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 3.4.3 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.
70 #. After CMake has finished running, proceed to use IDE project files, or start
71 the build from the build directory:
73 .. code-block:: console
77 The ``--build`` option tells ``cmake`` to invoke the underlying build
78 tool (``make``, ``ninja``, ``xcodebuild``, ``msbuild``, etc.)
80 The underlying build tool can be invoked directly, of course, but
81 the ``--build`` option is portable.
83 #. After LLVM has finished building, install it from the build directory:
85 .. code-block:: console
87 $ cmake --build . --target install
89 The ``--target`` option with ``install`` parameter in addition to
90 the ``--build`` option tells ``cmake`` to build the ``install`` target.
92 It is possible to set a different install prefix at installation time
93 by invoking the ``cmake_install.cmake`` script generated in the
96 .. code-block:: console
98 $ cmake -DCMAKE_INSTALL_PREFIX=/tmp/llvm -P cmake_install.cmake
100 .. _Basic CMake usage:
106 This section explains basic aspects of CMake
107 which you may need in your day-to-day usage.
109 CMake comes with extensive documentation, in the form of html files, and as
110 online help accessible via the ``cmake`` executable itself. Execute ``cmake
111 --help`` for further help options.
113 CMake allows you to specify a build tool (e.g., GNU make, Visual Studio,
114 or Xcode). If not specified on the command line, CMake tries to guess which
115 build tool to use, based on your environment. Once it has identified your
116 build tool, CMake uses the corresponding *Generator* to create files for your
117 build tool (e.g., Makefiles or Visual Studio or Xcode project files). You can
118 explicitly specify the generator with the command line option ``-G "Name of the
119 generator"``. To see a list of the available generators on your system, execute
121 .. code-block:: console
125 This will list the generator names at the end of the help text.
127 Generators' names are case-sensitive, and may contain spaces. For this reason,
128 you should enter them exactly as they are listed in the ``cmake --help``
129 output, in quotes. For example, to generate project files specifically for
130 Visual Studio 12, you can execute:
132 .. code-block:: console
134 $ cmake -G "Visual Studio 12" path/to/llvm/source/root
136 For a given development platform there can be more than one adequate
137 generator. If you use Visual Studio, "NMake Makefiles" is a generator you can use
138 for building with NMake. By default, CMake chooses the most specific generator
139 supported by your development environment. If you want an alternative generator,
140 you must tell this to CMake with the ``-G`` option.
144 Explain variables and cache. Move explanation here from #options section.
146 .. _Options and variables:
148 Options and variables
149 =====================
151 Variables customize how the build will be generated. Options are boolean
152 variables, with possible values ON/OFF. Options and variables are defined on the
153 CMake command line like this:
155 .. code-block:: console
157 $ cmake -DVARIABLE=value path/to/llvm/source
159 You can set a variable after the initial CMake invocation to change its
160 value. You can also undefine a variable:
162 .. code-block:: console
164 $ cmake -UVARIABLE path/to/llvm/source
166 Variables are stored in the CMake cache. This is a file named ``CMakeCache.txt``
167 stored at the root of your build directory that is generated by ``cmake``.
168 Editing it yourself is not recommended.
170 Variables are listed in the CMake cache and later in this document with
171 the variable name and type separated by a colon. You can also specify the
172 variable and type on the CMake command line:
174 .. code-block:: console
176 $ cmake -DVARIABLE:TYPE=value path/to/llvm/source
178 Frequently-used CMake variables
179 -------------------------------
181 Here are some of the CMake variables that are used often, along with a
182 brief explanation and LLVM-specific notes. For full documentation, consult the
183 CMake manual, or execute ``cmake --help-variable VARIABLE_NAME``.
185 **CMAKE_BUILD_TYPE**:STRING
186 Sets the build type for ``make``-based generators. Possible values are
187 Release, Debug, RelWithDebInfo and MinSizeRel. If you are using an IDE such as
188 Visual Studio, you should use the IDE settings to set the build type.
189 Be aware that Release and RelWithDebInfo use different optimization levels on
192 **CMAKE_INSTALL_PREFIX**:PATH
193 Path where LLVM will be installed if "make install" is invoked or the
194 "install" target is built.
196 **LLVM_LIBDIR_SUFFIX**:STRING
197 Extra suffix to append to the directory where libraries are to be
198 installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
199 to install libraries to ``/usr/lib64``.
