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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>
51 <p>We welcome patches to help make this process simpler.</p>
54 <!--=========================================================================-->
55 <div class="doc_subsection">
56 <a name="cygwin">Building under Cygwin</a>
58 <!--=========================================================================-->
60 <div class="doc_text">
61 <p>If you are building LLVM and the GCC front-end under Cygwin, please note that
62 the LLVM and GCC makefiles do not correctly handle spaces in paths. To deal
63 with this issue, make sure that your LLVM and GCC source and build trees are
64 located in a top-level directory (like <tt>/cygdrive/c/llvm</tt> and
65 <tt>/cygdrive/c/llvm-cfrontend</tt>), not in a directory that contains a space
66 (which includes your "home directory", because it lives under the "Documents
67 and Settings" directory). We welcome patches to fix this issue.
69 <p>It has been found that the GCC 3.3.3 compiler provided with recent Cygwin
70 versions is incapable of compiling the LLVM CFE correctly. If your Cygwin
71 installation includes GCC 3.3.3 we <i>strongly</i> recommend that you download
72 GCC 3.4.3, build it separately, and use it for compiling LLVM CFE. This has been
73 shown to work correctly.</p>
74 <p>Some versions of Cygwin utilize an experimental version of GNU binutils that
75 will cause the GNU <tt>ld</tt> linker to fail an assertion when linking
76 components of the libstdc++. It is recommended that you replace the entire
77 binutils package with version 2.15 such that "<tt>ld --version</tt>" responds
79 <pre>GNU ld version 2.15</pre>
81 <pre>GNU ld version 2.15.91 20040725</pre>
84 <!--=========================================================================-->
85 <div class="doc_subsection"><a name="aix">Building under AIX</a></div>
86 <div class="doc_text">
87 <p>If you are building LLVM and the GCC front-end under AIX, do NOT use GNU
88 Binutils. They are not stable under AIX and may produce incorrect and/or
89 invalid code. Instead, use the system assembler and linker.
93 <!-- *********************************************************************** -->
94 <div class="doc_section">
95 <a name="instructions">Instructions</a>
97 <!-- *********************************************************************** -->
99 <div class="doc_text">
102 <li><p>Configure and build the LLVM libraries and tools. There are two ways to
103 do this: either with <i>objdir</i> == <i>srcdir</i> or not. It is recommended
104 that <i>srcdir</i> not be the same as <i>objdir</i>:</p>
106 <li>With <i>objdir</i> != <i>srcdir</i>:<pre>
108 % <i>srcdir</i>/configure --prefix=/some/path/you/can/install/to [options...]
111 <li>With <i>objdir</i> == <i>srcdir</i>:<pre>
113 % ./configure --prefix=/some/path/you/can/install/to [options...]
117 <p>This will build all of the LLVM tools and libraries. The <tt>--prefix</tt>
118 option defaults to /usr/local (per configure standards) but unless you are a
119 system administrator, you probably won't be able to install LLVM there because
120 of permissions. Specify a path into which LLVM can be installed (e.g.
