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5 <title>Building LLVM with CMake</title>
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9 <div class="doc_title">
10 Building LLVM with CMake
14 <li><a href="#intro">Introduction</a></li>
15 <li><a href="#quickstart">Quick start</a></li>
16 <li><a href="#usage">Basic CMake usage</a>
17 <li><a href="#options">Options and variables</a>
19 <li><a href="#freccmake">Frequently-used CMake variables</a></li>
20 <li><a href="#llvmvars">LLVM-specific variables</a></li>
22 <li><a href="#testing">Executing the test suite</a>
23 <li><a href="#cross">Cross compiling</a>
24 <li><a href="#embedding">Embedding LLVM in your project</a>
25 <li><a href="#specifics">Compiler/Platform specific topics</a>
27 <li><a href="#msvc">Microsoft Visual C++</a></li>
31 <div class="doc_author">
32 <p>Written by <a href="mailto:ofv@wanadoo.es">Oscar Fuentes</a></p>
35 <!-- *********************************************************************** -->
36 <div class="doc_section">
37 <a name="intro">Introduction</a>
39 <!-- *********************************************************************** -->
41 <div class="doc_text">
43 <p><a href="http://www.cmake.org/">CMake</a> is a cross-platform
44 build-generator tool. CMake does not build the project, it generates
45 the files needed by your build tool (GNU make, Visual Studio, etc) for
48 <p>If you are really anxious about getting a functional LLVM build,
49 go to the <a href="#quickstart">Quick start</a> section. If you
50 are a CMake novice, start on <a href="#usage">Basic CMake
51 usage</a> and then go back to the <a href="#quickstart">Quick
52 start</a> once you know what you are
53 doing. The <a href="#options">Options and variables</a> section
54 is a reference for customizing your build. If you already have
55 experience with CMake, this is the recommended starting point.
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59 <div class="doc_section">
60 <a name="quickstart">Quick start</a>
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64 <div class="doc_text">
66 <p> We use here the command-line, non-interactive CMake interface </p>
70 <li><p><a href="http://www.cmake.org/cmake/resources/software.html">Download</a>
71 and install CMake. Version 2.6.2 is the minimum required.</p>
73 <li><p>Open a shell. Your development tools must be reachable from this
74 shell through the PATH environment variable.</p>
76 <li><p>Create a directory for containing the build. It is not
77 supported to build LLVM on the source directory. cd to this
79 <div class="doc_code">
80 <p><tt>mkdir mybuilddir</tt></p>
81 <p><tt>cd mybuilddir</tt></p>
84 <li><p>Execute this command on the shell
85 replacing <i>path/to/llvm/source/root</i> with the path to the
86 root of your LLVM source tree:</p>
87 <div class="doc_code">
88 <p><tt>cmake path/to/llvm/source/root</tt></p>
91 <p>CMake will detect your development environment, perform a
92 series of test and generate the files required for building
93 LLVM. CMake will use default values for all build
94 parameters. See the <a href="#options">Options and variables</a>
95 section for fine-tuning your build</p>
97 <p>This can fail if CMake can't detect your toolset, or if it
98 thinks that the environment is not sane enough. On this case
99 make sure that the toolset that you intend to use is the only
100 one reachable from the shell and that the shell itself is the
101 correct one for you development environment. CMake will refuse
102 to build MinGW makefiles if you have a POSIX shell reachable
103 through the PATH environment variable, for instance. You can
104 force CMake to use a given build tool, see
105 the <a href="#usage">Usage</a> section.</p>
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112 <div class="doc_section">
113 <a name="usage">Basic CMake usage</a>
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117 <div class="doc_text">
119 <p>This section explains basic aspects of CMake, mostly for
120 explaining those options which you may need on your day-to-day
123 <p>CMake comes with extensive documentation in the form of html
124 files and on the cmake executable itself. Execute <i>cmake
125 --help</i> for further help options.</p>
127 <p>CMake requires to know for which build tool it shall generate
128 files (GNU make, Visual Studio, Xcode, etc). If not specified on
129 the command line, it tries to guess it based on you