201 **CMAKE_C_FLAGS**:STRING
202 Extra flags to use when compiling C source files.
204 **CMAKE_CXX_FLAGS**:STRING
205 Extra flags to use when compiling C++ source files.
207 .. _LLVM-specific variables:
209 LLVM-specific variables
210 -----------------------
212 **LLVM_TARGETS_TO_BUILD**:STRING
213 Semicolon-separated list of targets to build, or *all* for building all
214 targets. Case-sensitive. Defaults to *all*. Example:
215 ``-DLLVM_TARGETS_TO_BUILD="X86;PowerPC"``.
217 **LLVM_BUILD_TOOLS**:BOOL
218 Build LLVM tools. Defaults to ON. Targets for building each tool are generated
219 in any case. You can build a tool separately by invoking its target. For
220 example, you can build *llvm-as* with a Makefile-based system by executing *make
221 llvm-as* at the root of your build directory.
223 **LLVM_INCLUDE_TOOLS**:BOOL
224 Generate build targets for the LLVM tools. Defaults to ON. You can use this
225 option to disable the generation of build targets for the LLVM tools.
227 **LLVM_INSTALL_BINUTILS_SYMLINKS**:BOOL
228 Install symlinks from the binutils tool names to the corresponding LLVM tools.
229 For example, ar will be symlinked to llvm-ar.
231 **LLVM_INSTALL_CCTOOLS_SYMLINKS**:BOOL
232 Install symliks from the cctools tool names to the corresponding LLVM tools.
233 For example, dsymutil will be symlinked to llvm-dsymutil.
235 **LLVM_BUILD_EXAMPLES**:BOOL
236 Build LLVM examples. Defaults to OFF. Targets for building each example are
237 generated in any case. See documentation for *LLVM_BUILD_TOOLS* above for more
240 **LLVM_INCLUDE_EXAMPLES**:BOOL
241 Generate build targets for the LLVM examples. Defaults to ON. You can use this
242 option to disable the generation of build targets for the LLVM examples.
244 **LLVM_BUILD_TESTS**:BOOL
245 Build LLVM unit tests. Defaults to OFF. Targets for building each unit test
246 are generated in any case. You can build a specific unit test using the
247 targets defined under *unittests*, such as ADTTests, IRTests, SupportTests,
248 etc. (Search for ``add_llvm_unittest`` in the subdirectories of *unittests*
249 for a complete list of unit tests.) It is possible to build all unit tests
250 with the target *UnitTests*.
252 **LLVM_INCLUDE_TESTS**:BOOL
253 Generate build targets for the LLVM unit tests. Defaults to ON. You can use
254 this option to disable the generation of build targets for the LLVM unit
257 **LLVM_APPEND_VC_REV**:BOOL
258 Embed version control revision info (svn revision number or Git revision id).
259 The version info is provided by the ``LLVM_REVISION`` macro in
260 ``llvm/include/llvm/Support/VCSRevision.h``. Developers using git who don't
261 need revision info can disable this option to avoid re-linking most binaries
262 after a branch switch. Defaults to ON.
264 **LLVM_ENABLE_THREADS**:BOOL
265 Build with threads support, if available. Defaults to ON.
267 **LLVM_ENABLE_CXX1Y**:BOOL
268 Build in C++1y mode, if available. Defaults to OFF.
270 **LLVM_ENABLE_ASSERTIONS**:BOOL
271 Enables code assertions. Defaults to ON if and only if ``CMAKE_BUILD_TYPE``
274 **LLVM_ENABLE_EH**:BOOL
275 Build LLVM with exception-handling support. This is necessary if you wish to
276 link against LLVM libraries and make use of C++ exceptions in your own code
277 that need to propagate through LLVM code. Defaults to OFF.
279 **LLVM_ENABLE_EXPENSIVE_CHECKS**:BOOL
280 Enable additional time/memory expensive checking. Defaults to OFF.
282 **LLVM_ENABLE_PIC**:BOOL
283 Add the ``-fPIC`` flag to the compiler command-line, if the compiler supports
284 this flag. Some systems, like Windows, do not need this flag. Defaults to ON.
286 **LLVM_ENABLE_RTTI**:BOOL
287 Build LLVM with run-time type information. Defaults to OFF.
289 **LLVM_ENABLE_WARNINGS**:BOOL
290 Enable all compiler warnings. Defaults to ON.
292 **LLVM_ENABLE_PEDANTIC**:BOOL
293 Enable pedantic mode. This disables compiler-specific extensions, if
294 possible. Defaults to ON.
