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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
86 to find your C++ standard library headers. If Clang cannot find your
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]87 system libstdc++ headers, please follow these instructions:
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]88 <ul>
Gabor Greif74350822010-03-29 21:36:06 +0000[diff] [blame]89 <li>'<tt>gcc -v -x c++ /dev/null -fsyntax-only</tt>' to get the
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]90 path.</li>
91 <li>Look for the comment "FIXME: temporary hack:
Chris Lattnerca8c49f2009-03-10 16:01:44 +0000[diff] [blame]92 hard-coded paths" in <tt>clang/lib/Frontend/InitHeaderSearch.cpp</tt> and
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]93 change the lines below to include that path.</li>
94 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]95 </li>
96 <li>Try it out (assuming you add llvm/Debug+Asserts/bin to your path):
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]97 <ul>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]98 <li><tt>clang --help</tt></li>
99 <li><tt>clang file.c -fsyntax-only</tt> (check for correctness)</li>
100 <li><tt>clang file.c -S -emit-llvm -o -</tt> (print out unoptimized llvm code)</li>
101 <li><tt>clang file.c -S -emit-llvm -o - -O3</tt></li>
102 <li><tt>clang file.c -S -O3 -o -</tt> (output native machine code)</li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]103 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]104 </li>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]105</ol>
106
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]107<p>Note that the C front-end uses LLVM, but does not depend on llvm-gcc. If you
108encounter problems with building Clang, make sure you have the latest SVN
109version of LLVM. LLVM contains support libraries for Clang that will be updated
110as well as development on Clang progresses.</p>
Ted Kremenek675a9ba2008-02-08 07:32:26 +0000[diff] [blame]111
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]112<h3>Simultaneously Building Clang and LLVM:</h3>
Eric Christopher562b4f32008-02-08 07:10:48 +0000[diff] [blame]113
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]114<p>Once you have checked out Clang into the llvm source tree it will build along
115with the rest of <tt>llvm</tt>. To build all of LLVM and Clang together all at
116once simply run <tt>make</tt> from the root LLVM directory.</p>
117
118<p><em>Note:</em> Observe that Clang is technically part of a separate
119Subversion repository. As mentioned above, the latest Clang sources are tied to
120the latest sources in the LLVM tree. You can update your toplevel LLVM project
121and all (possibly unrelated) projects inside it with <tt><b>make
122update</b></tt>. This will run <tt>svn update</tt> on all subdirectories related
123to subversion. </p>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]124
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]125<h3 id="buildWindows">Using Visual Studio</h3>
126
127<p>The following details setting up for and building Clang on Windows using
128Visual Studio:</p>
129
130<ol>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]131 <li>Get the required tools:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]132 <ul>
133 <li><b>Subversion</b>. Source code control program. Get it from:
134 <a href="http://subversion.tigris.org/getting.html">
135 http://subversion.tigris.org/getting.html</a></li>
136 <li><b>cmake</b>. This is used for generating Visual Studio solution and
137 project files. Get it from:
138 <a href="http://www.cmake.org/cmake/resources/software.html">
139 http://www.cmake.org/cmake/resources/software.html</a></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]140 <li><b>Visual Studio 2008 or 2010</b></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]141 <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]142 (which is essential, if you will be developing for clang).
143 Get it from:
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]144 <a href="http://www.python.org/download/">
145 http://www.python.org/download/</a></li>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]146 <li><b>GnuWin32 tools</b>
147 These are also necessary for running the tests.
148 (Note that the grep from MSYS or Cygwin doesn't work with the tests
149 because of embedded double-quotes in the search strings. The GNU
150 grep does work in this case.)
