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<h1> | |
Building the LLVM GCC Front-End | |
</h1> | |
<ol> | |
<li><a href="#instructions">Building llvm-gcc from Source</a></li> | |
<li><a href="#ada">Building the Ada front-end</a></li> | |
<li><a href="#fortran">Building the Fortran front-end</a></li> | |
<li><a href="#license">License Information</a></li> | |
</ol> | |
<div class="doc_author"> | |
<p>Written by the LLVM Team</p> | |
</div> | |
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<h2><a name="instructions">Building llvm-gcc from Source</a></h2> | |
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<div> | |
<p>This section describes how to acquire and build llvm-gcc 4.2, which is based | |
on the GCC 4.2.1 front-end. Supported languages are Ada, C, C++, Fortran, | |
Objective-C and Objective-C++. Note that the instructions for building these | |
front-ends are completely different (and much easier!) than those for building | |
llvm-gcc3 in the past.</p> | |
<ol> | |
<li><p>Retrieve the appropriate llvm-gcc-4.2-<i>version</i>.source.tar.gz | |
archive from the <a href="http://llvm.org/releases/">LLVM web | |
site</a>.</p> | |
<p>It is also possible to download the sources of the llvm-gcc front end | |
from a read-only mirror using subversion. To check out the 4.2 code | |
for first time use:</p> | |
<div class="doc_code"> | |
<pre> | |
svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk <i>dst-directory</i> | |
</pre> | |
</div> | |
<p>After that, the code can be be updated in the destination directory | |
using:</p> | |
<div class="doc_code"> | |
<pre>svn update</pre> | |
</div> | |
<p>The mirror is brought up to date every evening.</p></li> | |
<li>Follow the directions in the top-level <tt>README.LLVM</tt> file for | |
up-to-date instructions on how to build llvm-gcc. See below for building | |
with support for Ada or Fortran. | |
</ol> | |
</div> | |
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<h2><a name="ada">Building the Ada front-end</a></h2> | |
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<div> | |
<p>Building with support for Ada amounts to following the directions in the | |
top-level <tt>README.LLVM</tt> file, adding ",ada" to EXTRALANGS, for example: | |
<tt>EXTRALANGS=,ada</tt></p> | |
<p>There are some complications however:</p> | |
<ol> | |
<li><p>The only platform for which the Ada front-end is known to build is | |
32 bit intel x86 running linux. It is unlikely to build for other | |
systems without some work.</p></li> | |
<li><p>The build requires having a compiler that supports Ada, C and C++. | |
The Ada front-end is written in Ada so an Ada compiler is needed to | |
build it. Compilers known to work with the | |
<a href="http://llvm.org/releases/download.html">LLVM 2.7 release</a> | |
are <a href="http://gcc.gnu.org/releases.html">gcc-4.2</a> and the | |
2005, 2006 and 2007 versions of the | |
<a href="http://libre.adacore.com/">GNAT GPL Edition</a>. | |
<b>GNAT GPL 2008, gcc-4.3 and later will not work</b>. | |
The LLVM parts of llvm-gcc are written in C++ so a C++ compiler is | |
needed to build them. The rest of gcc is written in C. | |
Some linux distributions provide a version of gcc that supports all | |
three languages (the Ada part often comes as an add-on package to | |
the rest of gcc). Otherwise it is possible to combine two versions | |
of gcc, one that supports Ada and C (such as the | |
<a href="http://libre.adacore.com/">2007 GNAT GPL Edition</a>) | |
and another which supports C++, see below.</p></li> | |
<li><p>Because the Ada front-end is experimental, it is wise to build the | |
compiler with checking enabled. This causes it to run much slower, but | |
helps catch mistakes in the compiler (please report any problems using | |
<a href="http://llvm.org/bugs/">LLVM bugzilla</a>).</p></li> | |
<li><p>The Ada front-end <a href="http://llvm.org/PR2007">fails to | |
bootstrap</a>, due to lack of LLVM support for | |
<tt>setjmp</tt>/<tt>longjmp</tt> style exception handling (used | |
internally by the compiler), so you must specify | |
<tt>--disable-bootstrap</tt>.</p></li> | |
</ol> | |
<p>Supposing appropriate compilers are available, llvm-gcc with Ada support can | |
be built on an x86-32 linux box using the following recipe:</p> | |
<ol> | |
<li><p>Download the <a href="http://llvm.org/releases/download.html">LLVM source</a> | |