296 **LLVM_ENABLE_WERROR**:BOOL
297 Stop and fail the build, if a compiler warning is triggered. Defaults to OFF.
299 **LLVM_ABI_BREAKING_CHECKS**:STRING
300 Used to decide if LLVM should be built with ABI breaking checks or
301 not. Allowed values are `WITH_ASSERTS` (default), `FORCE_ON` and
302 `FORCE_OFF`. `WITH_ASSERTS` turns on ABI breaking checks in an
303 assertion enabled build. `FORCE_ON` (`FORCE_OFF`) turns them on
304 (off) irrespective of whether normal (`NDEBUG`-based) assertions are
305 enabled or not. A version of LLVM built with ABI breaking checks
306 is not ABI compatible with a version built without it.
308 **LLVM_BUILD_32_BITS**:BOOL
309 Build 32-bit executables and libraries on 64-bit systems. This option is
310 available only on some 64-bit Unix systems. Defaults to OFF.
312 **LLVM_TARGET_ARCH**:STRING
313 LLVM target to use for native code generation. This is required for JIT
314 generation. It defaults to "host", meaning that it shall pick the architecture
315 of the machine where LLVM is being built. If you are cross-compiling, set it
316 to the target architecture name.
318 **LLVM_TABLEGEN**:STRING
319 Full path to a native TableGen executable (usually named ``llvm-tblgen``). This is
320 intended for cross-compiling: if the user sets this variable, no native
321 TableGen will be created.
323 **LLVM_LIT_ARGS**:STRING
324 Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
325 By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
328 **LLVM_LIT_TOOLS_DIR**:PATH
329 The path to GnuWin32 tools for tests. Valid on Windows host. Defaults to
330 the empty string, in which case lit will look for tools needed for tests
331 (e.g. ``grep``, ``sort``, etc.) in your %PATH%. If GnuWin32 is not in your
332 %PATH%, then you can set this variable to the GnuWin32 directory so that
333 lit can find tools needed for tests in that directory.
335 **LLVM_ENABLE_FFI**:BOOL
336 Indicates whether the LLVM Interpreter will be linked with the Foreign Function
337 Interface library (libffi) in order to enable calling external functions.
338 If the library or its headers are installed in a custom
339 location, you can also set the variables FFI_INCLUDE_DIR and
340 FFI_LIBRARY_DIR to the directories where ffi.h and libffi.so can be found,
341 respectively. Defaults to OFF.
343 **LLVM_EXTERNAL_{CLANG,LLD,POLLY}_SOURCE_DIR**:PATH
344 These variables specify the path to the source directory for the external
345 LLVM projects Clang, lld, and Polly, respectively, relative to the top-level
346 source directory. If the in-tree subdirectory for an external project
347 exists (e.g., llvm/tools/clang for Clang), then the corresponding variable
348 will not be used. If the variable for an external project does not point
349 to a valid path, then that project will not be built.
351 **LLVM_ENABLE_PROJECTS**:STRING
352 Semicolon-separated list of projects to build, or *all* for building all
353 (clang, libcxx, libcxxabi, lldb, compiler-rt, lld, polly) projects.
354 This flag assumes that projects are checked out side-by-side and not nested,
355 i.e. clang needs to be in parallel of llvm instead of nested in `llvm/tools`.
356 This feature allows to have one build for only LLVM and another for clang+llvm
357 using the same source checkout.
359 **LLVM_EXTERNAL_PROJECTS**:STRING
360 Semicolon-separated list of additional external projects to build as part of
361 llvm. For each project LLVM_EXTERNAL_<NAME>_SOURCE_DIR have to be specified
362 with the path for the source code of the project. Example:
363 ``-DLLVM_EXTERNAL_PROJECTS="Foo;Bar"
364 -DLLVM_EXTERNAL_FOO_SOURCE_DIR=/src/foo
365 -DLLVM_EXTERNAL_BAR_SOURCE_DIR=/src/bar``.
367 **LLVM_USE_OPROFILE**:BOOL
368 Enable building OProfile JIT support. Defaults to OFF.
370 **LLVM_PROFDATA_FILE**:PATH
371 Path to a profdata file to pass into clang's -fprofile-instr-use flag. This
372 can only be specified if you're building with clang.
