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7 <title>Building the LLVM GCC Front-End</title>
8</head>
9<body>
10
11<div class="doc_title">
12 Building the LLVM GCC Front-End
13</div>
14
15<ol>
16 <li><a href="#instructions">Building llvm-gcc from Source</a></li>
17 <li><a href="#license">License Information</a></li>
18</ol>
19
20<div class="doc_author">
21 <p>Written by the LLVM Team</p>
22</div>
23
24<!-- *********************************************************************** -->
25<div class="doc_section">
26 <a name="instructions">Building llvm-gcc from Source</a>
27</div>
28<!-- *********************************************************************** -->
29
30<div class="doc_text">
31
32<p>This section describes how to acquire and build llvm-gcc 4.0 and 4.2, which are
33based on the GCC 4.0.1/4.2.1 front-ends respectively. Both front-ends support C,
34C++, Objective-C and Objective-C++. The 4.2 front-end also supports Ada and
35Fortran to some extent. Note that the instructions for building these front-ends
36are completely different (and much easier!) than those for building llvm-gcc3 in
37the past.</p>
38
39<ol>
40 <li><p>Retrieve the appropriate llvm-gcc4.x-y.z.source.tar.gz archive from the
41 <a href="http://llvm.org/releases/">llvm web site</a>.</p>
42
43 <p>It is also possible to download the sources of the llvm-gcc front end
44 from a read-only mirror using subversion. To check out the 4.0 code
45 for first time use:</p>
46
47<div class="doc_code">
48<pre>
49svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.0/trunk <i>dst-directory</i>
50</pre>
51</div>
52
53<p>To check out the 4.2 code use:</p>
54
55<div class="doc_code">
56<pre>
57svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk <i>dst-directory</i>
58</pre>
59</div>
60
61 <p>After that, the code can be be updated in the destination directory
62 using:</p>
63
64<div class="doc_code">
65<pre>svn update</pre>
66</div>
67
68 <p>The mirror is brought up to date every evening.</p></li>
69
70 <li>Follow the directions in the top-level <tt>README.LLVM</tt> file for
71 up-to-date instructions on how to build llvm-gcc. See below for building
72 with support for Ada or Fortran.
73</ol>
74
75</div>
76
77<!-- *********************************************************************** -->
78<div class="doc_section">
79 <a name="license">Building the Ada front-end</a>
80</div>
81
82<div class="doc_text">
83<p>Building with support for Ada amounts to following the directions in the
84top-level <tt>README.LLVM</tt> file, adding ",ada" to EXTRALANGS, for example:
85<tt>EXTRALANGS=,ada</tt></p>
86
87<p>There are some complications however:</p>
88
89<ol>
90 <li><p>The only platform for which the Ada front-end is known to build is
91 32 bit intel x86 running linux. It is unlikely to build for other
92 systems without some work.</p></li>
93 <li><p>The build requires having a compiler that supports Ada, C and C++.
94 The Ada front-end is written in Ada so an Ada compiler is needed to
95 build it. What is more, the Ada compiler must not be more recent
96 than what it is trying to compile, otherwise the build will fail.
97 This rules out gcc-4.3 (but not gcc-4.2) and also the
98 <a href="http://libre.adacore.com/">2007 GNAT GPL Edition</a>.
99 The LLVM parts of llvm-gcc are written in C++ so a C++
100 compiler is needed to build them. The rest of gcc is written in C.