and unpack it:</p> | |
<pre class="doc_code"> | |
wget http://llvm.org/releases/2.7/llvm-2.7.tgz | |
tar xzf llvm-2.7.tgz | |
mv llvm-2.7 llvm | |
</pre> | |
<p>or <a href="GettingStarted.html#checkout">check out the | |
latest version from subversion</a>:</p> | |
<pre class="doc_code">svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</pre> | |
</li> | |
<li><p>Download the | |
<a href="http://llvm.org/releases/download.html">llvm-gcc-4.2 source</a> | |
and unpack it:</p> | |
<pre class="doc_code"> | |
wget http://llvm.org/releases/2.7/llvm-gcc-4.2-2.7.source.tgz | |
tar xzf llvm-gcc-4.2-2.7.source.tgz | |
mv llvm-gcc-4.2-2.7.source llvm-gcc-4.2 | |
</pre> | |
<p>or <a href="GettingStarted.html#checkout">check out the | |
latest version from subversion</a>:</p> | |
<pre class="doc_code"> | |
svn co http://llvm.org/svn/llvm-project/llvm-gcc-4.2/trunk llvm-gcc-4.2 | |
</pre> | |
</li> | |
<li><p>Make a build directory <tt>llvm-objects</tt> for llvm and make it the | |
current directory:</p> | |
<pre class="doc_code"> | |
mkdir llvm-objects | |
cd llvm-objects | |
</pre> | |
</li> | |
<li><p>Configure LLVM (here it is configured to install into <tt>/usr/local</tt>):</p> | |
<pre class="doc_code"> | |
../llvm/configure --prefix=<b>/usr/local</b> --enable-optimized --enable-assertions | |
</pre> | |
<p>If you have a multi-compiler setup and the C++ compiler is not the | |
default, then you can configure like this:</p> | |
<pre class="doc_code"> | |
CXX=<b>PATH_TO_C++_COMPILER</b> ../llvm/configure --prefix=<b>/usr/local</b> --enable-optimized --enable-assertions | |
</pre> | |
<p>To compile without checking (not recommended), replace | |
<tt>--enable-assertions</tt> with <tt>--disable-assertions</tt>.</p> | |
</li> | |
<li><p>Build LLVM:</p> | |
<pre class="doc_code"> | |
make | |
</pre> | |
</li> | |
<li><p>Install LLVM (optional):</p> | |
<pre class="doc_code"> | |
make install | |
</pre> | |
</li> | |
<li><p>Make a build directory <tt>llvm-gcc-4.2-objects</tt> for llvm-gcc and make it the | |
current directory:</p> | |
<pre class="doc_code"> | |
cd .. | |
mkdir llvm-gcc-4.2-objects | |
cd llvm-gcc-4.2-objects | |
</pre> | |
</li> | |
<li><p>Configure llvm-gcc (here it is configured to install into <tt>/usr/local</tt>). | |
The <tt>--enable-checking</tt> flag turns on sanity checks inside the compiler. | |
To turn off these checks (not recommended), replace <tt>--enable-checking</tt> | |
with <tt>--disable-checking</tt>. | |
Additional languages can be appended to the <tt>--enable-languages</tt> switch, | |
for example <tt>--enable-languages=ada,c,c++</tt>.</p> | |
<pre class="doc_code"> | |
../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c \ | |
--enable-checking --enable-llvm=$PWD/../llvm-objects \ | |
--disable-bootstrap --disable-multilib | |
</pre> | |
<p>If you have a multi-compiler setup, then you can configure like this:</p> | |
<pre class="doc_code"> | |
export CC=<b>PATH_TO_C_AND_ADA_COMPILER</b> | |
export CXX=<b>PATH_TO_C++_COMPILER</b> | |
../llvm-gcc-4.2/configure --prefix=<b>/usr/local</b> --enable-languages=ada,c \ | |
--enable-checking --enable-llvm=$PWD/../llvm-objects \ | |
--disable-bootstrap --disable-multilib | |
</pre> | |
</li> | |
<li><p>Build and install the compiler:</p> | |
<pre class="doc_code"> | |
make | |
make install | |
</pre> | |
</li> | |
</ol> | |
</div> | |
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<h2><a name="fortran">Building the Fortran front-end</a></h2> | |
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<div> | |
<p>To build with support for Fortran, follow the directions in the top-level | |
<tt>README.LLVM</tt> file, adding ",fortran" to EXTRALANGS, for example:</p> | |
<pre class="doc_code"> | |
EXTRALANGS=,fortran | |
</pre> | |
</div> | |
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<h2><a name="license">License Information</a></h2> | |
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<div> | |
<p> | |
The LLVM GCC frontend is licensed to you under the GNU General Public License | |
and the GNU Lesser General Public License. Please see the files COPYING and | |
COPYING.LIB for more details. | |
</p> | |
<p> | |
More information is <a href="FAQ.html#license">available in the FAQ</a>. | |
</p> | |
</div> | |
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