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16<h1>Getting Started: Building and Running Clang</h1>
17
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]18<p>This page gives you the shortest path to checking out Clang and demos a few
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]19options. This should get you up and running with the minimum of muss and fuss.
20If you like what you see, please consider <a href="get_involved.html">getting
Chris Lattnerd2c1c602009-11-09 03:18:18 +0000[diff] [blame]21involved</a> with the Clang community. If you run into problems, please file
Douglas Gregor9ff3e662010-10-07 20:20:57 +0000[diff] [blame]22bugs in <a href="http://llvm.org/bugs/">LLVM Bugzilla</a>.</p>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]23
Daniel Dunbarfa8e11b2010-11-02 22:34:04 +0000[diff] [blame]24<h2 id="download">Release Clang Versions</h2>
25
26<p>Clang has been released as part of regular LLVM releases since LLVM 2.6. You
27can download the release versions
28from <a href="http://llvm.org/releases/">http://llvm.org/releases/</a>.</p>
29
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]30<h2 id="build">Building Clang and Working with the Code</h2>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]31
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]32<h3 id="buildNix">On Unix-like Systems</h3>
33
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]34<p>If you would like to check out and build Clang, the current procedure is as
35follows:</p>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]36
37<ol>
Anton Korobeynikov1816e482009-08-06 13:00:08 +0000[diff] [blame]38 <li>Get the required tools.
39 <ul>
40 <li>See
41 <a href="http://llvm.org/docs/GettingStarted.html#requirements">
42 Getting Started with the LLVM System - Requirements</a>.</li>
43 <li>Note also that Python is needed for running the test suite.
44 Get it at: <a href="http://www.python.org/download">
45 http://www.python.org/download</a></li>
46 </ul>
47
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]48 <li>Checkout LLVM:</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]49 <ul>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]50 <li>Change directory to where you want the llvm directory placed.</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]51 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]52 </ul>
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]53 <li>Checkout Clang:</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]54 <ul>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]55 <li><tt>cd llvm/tools</tt>
56 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
57 </ul>
Daniel Dunbar078f8592011-12-07 03:04:42 +0000[diff] [blame^]58 <li>Checkout Compiler-RT:</li>
59 <ul>
60 <li><tt>cd llvm/projects</tt>
61 <li><tt>svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk
62 compiler-rt</tt></li>
63 </ul>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]64 <li>Build LLVM and Clang:</li>
65 <ul>
Rafael Espindolafa5fa972010-10-29 22:05:17 +0000[diff] [blame]66 <li><tt>cd ../..</tt> (back to where you started)</li>
67 <li><tt>mkdir build</tt> (for building without polluting the source dir)
68 </li>
69 <li><tt>cd build</tt></li>
70 <li><tt>../llvm/configure</tt></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]71 <li><tt>make</tt></li>
72 <li>This builds both LLVM and Clang for debug mode.</li>
73 <li>Note: For subsequent Clang development, you can just do make at the
74 clang directory level.</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]75 </ul>
Chris Lattner78781782010-05-06 21:57:57 +0000[diff] [blame]76
77 <p>It is also possible to use CMake instead of the makefiles. With CMake it
78 is also possible to generate project files for several IDEs: Eclipse CDT4,
79 CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3.</p>
80
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]81 <li>If you intend to work on Clang C++ support, you may need to tell it how
82 to find your C++ standard library headers. If Clang cannot find your
Chris Lattnerca8c49f2009-03-10 16:01:44 +0000[diff] [blame]83 system libstdc++ headers, please follow these instructions:</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]84 <ul>
Gabor Greif74350822010-03-29 21:36:06 +0000[diff] [blame]85 <li>'<tt>gcc -v -x c++ /dev/null -fsyntax-only</tt>' to get the
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]86 path.</li>
87 <li>Look for the comment "FIXME: temporary hack:
Chris Lattnerca8c49f2009-03-10 16:01:44 +0000[diff] [blame]88 hard-coded paths" in <tt>clang/lib/Frontend/InitHeaderSearch.cpp</tt> and
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]89 change the lines below to include that path.</li>
90 </ul>
Chris Lattnerbe9a5ca2010-07-26 22:51:00 +0000[diff] [blame]91 <li>Try it out (assuming you add llvm/Debug+Asserts/bin to your path):</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]92 <ul>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]93 <li><tt>clang --help</tt></li>
94 <li><tt>clang file.c -fsyntax-only</tt> (check for correctness)</li>
95 <li><tt>clang file.c -S -emit-llvm -o -</tt> (print out unoptimized llvm code)</li>
