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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">Instructions</a></li>
23 <li><a href="#license">License Information</a></li>
26 <div class="doc_author">
27 <p>Written by Brian R. Gaeke and
28 <a href="http://nondot.org/sabre">Chris Lattner</a></p>
31 <!-- *********************************************************************** -->
32 <div class="doc_section">
33 <a name="cautionarynote">A Cautionary Note</a>
35 <!-- *********************************************************************** -->
37 <div class="doc_text">
38 <p>This document is intended to explain the process of building the
39 LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
40 would have to do this, for example, if you are porting LLVM to a new
41 architecture or operating system.</p>
43 <p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
44 process, and you should <b>only</b> try to do it if:</p>
47 <li>you really, really, really can't use the binaries we distribute</li>
48 <li>you are an elite GCC hacker.</li>
49 <li>you want to use the latest bits from CVS.</li>
52 <p>We welcome patches to help make this process simpler.</p>
55 <!--=========================================================================-->
56 <div class="doc_subsection">
57 <a name="cygwin">Building under Cygwin</a>
59 <!--=========================================================================-->
61 <div class="doc_text">
62 <p>If you are building LLVM and the GCC front-end under Cygwin, please note that
63 the LLVM and GCC makefiles do not correctly handle spaces in paths. To deal
64 with this issue, make sure that your LLVM and GCC source and build trees are
65 located in a top-level directory (like <tt>/cygdrive/c/llvm</tt> and
66 <tt>/cygdrive/c/llvm-cfrontend</tt>), not in a directory that contains a space
67 (which includes your "home directory", because it lives under the "Documents
68 and Settings" directory). We welcome patches to fix this issue.
70 <p>It has been found that the GCC 3.3.3 compiler provided with recent Cygwin
71 versions is incapable of compiling the LLVM GCC front-end correctly. If your
73 installation includes GCC 3.3.3, we <i>strongly</i> recommend that you download
74 GCC 3.4.3, build it separately, and use it for compiling the LLVM GCC front-end. This has been
75 shown to work correctly.</p>
76 <p>Some versions of Cygwin utilize an experimental version of GNU binutils that
77 will cause the GNU <tt>ld</tt> linker to fail an assertion when linking
78 components of the libstdc++. It is recommended that you replace the entire
79 binutils package with version 2.15 such that "<tt>ld --version</tt>" responds
81 <pre>GNU ld version 2.15</pre>
83 <pre>GNU ld version 2.15.91 20040725</pre>
86 <!--=========================================================================-->
87 <div class="doc_subsection"><a name="aix">Building under AIX</a></div>
88 <div class="doc_text">
89 <p>If you are building LLVM and the GCC front-end under AIX, do NOT use GNU
90 Binutils. They are not stable under AIX and may produce incorrect and/or
91 invalid code. Instead, use the system assembler and linker.
95 <!-- *********************************************************************** -->
96 <div class="doc_section">
97 <a name="instructions">Instructions</a>
99 <!-- *********************************************************************** -->
101 <div class="doc_text">
105 <p>Retrieve the appropriate llvm-gcc4-x.y.source.tar.gz archive from the llvm
107 <p>It is also possible to download the sources of the llvm-gcc4 front end from
108 a read-only mirror using subversion. To check out the code the first time use;
111 <tt>svn co svn://anonsvn.opensource.apple.com/svn/llvm <i>dst-directory</i></tt>
113 <p>After that, the code can be be updated in the destination directory using;
118 <p>The mirror is brought up to date every evening.</p>
120 <li><p>Configure and build the LLVM libraries and tools. There are two ways to
121 do this: either with <i>objdir</i> == <i>srcdir</i> or
122 <i>objdir</i> != <i>srcdir</i>. It is recommended
123 that <i>srcdir</i> be the same as <i>objdir</i> for your LLVM tree (but note
124 that you should always use <i>srcdir</i> != <i>objdir</i> for llvm-gcc):</p>
126 <li>With <i>objdir</i> != <i>srcdir</i>:<pre>
128 % <i>srcdir</i>/configure --prefix=/some/path/you/can/install/to [options...]
131 <li>With <i>objdir</i> == <i>srcdir</i>:<pre>
133 % ./configure --prefix=/some/path/you/can/install/to [options...]
137 <p>This will build all of the LLVM tools and libraries. The <tt>--prefix</tt>
138 option defaults to /usr/local (per configure standards) but unless you are a
139 system administrator, you probably won't be able to install LLVM there because
140 of permissions. Specify a path into which LLVM can be installed (e.g.
141 <tt>--prefix=/home/user/llvm</tt>).</p>
144 <li><p>Add the directory containing the tools to your PATH.</p>
146 % set path = ( `cd llvm/Debug/bin && pwd` $path )
149 <li><p>Unpack the C/C++ front-end source into cfrontend/src, either by
150 untar'ing a cfrontend.source.tar.gz file or checking out CVS into this
153 <li><p>Make "build" and "install" directories as siblings of the "src" tree:</p>
156 /usr/local/example/cfrontend/src
158 % mkdir build install
159 % set CFEINSTALL = `pwd`/install
163 <li><p>Configure, build, and install the GCC front-end:</p>
166 <b>Linux/x86:</b><br>
167 <b>Linux/IA-64:</b><br>
168 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
174 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
175 --disable-shared --enable-languages=c,c++ --program-prefix=llvm-
176 % gmake all; gmake install
179 <p><b>Cygwin/x86:</b></p>
183 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
184 --disable-shared --enable-languages=c,c++ --disable-c-mbchar \
185 --program-prefix=llvm-
186 % gmake all; gmake install
189 <p><b>Solaris/SPARC:</b></p>
192 The GCC front-end can be configured for either SPARC V8 (32 bit) or SPARC V9 (64
193 bit). This changes, among other things, the sizes of integer types and the
194 macros defined for conditional compilation.