374 **LLVM_USE_INTEL_JITEVENTS**:BOOL
375 Enable building support for Intel JIT Events API. Defaults to OFF.
377 **LLVM_ENABLE_ZLIB**:BOOL
378 Enable building with zlib to support compression/uncompression in LLVM tools.
381 **LLVM_ENABLE_DIA_SDK**:BOOL
382 Enable building with MSVC DIA SDK for PDB debugging support. Available
383 only with MSVC. Defaults to ON.
385 **LLVM_USE_SANITIZER**:STRING
386 Define the sanitizer used to build LLVM binaries and tests. Possible values
387 are ``Address``, ``Memory``, ``MemoryWithOrigins``, ``Undefined``, ``Thread``,
388 and ``Address;Undefined``. Defaults to empty string.
390 **LLVM_ENABLE_LTO**:STRING
391 Add ``-flto`` or ``-flto=`` flags to the compile and link command
392 lines, enabling link-time optimization. Possible values are ``Off``,
393 ``On``, ``Thin`` and ``Full``. Defaults to OFF.
395 **LLVM_USE_LINKER**:STRING
396 Add ``-fuse-ld={name}`` to the link invocation. The possible value depend on
397 your compiler, for clang the value can be an absolute path to your custom
398 linker, otherwise clang will prefix the name with ``ld.`` and apply its usual
399 search. For example to link LLVM with the Gold linker, cmake can be invoked
400 with ``-DLLVM_USE_LINKER=gold``.
402 **LLVM_ENABLE_LLD**:BOOL
403 This option is equivalent to `-DLLVM_USE_LINKER=lld`, except during a 2-stage
404 build where a dependency is added from the first stage to the second ensuring
405 that lld is built before stage2 begins.
407 **LLVM_PARALLEL_COMPILE_JOBS**:STRING
408 Define the maximum number of concurrent compilation jobs.
410 **LLVM_PARALLEL_LINK_JOBS**:STRING
411 Define the maximum number of concurrent link jobs.
413 **LLVM_BUILD_DOCS**:BOOL
414 Adds all *enabled* documentation targets (i.e. Doxgyen and Sphinx targets) as
415 dependencies of the default build targets. This results in all of the (enabled)
416 documentation targets being as part of a normal build. If the ``install``
417 target is run then this also enables all built documentation targets to be
418 installed. Defaults to OFF. To enable a particular documentation target, see
419 see LLVM_ENABLE_SPHINX and LLVM_ENABLE_DOXYGEN.
421 **LLVM_ENABLE_DOXYGEN**:BOOL
422 Enables the generation of browsable HTML documentation using doxygen.
425 **LLVM_ENABLE_DOXYGEN_QT_HELP**:BOOL
426 Enables the generation of a Qt Compressed Help file. Defaults to OFF.
427 This affects the make target ``doxygen-llvm``. When enabled, apart from
428 the normal HTML output generated by doxygen, this will produce a QCH file
429 named ``org.llvm.qch``. You can then load this file into Qt Creator.
430 This option is only useful in combination with ``-DLLVM_ENABLE_DOXYGEN=ON``;
431 otherwise this has no effect.
433 **LLVM_DOXYGEN_QCH_FILENAME**:STRING
434 The filename of the Qt Compressed Help file that will be generated when
435 ``-DLLVM_ENABLE_DOXYGEN=ON`` and
436 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON`` are given. Defaults to
438 This option is only useful in combination with
439 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
440 otherwise it has no effect.
442 **LLVM_DOXYGEN_QHP_NAMESPACE**:STRING
443 Namespace under which the intermediate Qt Help Project file lives. See `Qt
445 for more information. Defaults to "org.llvm". This option is only useful in
446 combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise
449 **LLVM_DOXYGEN_QHP_CUST_FILTER_NAME**:STRING
450 See `Qt Help Project`_ for
451 more information. Defaults to the CMake variable ``${PACKAGE_STRING}`` which
452 is a combination of the package name and version string. This filter can then
453 be used in Qt Creator to select only documentation from LLVM when browsing
454 through all the help files that you might have loaded. This option is only
455 useful in combination with ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``;
456 otherwise it has no effect.
