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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.
71 <!--=========================================================================-->
72 <div class="doc_subsection">
73 <a name="aix">Building under AIX</a>
75 <!--=========================================================================-->
77 <div class="doc_text">
78 <p>If you are building LLVM and the GCC front-end under AIX, do NOT use GNU
79 Binutils. They are not stable under AIX and may produce incorrect and/or
80 invalid code. Instead, use the system assembler and linker.
84 <!-- *********************************************************************** -->
85 <div class="doc_section">
86 <a name="instructions">Instructions</a>
88 <!-- *********************************************************************** -->
90 <div class="doc_text">
93 <li><p>Configure and build the LLVM libraries and tools using:</p>
96 % ./configure --prefix=/some/path/you/can/install/to [options...]
99 <p>This will build all of the LLVM tools and libraries. The <tt>--prefix</tt>
100 option defaults to /usr/local (per configure standards) but unless you are a
101 system administrator, you probably won't be able to install LLVM there because
102 of permissions. Specify a path into which LLVM can be installed (e.g.
103 <tt>--prefix=/home/user/llvm</tt>).</p>
106 <li><p>Add the directory containing the tools to your PATH.</p>
108 % set path = ( `cd llvm/Debug/bin && pwd` $path )
111 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
113 <li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
116 /usr/local/example/cfrontend/src
118 % mkdir build install
119 % set CFEINSTALL = `pwd`/install
123 <li><p>Configure, build, and install the GCC front-end:</p>
126 <b>Linux/x86:</b><br>
127 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
133 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
134 --disable-shared --enable-languages=c,c++
136 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
137 % gmake all; gmake install
140 <p><b>Cygwin/x86:</b></p>
144 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
145 --disable-shared --enable-languages=c,c++ --disable-c-mbchar
147 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
148 % gmake all; gmake install
151 <p><b>Solaris/SPARC:</b></p>
154 For Solaris/SPARC, LLVM only supports the SPARC V9 architecture. Therefore,
155 the configure command line should specify sparcv9, as shown below. Also,
156 note that Solaris has trouble with various wide (multibyte) character
157 functions from C as referenced from C++, so we typically configure with
158 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
163 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
164 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
167 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
168 % gmake all; gmake install
171 <p><b>Common Problem:</b> You may get error messages regarding the fact
172 that LLVM does not support inline assembly. Here are two common
176 <li><p><b>Fix 1:</b> If you have system header files that include
177 inline assembly, you may have to modify them to remove the inline
178 assembly and install the modified versions in
179 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>
181 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
182 haven't tried yet, you will probably have to edit the appropriate
183 version of atomicity.h under
184 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
185 and apply a patch so that it does not use inline assembly.</li>
188 <p><b>Porting to a new architecture:</b> If you are porting the front-end
189 to a new architecture or compiling in a configuration that we have
190 not tried previously, there are probably several changes you will have to make
191 to the GCC target to get it to work correctly. These include:<p>
194 <li>Often targets include special assembler or linker flags which
195 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
196 just be removed.</li>
197 <li>LLVM currently does not support any floating point values other than
198 32-bit and 64-bit IEEE floating point. The primary effect of this is
199 that you may have to map "long double" onto "double".</li>
200 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
201 These may need to be disabled.</li>
202 <li>No inline assembly for position independent code. At the LLVM level,
203 everything is position independent.</li>
204 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
205 <li>You may have to disable multilib support in your target. Using multilib
206 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
207 options to the link line, which do not relate to LLVM and confuse
208 <tt>gccld</tt>. To disable multilibs, delete any
209 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
210 <li>Did we mention that we don't support inline assembly? You'll probably
211 have to add some fixinclude hacks to disable it in the system
216 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
217 the <code>--with-llvmgccdir=$CFEINSTALL</code> option to specify the path
218 to the newly built GCC front-end.</p></li>
220 <li><p>If you edited header files during the C/C++ front-end build as
221 described in "Fix 1" above, you must now copy those header files from
222 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
223 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
224 (This should be the "include" directory in the same directory as the
225 libgcc.a library, which you can find by running
226 <code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
228 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
229 rebuilt, but it should build the runtime libraries. After the tree is
230 built, install the runtime libraries into your GCC front-end build tree.
231 These are the commands you need.</p>
234 % mkdir $CFEINSTALL/lib
235 % gmake -C runtime install-bytecode
236 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/lib
239 <li><p>Optionally, build a symbol table for the newly installed runtime
240 libraries. Although this step is optional, you are encouraged to do this as the
241 symbol tables will make a significant difference in your link times. Use
242 the <tt>llvm-ranlib</tt> tool to do this, as follows:</p>
245 % llvm-ranlib libiberty.a
246 % llvm-ranlib libstdc++.a
247 % llvm-ranlib libsupc++.a
248 % cd $CFEINSTALL/lib/<i>target-triplet</i>/3.4-llvm
249 % llvm-ranlib libgcc.a
250 % llvm-ranlib libgcov.a
253 <li><p>Test the newly-installed C frontend by one or more of the
256 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
257 <li> running the regression tests in <tt>llvm/test</tt>
258 <li> running the tests found in the <tt>llvm-test</tt> CVS module</li>
263 <!-- *********************************************************************** -->
264 <div class="doc_section">
265 <a name="license">License Information</a>
268 <div class="doc_text">
270 The LLVM GCC frontend is licensed to you under the GNU General Public License
271 and the GNU Lesser General Public License. Please see the files COPYING and
272 COPYING.LIB for more details.
276 The software also has the following additional copyrights:
281 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
288 University of Illinois at Urbana-Champaign
290 http://llvm.cs.uiuc.edu
292 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
293 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
294 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
295 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
296 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
297 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
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307 in supporting documentation. Hewlett-Packard Company makes no
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309 purpose. It is provided "as is" without express or implied warranty.
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312 Silicon Graphics Computer Systems, Inc.
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. Silicon Graphics 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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