130 environment. Once identified the build tool, CMake uses the
131 corresponding <i>Generator</i> for creating files for your build
132 tool. You can explicitly specify the generator with the command
133 line option <i>-G "Name of the generator"</i>. For knowing the
134 available generators on your platform, execute</p>
136 <div class="doc_code">
137 <p><tt>cmake --help</tt></p>
140 <p>This will list the generator's names at the end of the help
141 text. Generator's names are case-sensitive. Example:</p>
143 <div class="doc_code">
144 <p><tt>cmake -G "Visual Studio 8 2005" path/to/llvm/source/root</tt></p>
147 <p>For a given development platform there can be more than one
148 adequate generator. If you use Visual Studio "NMake Makefiles"
149 is a generator you can use for building with NMake. By default,
150 CMake chooses the more specific generator supported by your
151 development environment. If you want an alternative generator,
152 you must tell this to CMake with the <i>-G</i> option.</p>
154 <p>TODO: explain variables and cache. Move explanation here from
155 #options section.</p>
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160 <div class="doc_section">
161 <a name="options">Options and variables</a>
163 <!-- *********************************************************************** -->
165 <div class="doc_text">
167 <p>Variables customize how the build will be generated. Options are
168 boolean variables, with possible values ON/OFF. Options and
169 variables are defined on the CMake command line like this:</p>
171 <div class="doc_code">
172 <p><tt>cmake -DVARIABLE=value path/to/llvm/source</tt></p>
175 <p>You can set a variable after the initial CMake invocation for
176 changing its value. You can also undefine a variable:</p>
178 <div class="doc_code">
179 <p><tt>cmake -UVARIABLE path/to/llvm/source</tt></p>
182 <p>Variables are stored on the CMake cache. This is a file
183 named <tt>CMakeCache.txt</tt> on the root of the build
184 directory. Do not hand-edit it.</p>
186 <p>Variables are listed here appending its type after a colon. It is
187 correct to write the variable and the type on the CMake command
190 <div class="doc_code">
191 <p><tt>cmake -DVARIABLE:TYPE=value path/to/llvm/source</tt></p>
196 <!-- ======================================================================= -->
197 <div class="doc_subsection">
198 <a name="freccmake">Frequently-used CMake variables</a>
201 <div class="doc_text">
203 <p>Here are listed some of the CMake variables that are used often,
204 along with a brief explanation and LLVM-specific notes. For full
205 documentation, check the CMake docs or execute <i>cmake
206 --help-variable VARIABLE_NAME</i>.</p>
209 <dt><b>CMAKE_BUILD_TYPE</b>:STRING</dt>
211 <dd>Sets the build type for <i>make</i> based generators. Possible
212 values are Release, Debug, RelWithDebInfo and MinSizeRel. On
213 systems like Visual Studio the user sets the build type with the IDE
216 <dt><b>CMAKE_INSTALL_PREFIX</b>:PATH</dt>
217 <dd>Path where LLVM will be installed if "make install" is invoked
218 or the "INSTALL" target is built.</dd>
220 <dt><b>LLVM_LIBDIR_SUFFIX</b>:STRING</dt>
221 <dd>Extra suffix to append to the directory where libraries are to
222 be installed. On a 64-bit architecture, one could use
223 -DLLVM_LIBDIR_SUFFIX=64 to install libraries to /usr/lib64.</dd>
225 <dt><b>CMAKE_C_FLAGS</b>:STRING</dt>
226 <dd>Extra flags to use when compiling C source files.</dd>
228 <dt><b>CMAKE_CXX_FLAGS</b>:STRING</dt>
229 <dd>Extra flags to use when compiling C++ source files.</dd>
231 <dt><b>BUILD_SHARED_LIBS</b>:BOOL</dt>
232 <dd>Flag indicating is shared libraries will be built. Its default
233 value is OFF. Shared libraries are not supported on Windows and
234 not recommended in the other OSes.</dd>
239 <!-- ======================================================================= -->
240 <div class="doc_subsection">
241 <a name="llvmvars">LLVM-specific variables</a>
244 <div class="doc_text">
247 <dt><b>LLVM_TARGETS_TO_BUILD</b>:STRING</dt>
248 <dd>Semicolon-separated list of targets to build, or <i>all</i> for
249 building all targets. Case-sensitive. For Visual C++ defaults
250 to <i>X86</i>. On the other cases defaults to <i>all</i>. Example:
251 <i>-DLLVM_TARGETS_TO_BUILD="X86;PowerPC;Alpha"</i>.</dd>
253 <dt><b>LLVM_BUILD_TOOLS</b>:BOOL</dt>
254 <dd>Build LLVM tools. Defaults to ON. Targets for building each tool
255 are generated in any case. You can build an tool separately by
