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| <title>Building the LLVM GCC Front-End</title> |
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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> |
| |
| <!-- *********************************************************************** --> |
| <h2><a name="instructions">Building llvm-gcc from Source</a></h2> |
| <!-- *********************************************************************** --> |
| |
| <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> |
| |
| <!-- *********************************************************************** --> |
| <h2><a name="ada">Building the Ada front-end</a></h2> |
| <!-- *********************************************************************** --> |
| |
| <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> |
| |
| <!-- *********************************************************************** --> |
| <h2><a name="fortran">Building the Fortran front-end</a></h2> |
| <!-- *********************************************************************** --> |
| |
| <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> |
| |
| <!-- *********************************************************************** --> |
| <h2><a name="license">License Information</a></h2> |
| <!-- *********************************************************************** --> |
| |
| <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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