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Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]6 <title>Clang - Getting Started</title>
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12<!--#include virtual="menu.html.incl"-->
13
14<div id="content">
15
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
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]48 <li>Checkout LLVM:
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>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]53 </li>
54 <li>Checkout Clang:
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]55 <ul>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]56 <li><tt>cd llvm/tools</tt>
57 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
58 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]59 </li>
60 <li>Checkout Compiler-RT:
Daniel Dunbar078f8592011-12-07 03:04:42 +0000[diff] [blame]61 <ul>
Benjamin Kramerbf020bb2012-02-09 16:04:50 +0000[diff] [blame]62 <li><tt>cd ../..</tt> (back to where you started)</li>
Daniel Dunbar078f8592011-12-07 03:04:42 +0000[diff] [blame]63 <li><tt>cd llvm/projects</tt>
64 <li><tt>svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk
65 compiler-rt</tt></li>
66 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]67 </li>
68 <li>Build LLVM and Clang:
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]69 <ul>
Rafael Espindolafa5fa972010-10-29 22:05:17 +0000[diff] [blame]70 <li><tt>cd ../..</tt> (back to where you started)</li>
71 <li><tt>mkdir build</tt> (for building without polluting the source dir)
72 </li>
73 <li><tt>cd build</tt></li>
74 <li><tt>../llvm/configure</tt></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]75 <li><tt>make</tt></li>
76 <li>This builds both LLVM and Clang for debug mode.</li>
77 <li>Note: For subsequent Clang development, you can just do make at the
78 clang directory level.</li>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]79 <li>It is also possible to use CMake instead of the makefiles. With CMake
80 it is also possible to generate project files for several IDEs: Eclipse
81 CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3.</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]82 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]83 </li>
Chris Lattner78781782010-05-06 21:57:57 +0000[diff] [blame]84
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]85 <li>If you intend to work on Clang C++ support, you may need to tell it how
Chandler Carruthabccc1f2012-05-16 08:18:58 +0000[diff] [blame]86 to find your C++ standard library headers. In general, Clang will detect
87 the best version of libstdc++ headers available and use them - it will
88 look both for system installations of libstdc++ as well as installations
89 adjacent to Clang itself. If your configuration fits neither of these
90 scenarios, you can use the <tt>--with-gcc-toolchain</tt> configure option
91 to tell Clang where the gcc containing the desired libstdc++ is installed.
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]92 </li>
93 <li>Try it out (assuming you add llvm/Debug+Asserts/bin to your path):
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]94 <ul>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]95 <li><tt>clang --help</tt></li>
96 <li><tt>clang file.c -fsyntax-only</tt> (check for correctness)</li>
97 <li><tt>clang file.c -S -emit-llvm -o -</tt> (print out unoptimized llvm code)</li>
98 <li><tt>clang file.c -S -emit-llvm -o - -O3</tt></li>
99 <li><tt>clang file.c -S -O3 -o -</tt> (output native machine code)</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]100 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]101 </li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]102</ol>
103
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]104<p>Note that the C front-end uses LLVM, but does not depend on llvm-gcc. If you
105encounter problems with building Clang, make sure you have the latest SVN
106version of LLVM. LLVM contains support libraries for Clang that will be updated
107as well as development on Clang progresses.</p>
Ted Kremenek675a9ba2008-02-08 07:32:26 +0000[diff] [blame]108
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]109<h3>Simultaneously Building Clang and LLVM:</h3>
Eric Christopher562b4f32008-02-08 07:10:48 +0000[diff] [blame]110
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]111<p>Once you have checked out Clang into the llvm source tree it will build along
112with the rest of <tt>llvm</tt>. To build all of LLVM and Clang together all at
113once simply run <tt>make</tt> from the root LLVM directory.</p>
114
115<p><em>Note:</em> Observe that Clang is technically part of a separate
116Subversion repository. As mentioned above, the latest Clang sources are tied to
117the latest sources in the LLVM tree. You can update your toplevel LLVM project
118and all (possibly unrelated) projects inside it with <tt><b>make
119update</b></tt>. This will run <tt>svn update</tt> on all subdirectories related
120to subversion. </p>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]121
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]122<h3 id="buildWindows">Using Visual Studio</h3>
123
124<p>The following details setting up for and building Clang on Windows using
125Visual Studio:</p>
126
127<ol>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]128 <li>Get the required tools:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]129 <ul>
130 <li><b>Subversion</b>. Source code control program. Get it from:
131 <a href="http://subversion.tigris.org/getting.html">
132 http://subversion.tigris.org/getting.html</a></li>
133 <li><b>cmake</b>. This is used for generating Visual Studio solution and
134 project files. Get it from:
135 <a href="http://www.cmake.org/cmake/resources/software.html">
136 http://www.cmake.org/cmake/resources/software.html</a></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]137 <li><b>Visual Studio 2008 or 2010</b></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]138 <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]139 (which is essential, if you will be developing for clang).
140 Get it from:
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]141 <a href="http://www.python.org/download/">
142 http://www.python.org/download/</a></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]143 <li><b>GnuWin32 tools</b>
144 These are also necessary for running the tests.
145 (Note that the grep from MSYS or Cygwin doesn't work with the tests
146 because of embedded double-quotes in the search strings. The GNU
147 grep does work in this case.)