198 The SPARC V8 ABI support is more robust than the V9 ABI support and can generate
199 SPARC V9 code. It is highly recommended that you use the V8 ABI with LLVM, as
201 note that Solaris has trouble with various wide (multibyte) character
202 functions from C as referenced from C++, so we typically configure with
203 --disable-c-mbchar (cf. <a href="http://llvm.org/PR206">Bug 206</a>).
208 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
209 --disable-shared --enable-languages=c,c++ --host=sparc-sun-solaris2.8 \
210 --disable-c-mbchar --program-prefix=llvm-
211 % gmake all; gmake install
214 <p><b>Common Problem:</b> You may get error messages regarding the fact
215 that LLVM does not support inline assembly. Here are two common
219 <li><p><b>Fix 1:</b> If you have system header files that include
220 inline assembly, you may have to modify them to remove the inline
221 assembly and install the modified versions in
222 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>
224 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
225 haven't tried yet, you will probably have to edit the appropriate
226 version of atomicity.h under
227 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
228 and apply a patch so that it does not use inline assembly.</li>
231 <p><b>Porting to a new architecture:</b> If you are porting the front-end
232 to a new architecture or compiling in a configuration that we have
233 not tried previously, there are probably several changes you will have to make
234 to the GCC target to get it to work correctly. These include:<p>
237 <li>Often targets include special assembler or linker flags which
238 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
239 just be removed.</li>
240 <li>LLVM currently does not support any floating point values other than
241 32-bit and 64-bit IEEE floating point. The primary effect of this is
242 that you may have to map "long double" onto "double".</li>
243 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
244 These may need to be disabled.</li>
245 <li>No inline assembly for position independent code. At the LLVM level,
246 everything is position independent.</li>
247 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
248 <li>You may have to disable multilib support in your target. Using multilib
249 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
250 options to the link line, which do not relate to LLVM and confuse
251 <tt>gccld</tt>. To disable multilibs, delete any
252 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
253 <li>Did we mention that we don't support inline assembly? You'll probably
254 have to add some fixinclude hacks to disable it in the system
259 <li><p>Put <tt>$CFEINSTALL/bin</tt> into your <tt>PATH</tt> environment
262 <li>sh: <tt>export PATH=$CFEINSTALL/bin:$PATH</tt></li>
263 <li>csh: <tt>setenv PATH $CFEINSTALL/bin:$PATH</tt></li>
267 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
268 the same options as the last time. This will cause the configuration to now find
269 the newly built llvm-gcc and llvm-g++ executables. </p></li>
271 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
272 rebuilt, but it should build the runtime libraries. After the tree is
273 built, install the runtime libraries into your GCC front-end build tree.
274 These are the commands you need:</p>
277 % gmake -C runtime install-bytecode
280 <li><p>Optionally, build a symbol table for the newly installed runtime
281 libraries. Although this step is optional, you are strongly encouraged to
282 do this as the symbol tables will make a significant difference in your
283 link times. Use the <tt>llvm-ranlib</tt> tool to do this, as follows:</p>
286 % llvm-ranlib libiberty.a
287 % llvm-ranlib libstdc++.a
288 % llvm-ranlib libsupc++.a
289 % cd $CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm
290 % llvm-ranlib libgcc.a
291 % llvm-ranlib libgcov.a
294 <li><p>Test the newly-installed C frontend by one or more of the
297 <li> running the feature & regression tests via <tt>make check</tt></li>
298 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
299 <li> running the tests found in the <tt>llvm-test</tt> CVS module</li>
304 <!-- *********************************************************************** -->
305 <div class="doc_section">
306 <a name="license">License Information</a>
309 <div class="doc_text">
311 The LLVM GCC frontend is licensed to you under the GNU General Public License
312 and the GNU Lesser General Public License. Please see the files COPYING and
313 COPYING.LIB for more details.
317 The software also has the following additional copyrights:
322 Copyright (c) 2003, 2004, 2005 University of Illinois at Urbana-Champaign.
329 University of Illinois at Urbana-Champaign
333 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
334 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
335 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
336 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
337 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
338 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
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345 and its documentation for any purpose is hereby granted without fee,
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348 in supporting documentation. Hewlett-Packard Company makes no
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350 purpose. It is provided "as is" without express or implied warranty.
352 Copyright (c) 1996, 1997, 1998, 1999
353 Silicon Graphics Computer Systems, Inc.
355 Permission to use, copy, modify, distribute and sell this software
356 and its documentation for any purpose is hereby granted without fee,
357 provided that the above copyright notice appear in all copies and
358 that both that copyright notice and this permission notice appear
359 in supporting documentation. Silicon Graphics makes no
360 representations about the suitability of this software for any
361 purpose. It is provided "as is" without express or implied warranty.
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