1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
5 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
6 <link rel="stylesheet" href="llvm.css" type="text/css" media="screen">
7 <title>Bootstrapping the LLVM C/C++ Front-End</title>
11 <div class="doc_title">
12 Bootstrapping the LLVM C/C++ Front-End
16 <li><a href="#cautionarynote">A Cautionary Note</a>
18 <li><a href="#cygwin">Building under Cygwin</a></li>
19 <li><a href="#aix">Building under AIX</a></li>
22 <li><a href="#instructions">llvm-gcc4 Instructions</a></li>
23 <li><a href="#llvm-gcc3-instructions">llvm-gcc3 Instructions</a></li>
24 <li><a href="#license">License Information</a></li>
27 <div class="doc_author">
28 <p>Written by Brian R. Gaeke and
29 <a href="http://nondot.org/sabre">Chris Lattner</a></p>
32 <!-- *********************************************************************** -->
33 <div class="doc_section">
34 <a name="cautionarynote">A Cautionary Note</a>
36 <!-- *********************************************************************** -->
38 <div class="doc_text">
40 <p>This document is intended to explain the process of building the LLVM C/C++
41 front-end from its source code. You have to do this, for example, if you are
42 porting LLVM to a new architecture or operating system, if you are working from
43 Top-Of-Tree CVS/SVN, or if there is no precompiled snapshot available.</p>
45 <p><b>NOTE:</b> This is currently a somewhat fragile, error-prone process, and
46 you should <b>only</b> try to do it if:</p>
49 <li>you really, <em>really</em>, <b><em>really</em></b> can't use the
50 binaries we distribute</li>
51 <li>you are an elite GCC hacker.</li>
52 <li>you want to use the latest bits from CVS.</li>
55 <p>We welcome patches to help make this process simpler.</p>
59 <!--=========================================================================-->
60 <div class="doc_subsection">
61 <a name="cygwin">Building under Cygwin</a>
63 <!--=========================================================================-->
65 <div class="doc_text">
67 <p>If you are building LLVM and the GCC front-end under Cygwin, please note that
68 the LLVM and GCC makefiles do not correctly handle spaces in paths. To deal
69 with this issue, make sure that your LLVM and GCC source and build trees are
70 located in a top-level directory (like <tt>/cygdrive/c/llvm</tt> and
71 <tt>/cygdrive/c/llvm-cfrontend</tt>), not in a directory that contains a space
72 (which includes your "home directory", because it lives under the "Documents and
73 Settings" directory). We welcome patches to fix this issue.</p>
75 <p>It has been found that the GCC 3.3.3 compiler provided with recent Cygwin
76 versions is incapable of compiling the LLVM GCC front-end correctly. If your
77 Cygwin installation includes GCC 3.3.3, we <em>strongly</em> recommend that you
78 download GCC 3.4.3, build it separately, and use it for compiling the LLVM GCC
79 front-end. This has been shown to work correctly.</p>
81 <p>Some versions of Cygwin utilize an experimental version of GNU binutils that
82 will cause the GNU <tt>ld</tt> linker to fail an assertion when linking
83 components of the libstdc++. It is recommended that you replace the entire
84 binutils package with version 2.15 such that "<tt>ld --version</tt>" responds
87 <div class="doc_code">
88 <pre>GNU ld version 2.15</pre>
93 <div class="doc_code">
94 <pre>GNU ld version 2.15.91 20040725</pre>
99 <!--=========================================================================-->
100 <div class="doc_subsection"><a name="aix">Building under AIX</a></div>
102 <div class="doc_text">
104 <p>If you are building LLVM and the GCC front-end under AIX, do NOT use GNU
105 Binutils. They are not stable under AIX and may produce incorrect and/or
106 invalid code. Instead, use the system assembler and linker.</p>
110 <!-- *********************************************************************** -->
111 <div class="doc_section">
112 <a name="instructions">llvm-gcc4 Instructions</a>
114 <!-- *********************************************************************** -->
116 <div class="doc_text">
118 <p>This section describes how to aquire and build llvm-gcc4, which is based on
119 the GCC 4.0.1 front-end. This front-end supports C, C++, Objective-C, and
120 Objective-C++. Note that the instructions for building this front-end are
121 completely different than those for building llvm-gcc3.</p>
