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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, but you will see
87 warnings about missing the C front-end (certain runtime libraries can't
88 be built without it). Ignore these warnings for now.</p></li>
90 <li><p>Add the directory containing the tools to your PATH.</p>
92 % set path = ( `cd llvm/tools/Debug && pwd` $path )
95 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
97 <li><p>Make "build" and "install" directories as siblings of the "src"
101 /usr/local/example/cfrontend/src
103 % mkdir build install
104 % set CFEINSTALL = `pwd`/install
108 <li><p>Configure, build, and install the C front-end:</p>
111 <b>Linux/x86:</b><br>
112 <b>MacOS X/PowerPC</b> (requires dlcompat library):
117 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls --disable-shared \
118 --enable-languages=c,c++
120 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
121 % gmake all; gmake install
124 <p><b>Cygwin/x86:</b></p>
128 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls --disable-shared \
129 --enable-languages=c,c++ --disable-c-mbchar
131 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
132 % gmake all; gmake install
135 <p><b>Solaris/SPARC:</b></p>
138 For Solaris/SPARC, LLVM only supports the SPARC V9. Therefore, the
139 configure command line should specify sparcv9, as shown below. Also,
140 note that Solaris has trouble with various wide (multibyte) character
141 functions from C as referenced from C++, so we typically configure with
142 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
147 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
148 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
151 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
152 % gmake all; gmake install
155 <p><b>Common Problem:</b> You may get error messages regarding the fact
156 that LLVM does not support inline assembly. Here are two common
160 <li><p><b>Fix 1:</b> If you have system header files that include
161 inline assembly, you may have to modify them to remove the inline
162 assembly, and install the modified versions in
163 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</li>
165 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
166 haven't tried yet, you will probably have to edit the appropriate
167 version of atomicity.h under
168 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
169 and apply a patch so that it does not use inline assembly.</li>
172 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
173 to a new architecture, or compiling in a different configuration that we have
174 previously, there are probably several changes you will have to make to the GCC
175 target to get it to work correctly. These include:<p>
178 <li>Often targets include special or assembler linker flags which
179 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
180 just be removed.</li>
181 <li>LLVM currently does not support any floating point values other than
182 32-bit and 64-bit IEEE floating point. The primary effect of this is
183 that you may have to map "long double" onto "double".</li>
184 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
185 These may need to be disabled.</li>
186 <li>No inline assembly for position independent code. At the LLVM level,
187 everything is position independent.</li>
188 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
189 <li>You may have to disable multilib support in your target. Using multilib
190 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
191 options to the link line, which do not relate to LLVM and confuse
192 <tt>gccld</tt>. To disable multilibs, delete any
193 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
194 <li>Did we mention that we don't support inline assembly? You'll probably
195 have to add some fixinclude hacks to disable it in the system
200 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
201 the <code>--with-llvmgccdir=$CFEINSTALL</code> option to specify the path
202 to the newly built C front-end.</p></li>
204 <li><p>If you edited header files during the C/C++ front-end build as
205 described in "Fix 1" above, you must now copy those header files from
206 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
207 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
208 (This should be the "include" directory in the same directory as the
209 libgcc.a library, which you can find by running
210 <code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
212 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
213 rebuilt, but it should build the runtime libraries. After the tree is
214 built, install the runtime libraries into your C front-end build tree.
215 These are the commands you need.</p>
218 % mkdir $CFEINSTALL/bytecode-libs
219 % gmake -C runtime install-bytecode
220 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
223 <li><p>Test the newly-installed C frontend by one or more of the
226 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
227 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
228 test/Programs</code></li>
233 <!-- *********************************************************************** -->
234 <div class="doc_section">
235 <a name="license">License Information</a>
238 <div class="doc_text">
240 The LLVM GCC frontend is licensed to you under the GNU General Public License
241 and the GNU Lesser General Public License. Please see the files COPYING and
242 COPYING.LIB for more details.
246 The software also has the following additional copyrights:
251 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
258 University of Illinois at Urbana-Champaign
260 http://llvm.cs.uiuc.edu
262 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
263 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
264 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
265 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
266 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
267 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
271 Hewlett-Packard Company
273 Permission to use, copy, modify, distribute and sell this software
274 and its documentation for any purpose is hereby granted without fee,
275 provided that the above copyright notice appear in all copies and
276 that both that copyright notice and this permission notice appear
277 in supporting documentation. Hewlett-Packard Company makes no
278 representations about the suitability of this software for any
279 purpose. It is provided "as is" without express or implied warranty.
281 Copyright (c) 1996, 1997, 1998, 1999
282 Silicon Graphics Computer Systems, Inc.
284 Permission to use, copy, modify, distribute and sell this software
285 and its documentation for any purpose is hereby granted without fee,
286 provided that the above copyright notice appear in all copies and
287 that both that copyright notice and this permission notice appear
288 in supporting documentation. Silicon Graphics makes no
289 representations about the suitability of this software for any
290 purpose. It is provided "as is" without express or implied warranty.
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