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]148 Get them from <a href="http://getgnuwin32.sourceforge.net/">
149 http://getgnuwin32.sourceforge.net/</a>.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]150 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]151 </li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]152
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]153 <li>Checkout LLVM:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]154 <ul>
155 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
156 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]157 </li>
158 <li>Checkout Clang:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]159 <ul>
160 <li><tt>cd llvm\tools</tt>
161 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
162 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]163 </li>
164 <li>Run cmake to generate the Visual Studio solution and project files:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]165 <ul>
Michael J. Spencer0de57862010-12-16 22:01:14 +0000[diff] [blame]166 <li><tt>cd ..\..</tt> (back to where you started)</li>
167 <li><tt>mkdir build</tt> (for building without polluting the source dir)</li>
168 <li><tt>cd build</tt></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]169 <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]170 <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]171 <li>By default, cmake will target LLVM to X86. If you want all targets
172 (needed if you want to run the LLVM tests), add the <tt>-DLLVM_TARGETS_TO_BUILD=all</tt> option to the
173 cmake command line. Or specify a target from the LLVM_TARGETS_TO_BUILD
174 definition in CMakeLists.txt.</li>
175 <li>See the <a href="http://www.llvm.org/docs/CMake.html">LLVM CMake guide</a> for
176 more information on other configuration options for cmake.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]177 <li>The above, if successful, will have created an LLVM.sln file in the
NAKAMURA Takumi542c7622011-07-25 12:40:26 +0000[diff] [blame]178 <tt>build</tt> directory.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]179 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]180 </li>
181 <li>Build Clang:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]182 <ul>
183 <li>Open LLVM.sln in Visual Studio.</li>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]184 <li>Build the "clang" project for just the compiler driver and front end, or
185 the "ALL_BUILD" project to build everything, including tools.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]186 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]187 </li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]188 <li>Try it out (assuming you added llvm/debug/bin to your path). (See the
189 running examples from above.)</li>
190 <li>See <a href="hacking.html#testingWindows">
191 Hacking on clang - Testing using Visual Studio on Windows</a> for information
192 on running regression tests on Windows.</li>
193</ol>
194
195<p>Note that once you have checked out both llvm and clang, to synchronize
196to the latest code base, use the <tt>svn update</tt> command in both the
197llvm and llvm\tools\clang directories, as they are separate repositories.</p>
198
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]199<h2 id="driver">Clang Compiler Driver (Drop-in Substitute for GCC)</h2>
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]200
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]201<p>The <tt>clang</tt> tool is the compiler driver and front-end, which is
202designed to be a drop-in replacement for the <tt>gcc</tt> command. Here are
203some examples of how to use the high-level driver:
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]204</p>
205
206<pre class="code">
207$ <b>cat t.c</b>
208#include &lt;stdio.h&gt;
209int main(int argc, char **argv) { printf("hello world\n"); }
210$ <b>clang t.c</b>
211$ <b>./a.out</b>
212hello world
213</pre>
214
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]215<p>The 'clang' driver is designed to work as closely to GCC as possible to
216 maximize portability. The only major difference between the two is that
217 Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see
Chris Lattnerd73fef62009-11-09 04:04:07 +0000[diff] [blame]218 weird link-time errors relating to inline functions, try passing -std=gnu89
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]219 to clang.</p>
220
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]221<h2>Examples of using Clang</h2>
222
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]223<!-- Thanks to
224 http://shiflett.org/blog/2006/oct/formatting-and-highlighting-php-code-listings
225Site suggested using pre in CSS, but doesn't work in IE, so went for the <pre>
226tag. -->
227
228<pre class="code">
229$ <b>cat ~/t.c</b>
230typedef float V __attribute__((vector_size(16)));
231V foo(V a, V b) { return a+b*a; }
232</pre>
233
234
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]235<h3>Preprocessing:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]236
237<pre class="code">
238$ <b>clang ~/t.c -E</b>
239# 1 "/Users/sabre/t.c" 1
240
241typedef float V __attribute__((vector_size(16)));
242
243V foo(V a, V b) { return a+b*a; }
244</pre>
245
246
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]247<h3>Type checking:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]248
249<pre class="code">
250$ <b>clang -fsyntax-only ~/t.c</b>
251</pre>
252
253
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]254<h3>GCC options:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]255
256<pre class="code">
257$ <b>clang -fsyntax-only ~/t.c -pedantic</b>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]258/Users/sabre/t.c:2:17: <span style="color:magenta">warning:</span> extension used
259<span style="color:darkgreen">typedef float V __attribute__((vector_size(16)));</span>
260<span style="color:blue"> ^</span>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]2611 diagnostic generated.
262</pre>
263
264
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]265<h3>Pretty printing from the AST:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]266
Sylvestre Ledrubed28ac2012-07-23 08:59:39 +0000[diff] [blame^]267<p>Note, the <tt>-cc1</tt> argument indicates the compiler front-end, and
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]268not the driver, should be run. The compiler front-end has several additional
269Clang specific features which are not exposed through the GCC compatible driver
270interface.</p>
271
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]272<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]273$ <b>clang -cc1 ~/t.c -ast-print</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]274typedef float V __attribute__(( vector_size(16) ));
275V foo(V a, V b) {
276 return a + b * a;
277}
278</pre>
279
280
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]281<h3>Code generation with LLVM:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]282
283<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]284$ <b>clang ~/t.c -S -emit-llvm -o -</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]285define &lt;4 x float&gt; @foo(&lt;4 x float&gt; %a, &lt;4 x float&gt; %b) {
286entry:
287 %mul = mul &lt;4 x float&gt; %b, %a
288 %add = add &lt;4 x float&gt; %mul, %a
289 ret &lt;4 x float&gt; %add
290}
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]291$ <b>clang -fomit-frame-pointer -O3 -S -o - t.c</b> <i># On x86_64</i>
292...
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]293_foo:
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]294Leh_func_begin1:
295 mulps %xmm0, %xmm1
296 addps %xmm1, %xmm0
297 ret
298Leh_func_end1:
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]299</pre>
300
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]301</div>
302</body>
303</html>