458 .. _Qt Help Project: http://qt-project.org/doc/qt-4.8/qthelpproject.html#custom-filters
460 **LLVM_DOXYGEN_QHELPGENERATOR_PATH**:STRING
461 The path to the ``qhelpgenerator`` executable. Defaults to whatever CMake's
462 ``find_program()`` can find. This option is only useful in combination with
463 ``-DLLVM_ENABLE_DOXYGEN_QT_HELP=ON``; otherwise it has no
466 **LLVM_DOXYGEN_SVG**:BOOL
467 Uses .svg files instead of .png files for graphs in the Doxygen output.
470 **LLVM_INSTALL_DOXYGEN_HTML_DIR**:STRING
471 The path to install Doxygen-generated HTML documentation to. This path can
472 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
473 `share/doc/llvm/doxygen-html`.
475 **LLVM_ENABLE_SPHINX**:BOOL
476 If specified, CMake will search for the ``sphinx-build`` executable and will make
477 the ``SPHINX_OUTPUT_HTML`` and ``SPHINX_OUTPUT_MAN`` CMake options available.
480 **SPHINX_EXECUTABLE**:STRING
481 The path to the ``sphinx-build`` executable detected by CMake.
482 For installation instructions, see
483 http://www.sphinx-doc.org/en/latest/install.html
485 **SPHINX_OUTPUT_HTML**:BOOL
486 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) then the targets for
487 building the documentation as html are added (but not built by default unless
488 ``LLVM_BUILD_DOCS`` is enabled). There is a target for each project in the
489 source tree that uses sphinx (e.g. ``docs-llvm-html``, ``docs-clang-html``
490 and ``docs-lld-html``). Defaults to ON.
492 **SPHINX_OUTPUT_MAN**:BOOL
493 If enabled (and ``LLVM_ENABLE_SPHINX`` is enabled) the targets for building
494 the man pages are added (but not built by default unless ``LLVM_BUILD_DOCS``
495 is enabled). Currently the only target added is ``docs-llvm-man``. Defaults
498 **SPHINX_WARNINGS_AS_ERRORS**:BOOL
499 If enabled then sphinx documentation warnings will be treated as
500 errors. Defaults to ON.
502 **LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
503 The path to install Sphinx-generated HTML documentation to. This path can
504 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
505 `share/doc/llvm/html`.
507 **LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
508 The path to install OCamldoc-generated HTML documentation to. This path can
509 either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
510 `share/doc/llvm/ocaml-html`.
512 **LLVM_CREATE_XCODE_TOOLCHAIN**:BOOL
513 OS X Only: If enabled CMake will generate a target named
514 'install-xcode-toolchain'. This target will create a directory at
515 $CMAKE_INSTALL_PREFIX/Toolchains containing an xctoolchain directory which can
516 be used to override the default system tools.
518 **LLVM_BUILD_LLVM_DYLIB**:BOOL
519 If enabled, the target for building the libLLVM shared library is added.
520 This library contains all of LLVM's components in a single shared library.
521 Defaults to OFF. This cannot be used in conjunction with BUILD_SHARED_LIBS.
522 Tools will only be linked to the libLLVM shared library if LLVM_LINK_LLVM_DYLIB
524 The components in the library can be customised by setting LLVM_DYLIB_COMPONENTS
525 to a list of the desired components.
527 **LLVM_LINK_LLVM_DYLIB**:BOOL
528 If enabled, tools will be linked with the libLLVM shared library. Defaults
529 to OFF. Setting LLVM_LINK_LLVM_DYLIB to ON also sets LLVM_BUILD_LLVM_DYLIB
532 **BUILD_SHARED_LIBS**:BOOL
533 Flag indicating if each LLVM component (e.g. Support) is built as a shared
534 library (ON) or as a static library (OFF). Its default value is OFF. On
535 Windows, shared libraries may be used when building with MinGW, including
536 mingw-w64, but not when building with the Microsoft toolchain.
538 .. note:: BUILD_SHARED_LIBS is only recommended for use by LLVM developers.
539 If you want to build LLVM as a shared library, you should use the
540 ``LLVM_BUILD_LLVM_DYLIB`` option.
542 **LLVM_OPTIMIZED_TABLEGEN**:BOOL
543 If enabled and building a debug or asserts build the CMake build system will
544 generate a Release build tree to build a fully optimized tablegen for use
545 during the build. Enabling this option can significantly speed up build times
546 especially when building LLVM in Debug configurations.
548 **LLVM_REVERSE_ITERATION**:BOOL
549 If enabled, all supported unordered llvm containers would be iterated in
550 reverse order. This is useful for uncovering non-determinism caused by
551 iteration of unordered containers.