NAKAMURA Takumicc8770a2011-03-27 02:04:21 +0000[diff] [blame]151 Get them from <a href="http://getgnuwin32.sourceforge.net/">
152 http://getgnuwin32.sourceforge.net/</a>.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]153 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]154 </li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]155
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]156 <li>Checkout LLVM:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]157 <ul>
158 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
159 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]160 </li>
161 <li>Checkout Clang:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]162 <ul>
163 <li><tt>cd llvm\tools</tt>
164 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li>
165 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]166 </li>
167 <li>Run cmake to generate the Visual Studio solution and project files:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]168 <ul>
Michael J. Spencer0de57862010-12-16 22:01:14 +0000[diff] [blame]169 <li><tt>cd ..\..</tt> (back to where you started)</li>
170 <li><tt>mkdir build</tt> (for building without polluting the source dir)</li>
171 <li><tt>cd build</tt></li>
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]172 <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]173 <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]174 <li>By default, cmake will target LLVM to X86. If you want all targets
175 (needed if you want to run the LLVM tests), add the <tt>-DLLVM_TARGETS_TO_BUILD=all</tt> option to the
176 cmake command line. Or specify a target from the LLVM_TARGETS_TO_BUILD
177 definition in CMakeLists.txt.</li>
178 <li>See the <a href="http://www.llvm.org/docs/CMake.html">LLVM CMake guide</a> for
179 more information on other configuration options for cmake.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]180 <li>The above, if successful, will have created an LLVM.sln file in the
NAKAMURA Takumi542c7622011-07-25 12:40:26 +0000[diff] [blame]181 <tt>build</tt> directory.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]182 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]183 </li>
184 <li>Build Clang:
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]185 <ul>
186 <li>Open LLVM.sln in Visual Studio.</li>
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]187 <li>Build the "clang" project for just the compiler driver and front end, or
188 the "ALL_BUILD" project to build everything, including tools.</li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]189 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]190 </li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]191 <li>Try it out (assuming you added llvm/debug/bin to your path). (See the
192 running examples from above.)</li>
193 <li>See <a href="hacking.html#testingWindows">
194 Hacking on clang - Testing using Visual Studio on Windows</a> for information
195 on running regression tests on Windows.</li>
196</ol>
197
198<p>Note that once you have checked out both llvm and clang, to synchronize
199to the latest code base, use the <tt>svn update</tt> command in both the
200llvm and llvm\tools\clang directories, as they are separate repositories.</p>
201
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]202<h2 id="driver">Clang Compiler Driver (Drop-in Substitute for GCC)</h2>
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]203
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]204<p>The <tt>clang</tt> tool is the compiler driver and front-end, which is
205designed to be a drop-in replacement for the <tt>gcc</tt> command. Here are
206some examples of how to use the high-level driver:
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]207</p>
208
209<pre class="code">
210$ <b>cat t.c</b>
211#include &lt;stdio.h&gt;
212int main(int argc, char **argv) { printf("hello world\n"); }
213$ <b>clang t.c</b>
214$ <b>./a.out</b>
215hello world
216</pre>
217
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]218<p>The 'clang' driver is designed to work as closely to GCC as possible to
219 maximize portability. The only major difference between the two is that
220 Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see
Chris Lattnerd73fef62009-11-09 04:04:07 +0000[diff] [blame]221 weird link-time errors relating to inline functions, try passing -std=gnu89
Chris Lattner63d423d2009-11-09 03:21:02 +0000[diff] [blame]222 to clang.</p>
223
Ted Kremenek9b16da32009-03-27 16:32:57 +0000[diff] [blame]224<h2>Examples of using Clang</h2>
225
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]226<!-- Thanks to
227 http://shiflett.org/blog/2006/oct/formatting-and-highlighting-php-code-listings
228Site suggested using pre in CSS, but doesn't work in IE, so went for the <pre>
229tag. -->
230
231<pre class="code">
232$ <b>cat ~/t.c</b>
233typedef float V __attribute__((vector_size(16)));
234V foo(V a, V b) { return a+b*a; }
235</pre>
236
237
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]238<h3>Preprocessing:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]239
240<pre class="code">
241$ <b>clang ~/t.c -E</b>
242# 1 "/Users/sabre/t.c" 1
243
244typedef float V __attribute__((vector_size(16)));
245
246V foo(V a, V b) { return a+b*a; }
247</pre>
248
249
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]250<h3>Type checking:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]251
252<pre class="code">
253$ <b>clang -fsyntax-only ~/t.c</b>
254</pre>
255
256
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]257<h3>GCC options:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]258
259<pre class="code">
260$ <b>clang -fsyntax-only ~/t.c -pedantic</b>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]261/Users/sabre/t.c:2:17: <span style="color:magenta">warning:</span> extension used
262<span style="color:darkgreen">typedef float V __attribute__((vector_size(16)));</span>
263<span style="color:blue"> ^</span>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]2641 diagnostic generated.
265</pre>
266
267
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]268<h3>Pretty printing from the AST:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]269
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]270<p>Note, the <tt>-cc1</tt> argument indicates the the compiler front-end, and
271not the driver, should be run. The compiler front-end has several additional
272Clang specific features which are not exposed through the GCC compatible driver
273interface.</p>
274
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]275<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]276$ <b>clang -cc1 ~/t.c -ast-print</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]277typedef float V __attribute__(( vector_size(16) ));
278V foo(V a, V b) {
279 return a + b * a;
280}
281</pre>
282
283
Ted Kremenek35f29c52008-06-17 13:48:36 +0000[diff] [blame]284<h3>Code generation with LLVM:</h3>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]285
286<pre class="code">
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]287$ <b>clang ~/t.c -S -emit-llvm -o -</b>
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]288define &lt;4 x float&gt; @foo(&lt;4 x float&gt; %a, &lt;4 x float&gt; %b) {
289entry:
290 %mul = mul &lt;4 x float&gt; %b, %a
291 %add = add &lt;4 x float&gt; %mul, %a
292 ret &lt;4 x float&gt; %add
293}
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]294$ <b>clang -fomit-frame-pointer -O3 -S -o - t.c</b> <i># On x86_64</i>
295...
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]296_foo:
Daniel Dunbardd63b282009-12-11 23:04:35 +0000[diff] [blame]297Leh_func_begin1:
298 mulps %xmm0, %xmm1
299 addps %xmm1, %xmm0
300 ret
301Leh_func_end1:
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]302</pre>
303
Eric Christopher7dc0e572008-02-08 06:45:49 +0000[diff] [blame]304</div>
305</body>
306</html>