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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 need GCC to fix some of the header files on your system</li>
49 <li>you are an elite GCC hacker.</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 C 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.
72 <!--=========================================================================-->
73 <div class="doc_subsection">
74 <a name="aix">Building under AIX</a>
76 <!--=========================================================================-->
78 <div class="doc_text">
79 <p>If you are building LLVM and the C front-end under AIX, do NOT use GNU
80 Binutils. They are not stable under AIX and may produce incorrect and/or
81 invalid code. Instead, use the system assembler and linker.
85 <!-- *********************************************************************** -->
86 <div class="doc_section">
87 <a name="instructions">Instructions</a>
89 <!-- *********************************************************************** -->
91 <div class="doc_text">
94 <li><p>Configure and build the LLVM libraries and tools using:</p>
97 % ./configure [options...]
100 <p>This will build all of the LLVM tools and libraries.</p></li>
102 <li><p>Add the directory containing the tools to your PATH.</p>
104 % set path = ( `cd llvm/tools/Debug && pwd` $path )
107 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
109 <li><p>Make "build" and "install" directories as siblings of the "src" tree.</p>
112 /usr/local/example/cfrontend/src
114 % mkdir build install
115 % set CFEINSTALL = `pwd`/install
119 <li><p>Configure, build, and install the C front-end:</p>
122 <b>Linux/x86:</b><br>
123 <b>MacOS X/PowerPC</b> (requires dlcompat library):<br>
129 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
130 --disable-shared --enable-languages=c,c++
132 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
133 % gmake all; gmake install
136 <p><b>Cygwin/x86:</b></p>
140 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
141 --disable-shared --enable-languages=c,c++ --disable-c-mbchar
143 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
144 % gmake all; gmake install
147 <p><b>Solaris/SPARC:</b></p>
150 For Solaris/SPARC, LLVM only supports the SPARC V9 architecture. Therefore,
151 the configure command line should specify sparcv9, as shown below. Also,
152 note that Solaris has trouble with various wide (multibyte) character
153 functions from C as referenced from C++, so we typically configure with
154 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
159 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
160 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
163 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
164 % gmake all; gmake install
167 <p><b>Common Problem:</b> You may get error messages regarding the fact
168 that LLVM does not support inline assembly. Here are two common
172 <li><p><b>Fix 1:</b> If you have system header files that include
173 inline assembly, you may have to modify them to remove the inline
174 assembly, and install the modified versions in
175 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.</li>
177 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
178 haven't tried yet, you will probably have to edit the appropriate
179 version of atomicity.h under
180 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
181 and apply a patch so that it does not use inline assembly.</li>
184 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
185 to a new architecture, or compiling in a different configuration that we have
186 previously, there are probably several changes you will have to make to the GCC
187 target to get it to work correctly. These include:<p>
190 <li>Often targets include special assembler or linker flags which
191 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
192 just be removed.</li>
193 <li>LLVM currently does not support any floating point values other than
194 32-bit and 64-bit IEEE floating point. The primary effect of this is
195 that you may have to map "long double" onto "double".</li>
196 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
197 These may need to be disabled.</li>
198 <li>No inline assembly for position independent code. At the LLVM level,
199 everything is position independent.</li>
200 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
201 <li>You may have to disable multilib support in your target. Using multilib
202 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
203 options to the link line, which do not relate to LLVM and confuse
204 <tt>gccld</tt>. To disable multilibs, delete any
205 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
206 <li>Did we mention that we don't support inline assembly? You'll probably
207 have to add some fixinclude hacks to disable it in the system
212 <li><p>Go back into the LLVM source tree proper. Rerun configure, using
213 the <code>--with-llvmgccdir=$CFEINSTALL</code> option to specify the path
214 to the newly built C front-end.</p></li>
216 <li><p>If you edited header files during the C/C++ front-end build as
217 described in "Fix 1" above, you must now copy those header files from
218 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
219 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
220 (This should be the "include" directory in the same directory as the
221 libgcc.a library, which you can find by running
222 <code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
224 <li><p>Rebuild your CVS tree. This shouldn't cause the whole thing to be
225 rebuilt, but it should build the runtime libraries. After the tree is
226 built, install the runtime libraries into your C front-end build tree.
227 These are the commands you need.</p>
230 % mkdir $CFEINSTALL/bytecode-libs
231 % gmake -C runtime install
232 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
235 <li><p>Optionally, build a symbol table for the newly installed runtime
236 libraries. Although this step is optional, you are encouraged to do this as the
237 symbol tables will make a significant difference in your link times. Use
238 the <tt>llvm-ranlib</tt> tool to do this, as follows:</p>
241 % llvm-ranlib libiberty.a
242 % llvm-ranlib libstdc++.a
243 % llvm-ranlib libsubc++.a
244 % cd $CFEINSTALL/lib/<i>target-triplet</i>/3.4-llvm
245 % llvm-ranlib libgcc.a
246 % llvm-ranlib libgcov.a
249 <li><p>Test the newly-installed C frontend by one or more of the
252 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
253 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
254 test/Programs</code></li>
259 <!-- *********************************************************************** -->
260 <div class="doc_section">
261 <a name="license">License Information</a>
264 <div class="doc_text">
266 The LLVM GCC frontend is licensed to you under the GNU General Public License
267 and the GNU Lesser General Public License. Please see the files COPYING and
268 COPYING.LIB for more details.
272 The software also has the following additional copyrights:
277 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
284 University of Illinois at Urbana-Champaign
286 http://llvm.cs.uiuc.edu
288 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
289 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
290 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
291 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
292 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
293 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
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299 Permission to use, copy, modify, distribute and sell this software
300 and its documentation for any purpose is hereby granted without fee,
301 provided that the above copyright notice appear in all copies and
302 that both that copyright notice and this permission notice appear
303 in supporting documentation. Hewlett-Packard Company makes no
304 representations about the suitability of this software for any
305 purpose. It is provided "as is" without express or implied warranty.
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308 Silicon Graphics Computer Systems, Inc.
310 Permission to use, copy, modify, distribute and sell this software
311 and its documentation for any purpose is hereby granted without fee,
312 provided that the above copyright notice appear in all copies and
313 that both that copyright notice and this permission notice appear
314 in supporting documentation. Silicon Graphics makes no
315 representations about the suitability of this software for any
316 purpose. It is provided "as is" without express or implied warranty.
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