553 **LLVM_BUILD_INSTRUMENTED_COVERAGE**:BOOL
554 If enabled, `source-based code coverage
555 <http://clang.llvm.org/docs/SourceBasedCodeCoverage.html>`_ instrumentation
556 is enabled while building llvm.
558 **LLVM_CCACHE_BUILD**:BOOL
559 If enabled and the ``ccache`` program is available, then LLVM will be
560 built using ``ccache`` to speed up rebuilds of LLVM and its components.
561 Defaults to OFF. The size and location of the cache maintained
562 by ``ccache`` can be adjusted via the LLVM_CCACHE_MAXSIZE and LLVM_CCACHE_DIR
563 options, which are passed to the CCACHE_MAXSIZE and CCACHE_DIR environment
564 variables, respectively.
569 Recently LLVM and Clang have been adding some more complicated build system
570 features. Utilizing these new features often involves a complicated chain of
571 CMake variables passed on the command line. Clang provides a collection of CMake
572 cache scripts to make these features more approachable.
574 CMake cache files are utilized using CMake's -C flag:
576 .. code-block:: console
578 $ cmake -C <path to cache file> <path to sources>
580 CMake cache scripts are processed in an isolated scope, only cached variables
581 remain set when the main configuration runs. CMake cached variables do not reset
582 variables that are already set unless the FORCE option is specified.
584 A few notes about CMake Caches:
586 - Order of command line arguments is important
588 - -D arguments specified before -C are set before the cache is processed and
589 can be read inside the cache file
590 - -D arguments specified after -C are set after the cache is processed and
591 are unset inside the cache file
593 - All -D arguments will override cache file settings
594 - CMAKE_TOOLCHAIN_FILE is evaluated after both the cache file and the command
596 - It is recommended that all -D options should be specified *before* -C
598 For more information about some of the advanced build configurations supported
599 via Cache files see :doc:`AdvancedBuilds`.
601 Executing the test suite
602 ========================
604 Testing is performed when the *check-all* target is built. For instance, if you are
605 using Makefiles, execute this command in the root of your build directory:
607 .. code-block:: console
611 On Visual Studio, you may run tests by building the project "check-all".
612 For more information about testing, see the :doc:`TestingGuide`.
617 See `this wiki page <http://www.vtk.org/Wiki/CMake_Cross_Compiling>`_ for
618 generic instructions on how to cross-compile with CMake. It goes into detailed
619 explanations and may seem daunting, but it is not. On the wiki page there are
620 several examples including toolchain files. Go directly to `this section
621 <http://www.vtk.org/Wiki/CMake_Cross_Compiling#Information_how_to_set_up_various_cross_compiling_toolchains>`_
622 for a quick solution.
624 Also see the `LLVM-specific variables`_ section for variables used when
627 Embedding LLVM in your project
628 ==============================
630 From LLVM 3.5 onwards both the CMake and autoconf/Makefile build systems export
631 LLVM libraries as importable CMake targets. This means that clients of LLVM can
632 now reliably use CMake to develop their own LLVM-based projects against an
633 installed version of LLVM regardless of how it was built.
635 Here is a simple example of a CMakeLists.txt file that imports the LLVM libraries
636 and uses them to build a simple application ``simple-tool``.
638 .. code-block:: cmake
640 cmake_minimum_required(VERSION 3.4.3)
641 project(SimpleProject)
643 find_package(LLVM REQUIRED CONFIG)
645 message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
646 message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
648 # Set your project compile flags.
649 # E.g. if using the C++ header files
650 # you will need to enable C++11 support
653 include_directories(${LLVM_INCLUDE_DIRS})
654 add_definitions(${LLVM_DEFINITIONS})
656 # Now build our tools
657 add_executable(simple-tool tool.cpp)
659 # Find the libraries that correspond to the LLVM components
660 # that we wish to use
661 llvm_map_components_to_libnames(llvm_libs support core irreader)
663 # Link against LLVM libraries
664 target_link_libraries(simple-tool ${llvm_libs})
666 The ``find_package(...)`` directive when used in CONFIG mode (as in the above
667 example) will look for the ``LLVMConfig.cmake`` file in various locations (see
668 cmake manual for details). It creates a ``LLVM_DIR`` cache entry to save the
669 directory where ``LLVMConfig.cmake`` is found or allows the user to specify the
670 directory (e.g. by passing ``-DLLVM_DIR=/usr/lib/cmake/llvm`` to
671 the ``cmake`` command or by setting it directly in ``ccmake`` or ``cmake-gui``).