124 <li><p>Retrieve the appropriate llvm-gcc4-x.y.source.tar.gz archive from the
127 <p>It is also possible to download the sources of the llvm-gcc4 front end
128 from a read-only mirror using subversion. To check out the code the
131 <div class="doc_code">
133 svn co svn://anonsvn.opensource.apple.com/svn/llvm/trunk <i>dst-directory</i>
137 <p>After that, the code can be be updated in the destination directory
140 <div class="doc_code">
141 <pre>svn update</pre>
144 <p>The mirror is brought up to date every evening.</p></li>
146 <li>Follow the directions in the top-level <tt>README.LLVM</tt> file for
147 up-to-date instructions on how to build llvm-gcc4.</li>
152 <!-- *********************************************************************** -->
153 <div class="doc_section">
154 <a name="llvm-gcc3-instructions">llvm-gcc3 Instructions</a>
156 <!-- *********************************************************************** -->
158 <div class="doc_text">
161 <li>Aquire llvm-gcc3 from <a href="GettingStarted.html#checkout">LLVM CVS</a>
162 or from a <a href="http://llvm.org/releases/">release tarball</a>.</li>
164 <li><p>Configure and build the LLVM libraries and tools. There are two ways to
165 do this: either with <tt><i>objdir</i> == <i>srcdir</i></tt> or
166 <tt><i>objdir</i> != <i>srcdir</i></tt>. It is recommended that
167 <tt><i>srcdir</i></tt> be the same as <tt><i>objdir</i></tt> for your
168 LLVM tree (but note that you should always use <tt><i>srcdir</i> !=
169 <i>objdir</i></tt> for llvm-gcc):</p>
172 <li><p>With <tt><i>objdir</i> != <i>srcdir</i></tt>:</p>
174 <div class="doc_code">
177 % <i>srcdir</i>/configure --prefix=/some/path/you/can/install/to [options...]
182 <li><p>With <tt><i>objdir</i> == <i>srcdir</i></tt>:</p>
184 <div class="doc_code">
187 % ./configure --prefix=/some/path/you/can/install/to [options...]
194 <p>This will build all of the LLVM tools and libraries. The
195 <tt>--prefix</tt> option defaults to <tt>/usr/local</tt> (per configure
196 standards) but unless you are a system administrator, you probably
197 won't be able to install LLVM there because of permissions. Specify a
198 path into which LLVM can be installed
199 (e.g. <tt>--prefix=/home/user/llvm</tt>).</p></li>
200 <li><p>Add the directory containing the tools to your PATH.</p>
202 <div class="doc_code">
205 % set path = ( `cd llvm/Debug/bin && pwd` $path )
209 % export PATH=`cd llvm/Debug/bin && pwd`:$PATH
214 <li><p>Unpack the C/C++ front-end source, either by
215 untar'ing/unzipping a tar.gz file or checking out CVS into this
217 <li><p>Make "build" and "install" directories as siblings of the "src"
220 <div class="doc_code">
224 /usr/local/example/llvm-gcc3.4/src
226 % mkdir build install
227 % set CFEINSTALL = `pwd`/install
232 /usr/local/example/llvm-gcc3.4/src
234 % mkdir build install
235 % export CFEINSTALL=`pwd`/install
240 <li><p>Configure, build, and install the GCC front-end:</p>
243 <b>Linux/x86:</b><br>
244 <b>Linux/IA-64:</b><br>
245 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
249 <div class="doc_code">
252 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
253 --disable-shared --enable-languages=c,c++ --program-prefix=llvm-
254 % gmake all; gmake install
258 <p><b>Cygwin/x86:</b></p>
260 <div class="doc_code">
263 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
264 --disable-shared --enable-languages=c,c++ --disable-c-mbchar \
265 --program-prefix=llvm-
266 % gmake all; gmake install
270 <p><b>Solaris/SPARC:</b></p>
272 <p>The GCC front-end can be configured for either SPARC V8 (32 bit) or
273 SPARC V9 (64 bit). This changes, among other things, the sizes of
274 integer types and the macros defined for conditional compilation.</p>
276 <p>The SPARC V8 ABI support is more robust than the V9 ABI support and can
277 generate SPARC V9 code. It is highly recommended that you use the V8
278 ABI with LLVM, as shown below. Also, note that Solaris has trouble
279 with various wide (multibyte) character functions from C as referenced
280 from C++, so we typically configure with --disable-c-mbchar (cf. <a
281 href="http://llvm.org/PR206">Bug 206</a>).</p>
283 <div class="doc_code">
286 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
287 --disable-shared --enable-languages=c,c++ --host=sparc-sun-solaris2.8 \
288 --disable-c-mbchar --program-prefix=llvm-
289 % gmake all; gmake install
293 <p><b>Common Problem:</b> You may get error messages regarding the fact