121 <tt>--prefix=/home/user/llvm</tt>).</p>
124 <li><p>Add the directory containing the tools to your PATH.</p>
126 % set path = ( `cd llvm/Debug/bin && pwd` $path )
129 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
131 <li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
134 /usr/local/example/cfrontend/src
136 % mkdir build install
137 % set CFEINSTALL = `pwd`/install
141 <li><p>Configure, build, and install the GCC front-end:</p>
144 <b>Linux/x86:</b><br>
145 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
151 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
152 --disable-shared --enable-languages=c,c++ --program-prefix=llvm-
153 % gmake all; gmake install
156 <p><b>Cygwin/x86:</b></p>
160 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
161 --disable-shared --enable-languages=c,c++ --disable-c-mbchar \
162 --program-prefix=llvm-
163 % gmake all; gmake install
166 <p><b>Solaris/SPARC:</b></p>
169 For Solaris/SPARC, LLVM only supports the SPARC V9 architecture. Therefore,
170 the configure command line should specify sparcv9, as shown below. Also,
171 note that Solaris has trouble with various wide (multibyte) character
172 functions from C as referenced from C++, so we typically configure with
173 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
178 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
179 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
180 --disable-c-mbchar --program-prefix=llvm-
181 % gmake all; gmake install
184 <p><b>Common Problem:</b> You may get error messages regarding the fact
185 that LLVM does not support inline assembly. Here are two common
189 <li><p><b>Fix 1:</b> If you have system header files that include
190 inline assembly, you may have to modify them to remove the inline
191 assembly and install the modified versions in
192 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>
194 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
195 haven't tried yet, you will probably have to edit the appropriate
196 version of atomicity.h under
197 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
198 and apply a patch so that it does not use inline assembly.</li>
201 <p><b>Porting to a new architecture:</b> If you are porting the front-end
202 to a new architecture or compiling in a configuration that we have
203 not tried previously, there are probably several changes you will have to make
204 to the GCC target to get it to work correctly. These include:<p>
207 <li>Often targets include special assembler or linker flags which
208 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
209 just be removed.</li>
210 <li>LLVM currently does not support any floating point values other than
211 32-bit and 64-bit IEEE floating point. The primary effect of this is
212 that you may have to map "long double" onto "double".</li>
213 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
214 These may need to be disabled.</li>
215 <li>No inline assembly for position independent code. At the LLVM level,
216 everything is position independent.</li>
217 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
218 <li>You may have to disable multilib support in your target. Using multilib
219 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
220 options to the link line, which do not relate to LLVM and confuse
221 <tt>gccld</tt>. To disable multilibs, delete any
222 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
223 <li>Did we mention that we don't support inline assembly? You'll probably
224 have to add some fixinclude hacks to disable it in the system
229 <li><p>Put <tt>$CFEINSTALL/bin</tt> into your <tt>PATH</tt> environment
232 <li>sh: <tt>export PATH=$CFEINSTALL/bin:$PATH</tt></li>
233 <li>csh: <tt>setenv PATH $CFEINSTALL/bin:$PATH</tt></li>
237 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
238 the same options as the last time. This will cause the configuration to now find
239 the newly built llvm-gcc and llvm-g++ executables. </p></li>
241 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
242 rebuilt, but it should build the runtime libraries. After the tree is
243 built, install the runtime libraries into your GCC front-end build tree.
244 These are the commands you need.</p>
247 % gmake -C runtime install-bytecode
250 <li><p>Optionally, build a symbol table for the newly installed runtime
251 libraries. Although this step is optional, you are strongly encouraged to
252 do this as the symbol tables will make a significant difference in your
253 link times. Use the <tt>llvm-ranlib</tt> tool to do this, as follows:</p>
256 % llvm-ranlib libiberty.a
257 % llvm-ranlib libstdc++.a
258 % llvm-ranlib libsupc++.a
259 % cd $CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm
260 % llvm-ranlib libgcc.a
261 % llvm-ranlib libgcov.a
264 <li><p>Test the newly-installed C frontend by one or more of the
267 <li> running the feature & regression tests via <tt>make check</tt></li>
268 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
269 <li> running the tests found in the <tt>llvm-test</tt> CVS module</li>
274 <!-- *********************************************************************** -->
275 <div class="doc_section">
276 <a name="license">License Information</a>
279 <div class="doc_text">
281 The LLVM GCC frontend is licensed to you under the GNU General Public License
282 and the GNU Lesser General Public License. Please see the files COPYING and
283 COPYING.LIB for more details.
287 The software also has the following additional copyrights:
292 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
299 University of Illinois at Urbana-Champaign
301 http://llvm.cs.uiuc.edu
303 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
304 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
305 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
306 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
307 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
308 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
312 Hewlett-Packard Company
314 Permission to use, copy, modify, distribute and sell this software
315 and its documentation for any purpose is hereby granted without fee,
316 provided that the above copyright notice appear in all copies and
317 that both that copyright notice and this permission notice appear
318 in supporting documentation. Hewlett-Packard Company makes no
319 representations about the suitability of this software for any
320 purpose. It is provided "as is" without express or implied warranty.
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323 Silicon Graphics Computer Systems, Inc.
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327 provided that the above copyright notice appear in all copies and
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