673 This file is available in two different locations.
675 * ``<INSTALL_PREFIX>/lib/cmake/llvm/LLVMConfig.cmake`` where
676 ``<INSTALL_PREFIX>`` is the install prefix of an installed version of LLVM.
677 On Linux typically this is ``/usr/lib/cmake/llvm/LLVMConfig.cmake``.
679 * ``<LLVM_BUILD_ROOT>/lib/cmake/llvm/LLVMConfig.cmake`` where
680 ``<LLVM_BUILD_ROOT>`` is the root of the LLVM build tree. **Note: this is only
681 available when building LLVM with CMake.**
683 If LLVM is installed in your operating system's normal installation prefix (e.g.
684 on Linux this is usually ``/usr/``) ``find_package(LLVM ...)`` will
685 automatically find LLVM if it is installed correctly. If LLVM is not installed
686 or you wish to build directly against the LLVM build tree you can use
687 ``LLVM_DIR`` as previously mentioned.
689 The ``LLVMConfig.cmake`` file sets various useful variables. Notable variables
693 The path to the LLVM CMake directory (i.e. the directory containing
697 A list of preprocessor defines that should be used when building against LLVM.
699 ``LLVM_ENABLE_ASSERTIONS``
700 This is set to ON if LLVM was built with assertions, otherwise OFF.
703 This is set to ON if LLVM was built with exception handling (EH) enabled,
707 This is set to ON if LLVM was built with run time type information (RTTI),
710 ``LLVM_INCLUDE_DIRS``
711 A list of include paths to directories containing LLVM header files.
713 ``LLVM_PACKAGE_VERSION``
714 The LLVM version. This string can be used with CMake conditionals, e.g., ``if
715 (${LLVM_PACKAGE_VERSION} VERSION_LESS "3.5")``.
717 ``LLVM_TOOLS_BINARY_DIR``
718 The path to the directory containing the LLVM tools (e.g. ``llvm-as``).
720 Notice that in the above example we link ``simple-tool`` against several LLVM
721 libraries. The list of libraries is determined by using the
722 ``llvm_map_components_to_libnames()`` CMake function. For a list of available
723 components look at the output of running ``llvm-config --components``.
725 Note that for LLVM < 3.5 ``llvm_map_components_to_libraries()`` was
726 used instead of ``llvm_map_components_to_libnames()``. This is now deprecated
727 and will be removed in a future version of LLVM.
729 .. _cmake-out-of-source-pass:
731 Developing LLVM passes out of source
732 ------------------------------------
734 It is possible to develop LLVM passes out of LLVM's source tree (i.e. against an
735 installed or built LLVM). An example of a project layout is provided below.
748 Contents of ``<project dir>/CMakeLists.txt``:
750 .. code-block:: cmake
752 find_package(LLVM REQUIRED CONFIG)
754 add_definitions(${LLVM_DEFINITIONS})
755 include_directories(${LLVM_INCLUDE_DIRS})
757 add_subdirectory(<pass name>)
759 Contents of ``<project dir>/<pass name>/CMakeLists.txt``:
761 .. code-block:: cmake
763 add_library(LLVMPassname MODULE Pass.cpp)
765 Note if you intend for this pass to be merged into the LLVM source tree at some
766 point in the future it might make more sense to use LLVM's internal
767 ``add_llvm_loadable_module`` function instead by...
770 Adding the following to ``<project dir>/CMakeLists.txt`` (after
771 ``find_package(LLVM ...)``)
773 .. code-block:: cmake
775 list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
778 And then changing ``<project dir>/<pass name>/CMakeLists.txt`` to
780 .. code-block:: cmake
782 add_llvm_loadable_module(LLVMPassname
786 When you are done developing your pass, you may wish to integrate it
787 into the LLVM source tree. You can achieve it in two easy steps:
789 #. Copying ``<pass name>`` folder into ``<LLVM root>/lib/Transform`` directory.
791 #. Adding ``add_subdirectory(<pass name>)`` line into
792 ``<LLVM root>/lib/Transform/CMakeLists.txt``.
794 Compiler/Platform-specific topics
795 =================================
797 Notes for specific compilers and/or platforms.
802 **LLVM_COMPILER_JOBS**:STRING
803 Specifies the maximum number of parallel compiler jobs to use per project
804 when building with msbuild or Visual Studio. Only supported for the Visual
805 Studio 2010 CMake generator. 0 means use all processors. Default is 0.