294 that LLVM does not support inline assembly. Here are two common
298 <li><p><b>Fix 1:</b> If you have system header files that include inline
299 assembly, you may have to modify them to remove the inline assembly
300 and install the modified versions in
301 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>
303 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
304 haven't tried yet, you will probably have to edit the appropriate
305 version of atomicity.h under
306 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
307 and apply a patch so that it does not use inline assembly.</li>
310 <p><b>Porting to a new architecture:</b> If you are porting the front-end
311 to a new architecture or compiling in a configuration that we have not
312 tried previously, there are probably several changes you will have to
313 make to the GCC target to get it to work correctly. These include:</p>
316 <li>Often targets include special assembler or linker flags which
317 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general,
318 these can just be removed.</li>
320 <li>LLVM currently does not support any floating point values other than
321 32-bit and 64-bit IEEE floating point. The primary effect of this
322 is that you may have to map "long double" onto "double".</li>
324 <li>The profiling hooks in GCC do not apply at all to the LLVM
325 front-end. These may need to be disabled.</li>
327 <li>No inline assembly for position independent code. At the LLVM
328 level, everything is position independent.</li>
330 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
332 <li>You may have to disable multilib support in your target. Using
333 multilib support causes the GCC compiler driver to add a lot of
334 "<tt>-L</tt>" options to the link line, which do not relate to LLVM
335 and confuse <tt>gccld</tt>. To disable multilibs, delete any
336 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
338 <li>Did we mention that we don't support inline assembly? You'll
339 probably have to add some fixinclude hacks to disable it in the
343 <li><p>Put <tt>$CFEINSTALL/bin</tt> into your <tt>PATH</tt> environment
346 <div class="doc_code">
349 % setenv PATH $CFEINSTALL/bin:$PATH
353 % export PATH=$CFEINSTALL/bin:$PATH
358 <li><p>Go back into the LLVM source tree proper. Rerun configure, using the
359 same options as the last time. This will cause the configuration to now
360 find the newly built llvm-gcc and llvm-g++ executables. </p></li>
362 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
363 rebuilt, but it should build the runtime libraries. After the tree is
364 built, install the runtime libraries into your GCC front-end build tree.
365 These are the commands you need:</p>
367 <div class="doc_code">
370 % gmake -C runtime install-bytecode
375 <li><p>Optionally, build a symbol table for the newly installed runtime
376 libraries. Although this step is optional, you are strongly encouraged to
377 do this as the symbol tables will make a significant difference in your
378 link times. Use the <tt>llvm-ranlib</tt> tool to do this, as follows:</p>
380 <div class="doc_code">
383 % llvm-ranlib libiberty.a
384 % llvm-ranlib libstdc++.a
385 % llvm-ranlib libsupc++.a
386 % cd $CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm
387 % llvm-ranlib libgcc.a
388 % llvm-ranlib libgcov.a
393 <li><p>Test the newly-installed C frontend by one or more of the following
397 <li>running the feature & regression tests via <tt>make
399 <li>compiling and running a "hello, LLVM" program in C and C++.</li>
400 <li>running the tests found in the <tt>llvm-test</tt> CVS module</li>
406 <!-- *********************************************************************** -->
407 <div class="doc_section">
408 <a name="license">License Information</a>
411 <div class="doc_text">
413 The LLVM GCC frontend is licensed to you under the GNU General Public License
414 and the GNU Lesser General Public License. Please see the files COPYING and
415 COPYING.LIB for more details.
419 More information is <a href="FAQ.html#license">available in the FAQ</a>.
424 <!-- *********************************************************************** -->
428 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
429 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
430 <a href="http://validator.w3.org/check/referer"><img
431 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
434 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
435 Last modified: $Date$