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7 <title>Building the LLVM GCC Front-End</title>
11 <div class="doc_title">
12 Building the LLVM GCC Front-End
16 <li><a href="#instructions">Building llvm-gcc from Source</a></li>
17 <li><a href="#license">License Information</a></li>
20 <div class="doc_author">
21 <p>Written by the LLVM Team</p>
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25 <div class="doc_section">
26 <a name="instructions">Building llvm-gcc from Source</a>
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30 <div class="doc_text">
32 <p>This section describes how to acquire and build llvm-gcc 4.0 and 4.2, which are
33 based on the GCC 4.0.1/4.2.1 front-ends respectively. Both front-ends support C,
34 C++, Objective-C and Objective-C++. The 4.2 front-end also supports Ada and
35 Fortran to some extent. Note that the instructions for building these front-ends
36 are completely different (and much easier!) than those for building llvm-gcc3 in
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>
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>
47 <div class="doc_code">
49 svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.0/trunk <i>dst-directory</i>
53 <p>To check out the 4.2 code use:</p>
55 <div class="doc_code">
57 svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk <i>dst-directory</i>
61 <p>After that, the code can be be updated in the destination directory
64 <div class="doc_code">
68 <p>The mirror is brought up to date every evening.</p></li>
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.
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78 <div class="doc_section">
79 <a name="license">Building the Ada front-end</a>
82 <div class="doc_text">
83 <p>Building with support for Ada amounts to following the directions in the
84 top-level <tt>README.LLVM</tt> file, adding ",ada" to EXTRALANGS, for example:
85 <tt>EXTRALANGS=,ada</tt></p>
87 <p>There are some complications however:</p>
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. Compilers known to work with the
96 <a href="http://llvm.org/releases/download.html">LLVM 2.2 release</a>
97 are <a href="http://gcc.gnu.org/releases.html">gcc-4.2</a> and the
98 <a href="http://libre.adacore.com/">2005 GNAT GPL Edition</a>.
99 <a href="GettingStarted.html#checkout">LLVM from subversion</a>
101 <a href="http://libre.adacore.com/">2006 and 2007 GNAT GPL Editions</a>.
102 The LLVM parts of llvm-gcc are written in C++ so a C++ compiler is
103 needed to build them. The rest of gcc is written in C.
104 Some linux distributions provide a version of gcc that supports all
105 three languages (the Ada part often comes as an add-on package to
106 the rest of gcc). Otherwise it is possible to combine two versions
107 of gcc, one that supports Ada and C (such as the
108 <a href="http://libre.adacore.com/">2005 GNAT GPL Edition</a>)
109 and another which supports C++, see below.</p></li>
110 <li><p>Because the Ada front-end is experimental, it is wise to build the
111 compiler with checking enabled. This causes it to run much slower, but
112 helps catch mistakes in the compiler (please report any problems using
113 <a href="http://llvm.org/bugs">LLVM bugzilla</a>).</p></li>
116 <p>Supposing appropriate compilers are available, llvm-gcc with Ada support can
117 be built on an x86-32 linux box using the following recipe:</p>
120 <li><p>Download the <a href="http://llvm.org/releases/download.html">LLVM source</a>
123 <div class="doc_code">
124 <pre>wget http://llvm.org/releases/2.2/llvm-2.2.tar.gz
125 tar xzf llvm-2.2.tar.gz
126 mv llvm-2.2 llvm</pre>
129 <p>or <a href="GettingStarted.html#checkout">check out the
130 latest version from subversion</a>:</p>
132 <div class="doc_code">
133 <pre>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</pre>
138 <a href="http://llvm.org/releases/download.html">llvm-gcc-4.2 source</a>
141 <div class="doc_code">
142 <pre>wget http://llvm.org/releases/2.2/llvm-gcc4.2-2.2.source.tar.gz
143 tar xzf llvm-gcc4.2-2.2.source.tar.gz
144 mv llvm-gcc4.2-2.2.source llvm-gcc-4.2</pre>
147 <p>or <a href="GettingStarted.html#checkout">check out the
148 latest version from subversion</a>:</p>
150 <div class="doc_code">
151 <pre>svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk llvm-gcc-4.2</pre>
155 <li><p>Make a build directory <tt>llvm-objects</tt> for llvm and make it the
156 current directory:</p>
158 <div class="doc_code">
159 <pre>mkdir llvm-objects
160 cd llvm-objects</pre>
164 <li><p>Configure LLVM (here it is configured to install into <tt>/usr/local</tt>):</p>
166 <div class="doc_code">
167 <pre>../llvm/configure --prefix=<b>/usr/local</b></pre>
170 <p>If you have a multi-compiler setup and the C++ compiler is not the
171 default, then you can configure like this:</p>
173 <div class="doc_code">
174 <pre>CXX=<b>PATH_TO_C++_COMPILER</b> ../llvm/configure --prefix=<b>/usr/local</b></pre>
178 <li><p>Build LLVM with checking enabled (use <tt>ENABLE_OPTIMIZED=1</tt> to
179 build without checking):</p>
181 <div class="doc_code">
182 <pre>make ENABLE_OPTIMIZED=0</pre>
186 <li><p>Install LLVM (optional):</p>
188 <div class="doc_code">
189 <pre>make install</pre>
193 <li><p>Make a build directory <tt>llvm-gcc-4.2-objects</tt> for llvm-gcc and make it the
194 current directory:</p>
196 <div class="doc_code">
199 mkdir llvm-gcc-4.2-objects
200 cd llvm-gcc-4.2-objects</pre>
204 <li><p>Configure llvm-gcc (here it is configured to install into <tt>/usr/local</tt>).
205 The <tt>--enable-checking</tt> flag turns on sanity checks inside the compiler.
206 If you omit it then LLVM must be built with <tt>make ENABLE_OPTIMIZED=1</tt>.
207 Additional languages can be appended to the --enable-languages switch,
208 for example <tt>--enable-languages=ada,c,c++</tt>.</p>
210 <div class="doc_code">
211 <pre>../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-shared --disable-bootstrap --disable-multilib</pre>
214 <p>If you have a multi-compiler setup, then you can configure like this:</p>
215 <div class="doc_code">
218 export CC=<b>PATH_TO_C_AND_ADA_COMPILER</b>
219 export CXX=<b>PATH_TO_C++_COMPILER</b>
220 ../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-shared --disable-bootstrap --disable-multilib</pre>
224 <li><p>Build and install the compiler:</p>
226 <div class="doc_code">
235 <!-- *********************************************************************** -->
236 <div class="doc_section">
237 <a name="license">Building the Fortran front-end</a>
240 <div class="doc_text">
242 To build with support for Fortran, follow the directions in the top-level
243 <tt>README.LLVM</tt> file, adding ",fortran" to EXTRALANGS, for example:</p>
245 <div class="doc_code">
253 <!-- *********************************************************************** -->
254 <div class="doc_section">
255 <a name="license">License Information</a>
258 <div class="doc_text">
260 The LLVM GCC frontend is licensed to you under the GNU General Public License
261 and the GNU Lesser General Public License. Please see the files COPYING and
262 COPYING.LIB for more details.
266 More information is <a href="FAQ.html#license">available in the FAQ</a>.
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