101 Some linux distributions provide a version of gcc that supports all
102 three languages (the Ada part often comes as an add-on package to
103 the rest of gcc). Otherwise it is possible to combine two versions
104 of gcc, one that supports Ada and C (such as the
105 <a href="http://libre.adacore.com/">2006 GNAT GPL Edition</a>)
106 and another which supports C++, see below.</p></li>
107 <li><p>Because the Ada front-end is experimental, it is wise to build the
108 compiler with checking enabled. This causes it to run slower, but
109 helps catch mistakes in the compiler (please report any problems using
110 <a href="http://llvm.org/bugs">LLVM bugzilla</a>).</p></li>
111</ol>
112
113<p>Supposing appropriate compilers are available, llvm-gcc with Ada support can
114 be built on an x86-32 linux box using the following recipe:</p>
115
116<ol>
117 <li><p>Download the <a href="http://llvm.org/releases/download.html">LLVM source</a>
118 and unpack it:</p>
119
120<div class="doc_code">
121<pre>wget http://llvm.org/releases/2.2/llvm-2.2.tar.gz
122tar xzf llvm-2.2.tar.gz
123mv llvm-2.2 llvm</pre>
124</div>
125
126 <p>or <a href="GettingStarted.html#checkout">check out the
127 latest version from subversion</a>:</p>
128
129<div class="doc_code">
130<pre>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</pre>
131</div>
132 </li>
133
134 <li><p>Download the
135 <a href="http://llvm.org/releases/download.html">llvm-gcc-4.2 source</a>
136 and unpack it:</p>
137
138<div class="doc_code">
139<pre>wget http://llvm.org/releases/2.2/llvm-gcc4.2-2.2.source.tar.gz
140tar xzf llvm-gcc4.2-2.2.source.tar.gz
141mv llvm-gcc4.2-2.2.source llvm-gcc-4.2</pre>
142</div>
143
144 <p>or <a href="GettingStarted.html#checkout">check out the
145 latest version from subversion</a>:</p>
146
147<div class="doc_code">
148<pre>svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk llvm-gcc-4.2</pre>
149</div>
150 </li>
151
152 <li><p>Make a build directory <tt>llvm-objects</tt> for llvm and make it the
153 current directory:</p>
154
155<div class="doc_code">
156<pre>mkdir llvm-objects
157cd llvm-objects</pre>
158</div>
159 </li>
160
161 <li><p>Configure LLVM (here it is configured to install into <tt>/usr/local</tt>):</p>
162
163<div class="doc_code">
164<pre>../llvm/configure --prefix=<b>/usr/local</b></pre>
165</div>
166
167 <p>If you have a multi-compiler setup and the C++ compiler is not the
168 default, then you can configure like this:</p>
169
170<div class="doc_code">
171<pre>CXX=<b>PATH_TO_C++_COMPILER</b> ../llvm/configure --prefix=<b>/usr/local</b></pre>
172</div>
173 </li>
174
175 <li><p>Build LLVM with checking enabled (use <tt>ENABLE_OPTIMIZED=1</tt> to
176 build without checking):</p>
177
178<div class="doc_code">
179<pre>make ENABLE_OPTIMIZED=0</pre>
180</div>
181 </li>
182
183 <li><p>Install LLVM (optional):</p>
184
185<div class="doc_code">
186<pre>make install</pre>
187</div>
188 </li>
189
190 <li><p>Make a build directory <tt>llvm-gcc-4.2-objects</tt> for llvm-gcc and make it the
191 current directory:</p>
192
193<div class="doc_code">
194<pre>
195cd ..
196mkdir llvm-gcc-4.2-objects
197cd llvm-gcc-4.2-objects</pre>
198</div>
199 </li>
200
201 <li><p>Configure llvm-gcc (here it is configured to install into <tt>/usr/local</tt>).
202 The <tt>--enable-checking</tt> flag turns on sanity checks inside the compiler.
203 If you omit it then LLVM must be built with <tt>make ENABLE_OPTIMIZED=1</tt>.
204 Additional languages can be appended to the --enable-languages switch,
205 for example <tt>--enable-languages=ada,c,c++</tt>.</p>
206
207<div class="doc_code">
208<pre>../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-shared --disable-bootstrap --disable-multilib</pre>
209</div>
210
211 <p>If you have a multi-compiler setup, then you can configure like this:</p>
212<div class="doc_code">
213
214<pre>
215export CC=<b>PATH_TO_C_AND_ADA_COMPILER</b>
216export CXX=<b>PATH_TO_C++_COMPILER</b>
217../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-shared --disable-bootstrap --disable-multilib</pre>
218</div>
219 </li>
220
221 <li><p>Build and install the compiler:</p>
222
223<div class="doc_code">
224<pre>make
225make install</pre>
226</div>
227 </li>
228</ol>
229
230</div>
231
232<!-- *********************************************************************** -->
233<div class="doc_section">
234 <a name="license">Building the Fortran front-end</a>
235</div>
236
237<div class="doc_text">
238<p>
239To build with support for Fortran, follow the directions in the top-level
240<tt>README.LLVM</tt> file, adding ",fortran" to EXTRALANGS, for example:</p>
241
242<div class="doc_code">
243<pre>
244EXTRALANGS=,fortran
245</pre>
246</div>
247
248</div>
249
250<!-- *********************************************************************** -->
251<div class="doc_section">
252 <a name="license">License Information</a>
253</div>
254
255<div class="doc_text">
256<p>
257The LLVM GCC frontend is licensed to you under the GNU General Public License
258and the GNU Lesser General Public License. Please see the files COPYING and
259COPYING.LIB for more details.
260</p>
261
262<p>
263More information is <a href="FAQ.html#license">available in the FAQ</a>.
264</p>
265</div>
266
267<!-- *********************************************************************** -->
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