to develop their own LLVM-based projects against an installed version of
828 LLVM regardless of how it was built.
830 Here is a simple example of a CMakeLists.txt file that imports the LLVM libraries
831 and uses them to build a simple application ``simple-tool``.
833 .. code-block:: cmake
835 cmake_minimum_required(VERSION 3.13.4)
836 project(SimpleProject)
838 find_package(LLVM REQUIRED CONFIG)
840 message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
841 message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
843 # Set your project compile flags.
844 # E.g. if using the C++ header files
845 # you will need to enable C++11 support
848 include_directories(${LLVM_INCLUDE_DIRS})
849 separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
850 add_definitions(${LLVM_DEFINITIONS_LIST})
852 # Now build our tools
853 add_executable(simple-tool tool.cpp)
855 # Find the libraries that correspond to the LLVM components
856 # that we wish to use
857 llvm_map_components_to_libnames(llvm_libs support core irreader)
859 # Link against LLVM libraries
860 target_link_libraries(simple-tool ${llvm_libs})
862 The ``find_package(...)`` directive when used in CONFIG mode (as in the above
863 example) will look for the ``LLVMConfig.cmake`` file in various locations (see
864 cmake manual for details). It creates a ``LLVM_DIR`` cache entry to save the
865 directory where ``LLVMConfig.cmake`` is found or allows the user to specify the
866 directory (e.g. by passing ``-DLLVM_DIR=/usr/lib/cmake/llvm`` to
867 the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
869 This file is available in two different locations.
871 * ``<INSTALL_PREFIX>/lib/cmake/llvm/LLVMConfig.cmake`` where
872 ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
873 On Linux typically this is ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
875 * ``<LLVM_BUILD_ROOT>/lib/cmake/llvm/LLVMConfig.cmake`` where
876 ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note: this is only
877 available when building LLVM with CMake.**
879 If LLVM is installed in your operating system's normal installation prefix (e.g.
880 on Linux this is usually ``/usr/``) ``find_package(LLVM ...)`` will
881 automatically find LLVM if it is installed correctly. If LLVM is not installed
882 or you wish to build directly against the LLVM build tree you can use
883 ``LLVM_DIR`` as previously mentioned.
885 The ``LLVMConfig.cmake`` file sets various useful variables. Notable variables
889 The path to the LLVM CMake directory (i.e. the directory containing
893 A list of preprocessor defines that should be used when building against LLVM.
895 ``LLVM_ENABLE_ASSERTIONS``
896 This is set to ON if LLVM was built with assertions, otherwise OFF.
899 This is set to ON if LLVM was built with exception handling (EH) enabled,
903 This is set to ON if LLVM was built with run time type information (RTTI),
906 ``LLVM_INCLUDE_DIRS``
907 A list of include paths to directories containing LLVM header files.
909 ``LLVM_PACKAGE_VERSION``
910 The LLVM version. This string can be used with CMake conditionals, e.g., ``if
911 (${LLVM_PACKAGE_VERSION} VERSION_LESS "3.5")``.
913 ``LLVM_TOOLS_BINARY_DIR``
914 The path to the directory containing the LLVM tools (e.g. ``llvm-as``).
916 Notice that in the above example we link ``simple-tool`` against several LLVM
917 libraries. The list of libraries is determined by using the
918 ``llvm_map_components_to_libnames()`` CMake function. For a list of available
919 components look at the output of running ``llvm-config --components``.
921 Note that for LLVM < 3.5 ``llvm_map_components_to_libraries()`` was
922 used instead of ``llvm_map_components_to_libnames()``. This is now deprecated
923 and will be removed in a future version of LLVM.
925 .. _cmake-out-of-source-pass:
927 Developing LLVM passes out of source
928 ------------------------------------
930 It is possible to develop LLVM passes out of LLVM's source tree (i.e. against an
931 installed or built LLVM). An example of a project layout is provided below.
944 Contents of ``<project dir>/CMakeLists.txt``:
946 .. code-block:: cmake
948 find_package(LLVM REQUIRED CONFIG)
950 separate_arguments(LLVM_DEFINITIONS_LIST NATIVE_COMMAND ${LLVM_DEFINITIONS})
951 add_definitions(${LLVM_DEFINITIONS_LIST})
952 include_directories(${LLVM_INCLUDE_DIRS})
954 add_subdirectory(<pass name>)
956 Contents of ``<project dir>/<pass name>/CMakeLists.txt``:
958 .. code-block:: cmake
960 add_library(LLVMPassname MODULE Pass.cpp)
962 Note if you intend for this pass to be merged into the LLVM source tree at some
963 point in the future it might make more sense to use LLVM's internal
964 ``add_llvm_library`` function with the MODULE argument instead by...
967 Adding the following to ``<project dir>/CMakeLists.txt`` (after
968 ``find_package(LLVM ...)``)
970 .. code-block:: cmake
972 list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
975 And then changing ``<project dir>/<pass name>/CMakeLists.txt`` to
977 .. code-block:: cmake
979 add_llvm_library(LLVMPassname MODULE
983 When you are done developing your pass, you may wish to integrate it
984 into the LLVM source tree. You can achieve it in two easy steps:
986 #. Copying ``<pass name>`` folder into ``<LLVM root>/lib/Transform`` directory.
988 #. Adding ``add_subdirectory(<pass name>)`` line into
989 ``<LLVM root>/lib/Transform/CMakeLists.txt``.
991 Compiler/Platform-specific topics
992 =================================
994 Notes for specific compilers and/or platforms.
999 **LLVM_COMPILER_JOBS**:STRING
1000 Specifies the maximum number of parallel compiler jobs to use per project
1001 when building with msbuild or Visual Studio. Only supported for the Visual
1002 Studio 2010 CMake generator. 0 means use all processors. Default is 0.