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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>
21 <li><a href="#instructions">Instructions</a></li>
22 <li><a href="#license">License Information</a></li>
25 <div class="doc_author">
26 <p>Written by Brian R. Gaeke and
27 <a href="http://nondot.org/sabre">Chris Lattner</a></p>
30 <!-- *********************************************************************** -->
31 <div class="doc_section">
32 <a name="cautionarynote">A Cautionary Note</a>
34 <!-- *********************************************************************** -->
36 <div class="doc_text">
37 <p>This document is intended to explain the process of building the
38 LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
39 would have to do this, for example, if you are porting LLVM to a new
40 architecture or operating system.</p>
42 <p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
43 process, and you should <b>only</b> try to do it if:</p>
46 <li>you really, really, really can't use the binaries we distribute</li>
47 <li>you need GCC to fix some of the header files on your system</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 C 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.
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72 <div class="doc_section">
73 <a name="instructions">Instructions</a>
75 <!-- *********************************************************************** -->
77 <div class="doc_text">
80 <li><p>Configure and build the LLVM libraries and tools using:</p>
83 % ./configure [options...]
86 <p>This will build all of the LLVM tools and libraries.</p></li>
88 <li><p>Add the directory containing the tools to your PATH.</p>
90 % set path = ( `cd llvm/tools/Debug && pwd` $path )
93 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
95 <li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
98 /usr/local/example/cfrontend/src
100 % mkdir build install
101 % set CFEINSTALL = `pwd`/install
105 <li><p>Configure, build, and install the C front-end:</p>
108 <b>Linux/x86:</b><br>
109 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
115 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
116 --disable-shared --enable-languages=c,c++
118 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
119 % gmake all; gmake install
122 <p><b>Cygwin/x86:</b></p>
126 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
127 --disable-shared --enable-languages=c,c++ --disable-c-mbchar
129 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
130 % gmake all; gmake install
133 <p><b>Solaris/SPARC:</b></p>
136 For Solaris/SPARC, LLVM only supports the SPARC V9. Therefore, the
137 configure command line should specify sparcv9, as shown below. Also,
138 note that Solaris has trouble with various wide (multibyte) character
139 functions from C as referenced from C++, so we typically configure with
140 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
145 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
146 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
149 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
150 % gmake all; gmake install
153 <p><b>Common Problem:</b> You may get error messages regarding the fact
154 that LLVM does not support inline assembly. Here are two common
158 <li><p><b>Fix 1:</b> If you have system header files that include
159 inline assembly, you may have to modify them to remove the inline
160 assembly, and install the modified versions in
161 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</li>
163 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
164 haven't tried yet, you will probably have to edit the appropriate
165 version of atomicity.h under
166 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
167 and apply a patch so that it does not use inline assembly.</li>
170 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
171 to a new architecture, or compiling in a different configuration that we have
172 previously, there are probably several changes you will have to make to the GCC
173 target to get it to work correctly. These include:<p>
176 <li>Often targets include special or assembler linker flags which
177 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
178 just be removed.</li>
179 <li>LLVM currently does not support any floating point values other than
180 32-bit and 64-bit IEEE floating point. The primary effect of this is
181 that you may have to map "long double" onto "double".</li>
182 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
183 These may need to be disabled.</li>
184 <li>No inline assembly for position independent code. At the LLVM level,
185 everything is position independent.</li>
186 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
187 <li>You may have to disable multilib support in your target. Using multilib
188 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
189 options to the link line, which do not relate to LLVM and confuse
190 <tt>gccld</tt>. To disable multilibs, delete any
191 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
192 <li>Did we mention that we don't support inline assembly? You'll probably
193 have to add some fixinclude hacks to disable it in the system
198 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
199 the <code>--with-llvmgccdir=$CFEINSTALL</code> option to specify the path
200 to the newly built C front-end.</p></li>
202 <li><p>If you edited header files during the C/C++ front-end build as
203 described in "Fix 1" above, you must now copy those header files from
204 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
205 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
206 (This should be the "include" directory in the same directory as the
207 libgcc.a library, which you can find by running
208 <code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
210 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
211 rebuilt, but it should build the runtime libraries. After the tree is
212 built, install the runtime libraries into your C front-end build tree.
213 These are the commands you need.</p>
216 % mkdir $CFEINSTALL/bytecode-libs
217 % gmake -C runtime install-bytecode
218 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
221 <li><p>Test the newly-installed C frontend by one or more of the
224 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
225 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
226 test/Programs</code></li>
231 <!-- *********************************************************************** -->
232 <div class="doc_section">
233 <a name="license">License Information</a>
236 <div class="doc_text">
238 The LLVM GCC frontend is licensed to you under the GNU General Public License
239 and the GNU Lesser General Public License. Please see the files COPYING and
240 COPYING.LIB for more details.
244 The software also has the following additional copyrights:
249 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
256 University of Illinois at Urbana-Champaign
258 http://llvm.cs.uiuc.edu
260 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
261 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
262 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
263 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
264 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
265 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
269 Hewlett-Packard Company
271 Permission to use, copy, modify, distribute and sell this software
272 and its documentation for any purpose is hereby granted without fee,
273 provided that the above copyright notice appear in all copies and
274 that both that copyright notice and this permission notice appear
275 in supporting documentation. Hewlett-Packard Company makes no
276 representations about the suitability of this software for any
277 purpose. It is provided "as is" without express or implied warranty.
279 Copyright (c) 1996, 1997, 1998, 1999
280 Silicon Graphics Computer Systems, Inc.
282 Permission to use, copy, modify, distribute and sell this software
283 and its documentation for any purpose is hereby granted without fee,
284 provided that the above copyright notice appear in all copies and
285 that both that copyright notice and this permission notice appear
286 in supporting documentation. Silicon Graphics makes no
287 representations about the suitability of this software for any
288 purpose. It is provided "as is" without express or implied warranty.
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