<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <link rel="stylesheet" href="llvm.css" type="text/css" media="screen"> <title>Building the LLVM GCC Front-End</title> </head> <body> <div class="doc_title"> Building the LLVM GCC Front-End </div> <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> <!-- *********************************************************************** --> <h1><a name="instructions">Building llvm-gcc from Source</a></h1> <!-- *********************************************************************** --> <div class="doc_text"> <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> <!-- *********************************************************************** --> <h1><a name="ada">Building the Ada front-end</a></h1> <!-- *********************************************************************** --> <div class="doc_text"> <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> <!-- *********************************************************************** --> <h1><a name="fortran">Building the Fortran front-end</a></h1> <!-- *********************************************************************** --> <div class="doc_text"> <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> <!-- *********************************************************************** --> <h1><a name="license">License Information</a></h1> <!-- *********************************************************************** --> <div class="doc_text"> <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> <!-- *********************************************************************** --> <hr> <address> <a href="http://jigsaw.w3.org/css-validator/check/referer"><img src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a> <a href="http://validator.w3.org/check/referer"><img src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a> <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br> Last modified: $Date$ </address> </body> </html>