96 <li><tt>clang file.c -S -emit-llvm -o - -O3</tt></li>
97 <li><tt>clang file.c -S -O3 -o -</tt> (output native machine code)</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]98 </ul>
99</ol>
100
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]101<p>Note that the C front-end uses LLVM, but does not depend on llvm-gcc. If you
102encounter problems with building Clang, make sure you have the latest SVN
103version of LLVM. LLVM contains support libraries for Clang that will be updated
104as well as development on Clang progresses.</p>
Ted Kremenek675a9ba2008-02-08 07:32:26 +0000[diff] [blame]105
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]106<h3>Simultaneously Building Clang and LLVM:</h3>
Eric Christopher562b4f32008-02-08 07:10:48 +0000[diff] [blame]107
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]108<p>Once you have checked out Clang into the llvm source tree it will build along
109with the rest of <tt>llvm</tt>. To build all of LLVM and Clang together all at
110once simply run <tt>make</tt> from the root LLVM directory.</p>
111
112<p><em>Note:</em> Observe that Clang is technically part of a separate
113Subversion repository. As mentioned above, the latest Clang sources are tied to
114the latest sources in the LLVM tree. You can update your toplevel LLVM project
115and all (possibly unrelated) projects inside it with <tt><b>make
116update</b></tt>. This will run <tt>svn update</tt> on all subdirectories related
117to subversion. </p>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]118
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]119<h3 id="buildWindows">Using Visual Studio</h3>
120
121<p>The following details setting up for and building Clang on Windows using
122Visual Studio:</p>
123
124<ol>
125 <li>Get the required tools:</li>
126 <ul>
127 <li><b>Subversion</b>. Source code control program. Get it from:
128 <a href="http://subversion.tigris.org/getting.html">
129 http://subversion.tigris.org/getting.html</a></li>
130 <li><b>cmake</b>. This is used for generating Visual Studio solution and
131 project files. Get it from:
132 <a href="http://www.cmake.org/cmake/resources/software.html">
133 http://www.cmake.org/cmake/resources/software.html</a></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]134 <li><b>Visual Studio 2008 or 2010</b></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]135 <li><b>Python</b>. This is needed only if you will be running the tests
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]136 (which is essential, if you will be developing for clang).
137 Get it from:
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]138 <a href="http://www.python.org/download/">
139 http://www.python.org/download/</a></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]140 <li><b>GnuWin32 tools</b>
141 These are also necessary for running the tests.
142 (Note that the grep from MSYS or Cygwin doesn't work with the tests
143 because of embedded double-quotes in the search strings. The GNU
144 grep does work in this case.)
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]145 Get them from <a href="http://getgnuwin32.sourceforge.net/">
146 http://getgnuwin32.sourceforge.net/</a>.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]147 </ul>
148
149 <li>Checkout LLVM:</li>
150 <ul>
151 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
152 </ul>
153 <li>Checkout Clang:</li>
154 <ul>
155 <li><tt>cd llvm\tools</tt>
156 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
157 </ul>
158 <li>Run cmake to generate the Visual Studio solution and project files:</li>
159 <ul>
Michael J. Spencer0de57862010-12-16 22:01:14 +0000[diff] [blame]160 <li><tt>cd ..\..</tt> (back to where you started)</li>
161 <li><tt>mkdir build</tt> (for building without polluting the source dir)</li>
162 <li><tt>cd build</tt></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]163 <li>If you are using Visual Studio 2008: <tt>cmake -G "Visual Studio 9 2008" ..\llvm</tt></li>
Michael J. Spencer0de57862010-12-16 22:01:14 +0000[diff] [blame]164 <li>Or if you are using Visual Studio 2010: <tt>cmake -G "Visual Studio 10" ..\llvm</tt></li>
John Thompson13eb5652011-04-06 18:22:12 +0000[diff] [blame]165 <li>By default, cmake will target LLVM to X86. If you want all targets
166 (needed if you want to run the LLVM tests), add the <tt>-DLLVM_TARGETS_TO_BUILD=all</tt> option to the
167 cmake command line. Or specify a target from the LLVM_TARGETS_TO_BUILD
168 definition in CMakeLists.txt.</li>
169 <li>See the <a href="http://www.llvm.org/docs/CMake.html">LLVM CMake guide</a> for
170 more information on other configuration options for cmake.</li>
171</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]172 <li>The above, if successful, will have created an LLVM.sln file in the
NAKAMURA Takumi542c7622011-07-25 12:40:26 +0000[diff] [blame]173 <tt>build</tt> directory.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]174 </ul>
175 <li>Build Clang:</li>
176 <ul>
177 <li>Open LLVM.sln in Visual Studio.</li>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]178 <li>Build the "clang" project for just the compiler driver and front end, or
179 the "ALL_BUILD" project to build everything, including tools.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]180 </ul>