256 invoking its target. For example, you can build <i>llvm-as</i>
257 with a makefile-based system executing <i>make llvm-as</i> on the
258 root of your build directory.</dd>
260 <dt><b>LLVM_BUILD_EXAMPLES</b>:BOOL</dt>
261 <dd>Build LLVM examples. Defaults to OFF. Targets for building each
262 example are generated in any case. See documentation
263 for <i>LLVM_BUILD_TOOLS</i> above for more details.</dd>
265 <dt><b>LLVM_ENABLE_THREADS</b>:BOOL</dt>
266 <dd>Build with threads support, if available. Defaults to ON.</dd>
268 <dt><b>LLVM_ENABLE_ASSERTIONS</b>:BOOL</dt>
269 <dd>Enables code assertions. Defaults to OFF if and only if
270 CMAKE_BUILD_TYPE is <i>Release</i>.</dd>
272 <dt><b>LLVM_ENABLE_PIC</b>:BOOL</dt>
273 <dd>Add the <i>-fPIC</i> flag for the compiler command-line, if the
274 compiler supports this flag. Some systems, like Windows, do not
275 need this flag. Defaults to ON.</dd>
277 <dt><b>LLVM_ENABLE_WARNINGS</b>:BOOL</dt>
278 <dd>Enable all compiler warnings. Defaults to ON.</dd>
280 <dt><b>LLVM_ENABLE_PEDANTIC</b>:BOOL</dt>
281 <dd>Enable pedantic mode. This disable compiler specific extensions, is
282 possible. Defaults to ON.</dd>
284 <dt><b>LLVM_ENABLE_WERROR</b>:BOOL</dt>
285 <dd>Stop and fail build, if a compiler warning is
286 triggered. Defaults to OFF.</dd>
288 <dt><b>LLVM_BUILD_32_BITS</b>:BOOL</dt>
289 <dd>Build 32-bits executables and libraries on 64-bits systems. This
290 option is available only on some 64-bits unix systems. Defaults to
293 <dt><b>LLVM_TARGET_ARCH</b>:STRING</dt>
294 <dd>LLVM target to use for native code generation. This is required
295 for JIT generation. It defaults to "host", meaning that it shall
296 pick the architecture of the machine where LLVM is being built. If
297 you are cross-compiling, set it to the target architecture
300 <dt><b>LLVM_TABLEGEN</b>:STRING</dt>
301 <dd>Full path to a native TableGen executable (usually
302 named <i>tblgen</i>). This is intented for cross-compiling: if the
303 user sets this variable, no native TableGen will be created.</dd>
308 <!-- *********************************************************************** -->
309 <div class="doc_section">
310 <a name="testing">Executing the test suite</a>
312 <!-- *********************************************************************** -->
314 <div class="doc_text">
316 <p>Testing is performed when the <i>check</i> target is built. For
317 instance, if you are using makefiles, execute this command while on
318 the top level of your build directory:</p>
320 <div class="doc_code">
321 <p><tt>make check</tt></p>
324 <p>Testing is not supported on Visual Studio.</p>
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329 <div class="doc_section">
330 <a name="cross">Cross compiling</a>
332 <!-- *********************************************************************** -->
334 <div class="doc_text">
336 <p>See <a href="http://www.vtk.org/Wiki/CMake_Cross_Compiling">this
337 wiki page</a> for generic instructions on how to cross-compile
338 with CMake. It goes into detailed explanations and may seem
339 daunting, but it is not. On the wiki page there are several
340 examples including toolchain files. Go directly to
341 <a href="http://www.vtk.org/Wiki/CMake_Cross_Compiling#Information_how_to_set_up_various_cross_compiling_toolchains">this
342 section</a> for a quick solution.</p>
344 <p>Also see the <a href="#llvmvars">LLVM-specific variables</a>
345 section for variables used when cross-compiling.</p>
349 <!-- *********************************************************************** -->
350 <div class="doc_section">
351 <a name="embedding">Embedding LLVM in your project</a>
353 <!-- *********************************************************************** -->
355 <div class="doc_text">
361 <!-- *********************************************************************** -->
363 <!-- *********************************************************************** -->
364 <div class="doc_section">
365 <a name="specifics">Compiler/Platform specific topics</a>
367 <!-- *********************************************************************** -->
369 <div class="doc_text">
371 <p>Notes for specific compilers and/or platforms.</p>
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384 <a href="mailto:ofv@wanadoo.es">Oscar Fuentes</a><br>
385 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
386 Last modified: $Date: 2008-12-31 03:59:36 +0100 (Wed, 31 Dec 2008) $