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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 4.2, which is based
33 on the GCC 4.2.1 front-end. Supported languages are Ada, C, C++, Fortran,
34 Objective-C and Objective-C++. Note that the instructions for building these
35 front-ends are completely different (and much easier!) than those for building
36 llvm-gcc3 in the past.</p>
39 <li><p>Retrieve the appropriate llvm-gcc-4.2-x.y.source.tar.gz archive from the
40 <a href="http://llvm.org/releases/">llvm web site</a>.</p>
42 <p>It is also possible to download the sources of the llvm-gcc front end
43 from a read-only mirror using subversion. To check out the 4.2 code
44 for first time use:</p>
46 <div class="doc_code">
48 svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk <i>dst-directory</i>
52 <p>After that, the code can be be updated in the destination directory
55 <div class="doc_code">
59 <p>The mirror is brought up to date every evening.</p></li>
61 <li>Follow the directions in the top-level <tt>README.LLVM</tt> file for
62 up-to-date instructions on how to build llvm-gcc. See below for building
63 with support for Ada or Fortran.
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69 <div class="doc_section">
70 <a name="license">Building the Ada front-end</a>
73 <div class="doc_text">
74 <p>Building with support for Ada amounts to following the directions in the
75 top-level <tt>README.LLVM</tt> file, adding ",ada" to EXTRALANGS, for example:
76 <tt>EXTRALANGS=,ada</tt></p>
78 <p>There are some complications however:</p>
81 <li><p>The only platform for which the Ada front-end is known to build is
82 32 bit intel x86 running linux. It is unlikely to build for other
83 systems without some work.</p></li>
84 <li><p>The build requires having a compiler that supports Ada, C and C++.
85 The Ada front-end is written in Ada so an Ada compiler is needed to
86 build it. Compilers known to work with the
87 <a href="http://llvm.org/releases/download.html">LLVM 2.3 release</a>
88 are <a href="http://gcc.gnu.org/releases.html">gcc-4.2</a> and the
89 2005, 2006 and 2007 versions of the
90 <a href="http://libre.adacore.com/">GNAT GPL Edition</a>.
91 The LLVM parts of llvm-gcc are written in C++ so a C++ compiler is
92 needed to build them. The rest of gcc is written in C.
93 Some linux distributions provide a version of gcc that supports all
94 three languages (the Ada part often comes as an add-on package to
95 the rest of gcc). Otherwise it is possible to combine two versions
96 of gcc, one that supports Ada and C (such as the
97 <a href="http://libre.adacore.com/">2007 GNAT GPL Edition</a>)
98 and another which supports C++, see below.</p></li>
99 <li><p>Because the Ada front-end is experimental, it is wise to build the
100 compiler with checking enabled. This causes it to run much slower, but
101 helps catch mistakes in the compiler (please report any problems using
102 <a href="http://llvm.org/bugs">LLVM bugzilla</a>).</p></li>
105 <p>Supposing appropriate compilers are available, llvm-gcc with Ada support can
106 be built on an x86-32 linux box using the following recipe:</p>
109 <li><p>Download the <a href="http://llvm.org/releases/download.html">LLVM source</a>
112 <div class="doc_code">
113 <pre>wget http://llvm.org/releases/2.3/llvm-2.3.tar.gz
114 tar xzf llvm-2.3.tar.gz
115 mv llvm-2.3 llvm</pre>
118 <p>or <a href="GettingStarted.html#checkout">check out the
119 latest version from subversion</a>:</p>
121 <div class="doc_code">
122 <pre>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</pre>
127 <a href="http://llvm.org/releases/download.html">llvm-gcc-4.2 source</a>
130 <div class="doc_code">
131 <pre>wget http://llvm.org/releases/2.3/llvm-gcc-4.2-2.3.source.tar.gz
132 tar xzf llvm-gcc-4.2-2.3.source.tar.gz
133 mv llvm-gcc4.2-2.3.source llvm-gcc-4.2</pre>
136 <p>or <a href="GettingStarted.html#checkout">check out the
137 latest version from subversion</a>:</p>
139 <div class="doc_code">
140 <pre>svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk llvm-gcc-4.2</pre>
144 <li><p>Make a build directory <tt>llvm-objects</tt> for llvm and make it the
145 current directory:</p>
147 <div class="doc_code">
148 <pre>mkdir llvm-objects
149 cd llvm-objects</pre>
153 <li><p>Configure LLVM (here it is configured to install into <tt>/usr/local</tt>):</p>
155 <div class="doc_code">
156 <pre>../llvm/configure --prefix=<b>/usr/local</b></pre>
159 <p>If you have a multi-compiler setup and the C++ compiler is not the
160 default, then you can configure like this:</p>
162 <div class="doc_code">
163 <pre>CXX=<b>PATH_TO_C++_COMPILER</b> ../llvm/configure --prefix=<b>/usr/local</b></pre>
167 <li><p>Build LLVM with checking enabled (use <tt>ENABLE_OPTIMIZED=1</tt> to
168 build without checking):</p>
170 <div class="doc_code">
171 <pre>make ENABLE_OPTIMIZED=0</pre>
175 <li><p>Install LLVM (optional):</p>
177 <div class="doc_code">
178 <pre>make ENABLE_OPTIMIZED=0 install</pre>
182 <li><p>Make a build directory <tt>llvm-gcc-4.2-objects</tt> for llvm-gcc and make it the
183 current directory:</p>
185 <div class="doc_code">
188 mkdir llvm-gcc-4.2-objects
189 cd llvm-gcc-4.2-objects</pre>
193 <li><p>Configure llvm-gcc (here it is configured to install into <tt>/usr/local</tt>).
194 The <tt>--enable-checking</tt> flag turns on sanity checks inside the compiler.
195 If you omit it then LLVM should be built with <tt>make ENABLE_OPTIMIZED=1</tt>.
196 Additional languages can be appended to the --enable-languages switch,
197 for example <tt>--enable-languages=ada,c,c++</tt>.</p>
199 <div class="doc_code">
200 <pre>../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-bootstrap --disable-multilib</pre>
203 <p>If you have a multi-compiler setup, then you can configure like this:</p>
204 <div class="doc_code">
207 export CC=<b>PATH_TO_C_AND_ADA_COMPILER</b>
208 export CXX=<b>PATH_TO_C++_COMPILER</b>
209 ../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c --enable-checking --enable-llvm=$PWD/../llvm-objects --disable-bootstrap --disable-multilib</pre>
213 <li><p>Build and install the compiler:</p>
215 <div class="doc_code">
224 <!-- *********************************************************************** -->
225 <div class="doc_section">
226 <a name="license">Building the Fortran front-end</a>
229 <div class="doc_text">
231 To build with support for Fortran, follow the directions in the top-level
232 <tt>README.LLVM</tt> file, adding ",fortran" to EXTRALANGS, for example:</p>
234 <div class="doc_code">
242 <!-- *********************************************************************** -->
243 <div class="doc_section">
244 <a name="license">License Information</a>
247 <div class="doc_text">
249 The LLVM GCC frontend is licensed to you under the GNU General Public License
250 and the GNU Lesser General Public License. Please see the files COPYING and
251 COPYING.LIB for more details.
255 More information is <a href="FAQ.html#license">available in the FAQ</a>.
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