181 <li>Try it out (assuming you added llvm/debug/bin to your path). (See the
182 running examples from above.)</li>
183 <li>See <a href="hacking.html#testingWindows">
184 Hacking on clang - Testing using Visual Studio on Windows</a> for information
185 on running regression tests on Windows.</li>
186</ol>
187
188<p>Note that once you have checked out both llvm and clang, to synchronize
189to the latest code base, use the <tt>svn update</tt> command in both the
190llvm and llvm\tools\clang directories, as they are separate repositories.</p>
191
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]192<a name="driver"><h2>Clang Compiler Driver (Drop-in Substitute for GCC)</h2></a>
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]193
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]194<p>The <tt>clang</tt> tool is the compiler driver and front-end, which is
195designed to be a drop-in replacement for the <tt>gcc</tt> command. Here are
196some examples of how to use the high-level driver:
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]197</p>
198
199<pre class="code">
200$ <b>cat t.c</b>
201#include &lt;stdio.h&gt;
202int main(int argc, char **argv) { printf("hello world\n"); }
203$ <b>clang t.c</b>
204$ <b>./a.out</b>
205hello world
206</pre>
207
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]208<p>The 'clang' driver is designed to work as closely to GCC as possible to
209 maximize portability. The only major difference between the two is that
210 Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see
Chris Lattnerd73fef62009-11-09 04:04:07 +0000[diff] [blame]211 weird link-time errors relating to inline functions, try passing -std=gnu89
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]212 to clang.</p>
213
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]214<h2>Examples of using Clang</h2>
215
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]216<!-- Thanks to
217 http://shiflett.org/blog/2006/oct/formatting-and-highlighting-php-code-listings
218Site suggested using pre in CSS, but doesn't work in IE, so went for the <pre>
219tag. -->
220
221<pre class="code">
222$ <b>cat ~/t.c</b>
223typedef float V __attribute__((vector_size(16)));
224V foo(V a, V b) { return a+b*a; }
225</pre>
226
227
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]228<h3>Preprocessing:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]229
230<pre class="code">
231$ <b>clang ~/t.c -E</b>
232# 1 "/Users/sabre/t.c" 1
233
234typedef float V __attribute__((vector_size(16)));
235
236V foo(V a, V b) { return a+b*a; }
237</pre>
238
239
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]240<h3>Type checking:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]241
242<pre class="code">
243$ <b>clang -fsyntax-only ~/t.c</b>
244</pre>
245
246
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]247<h3>GCC options:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]248
249<pre class="code">
250$ <b>clang -fsyntax-only ~/t.c -pedantic</b>
David Blaikie19ff92b2011-11-07 06:28:33 +0000[diff] [blame]251/Users/sabre/t.c:2:17: <font color="magenta">warning:</font> extension used
252<font color="darkgreen">typedef float V __attribute__((vector_size(16)));</font>
253<font color="blue"> ^</font>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]2541 diagnostic generated.
255</pre>
256
257
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]258<h3>Pretty printing from the AST:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]259
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]260<p>Note, the <tt>-cc1</tt> argument indicates the the compiler front-end, and
261not the driver, should be run. The compiler front-end has several additional
262Clang specific features which are not exposed through the GCC compatible driver
263interface.</p>
264
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]265<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]266$ <b>clang -cc1 ~/t.c -ast-print</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]267typedef float V __attribute__(( vector_size(16) ));
268V foo(V a, V b) {
269 return a + b * a;
270}
271</pre>
272
273
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]274<h3>Code generation with LLVM:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]275
276<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]277$ <b>clang ~/t.c -S -emit-llvm -o -</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]278define &lt;4 x float&gt; @foo(&lt;4 x float&gt; %a, &lt;4 x float&gt; %b) {
279entry:
280 %mul = mul &lt;4 x float&gt; %b, %a
281 %add = add &lt;4 x float&gt; %mul, %a
282 ret &lt;4 x float&gt; %add
283}
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]284$ <b>clang -fomit-frame-pointer -O3 -S -o - t.c</b> <i># On x86_64</i>
285...
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]286_foo:
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]287Leh_func_begin1:
288 mulps %xmm0, %xmm1
289 addps %xmm1, %xmm0
290 ret
291Leh_func_end1:
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]292</pre>
293
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]294</div>
295</body>
296</html>