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6 <title>Bootstrapping the LLVM C/C++ Front-End</title>
10 <div class="doc_title">
11 Bootstrapping the LLVM C/C++ Front-End
15 <li><a href="#cautionarynote">A Cautionary Note</a>
16 <li><a href="#instructions">Instructions</a>
17 <li><a href="#license">License Information</a>
20 <div class="doc_text">
21 <p><b>Written by Brian R. Gaeke</b></p>
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25 <div class="doc_section">
26 <a name="cautionarynote">A Cautionary Note</a>
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30 <div class="doc_text">
31 <p>This document is intended to explain the process of building the
32 LLVM C/C++ front-end, based on GCC 3.4, from its source code. You
33 would have to do this, for example, if you are porting LLVM to a new
34 architecture or operating system.</p>
36 <p><b>NOTE:</b> This is currently a somewhat fragile, error-prone
37 process, and you should <b>only</b> try to do it if:</p>
40 <li>you really, really, really can't use the binaries we distribute</li>
41 <li>you need GCC to fix some of the header files on your system</li>
42 <li>you are an elite GCC hacker.</li>
45 <p>We welcome patches to help make this process simpler.</p>
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49 <div class="doc_section">
50 <a name="instructions">Instructions</a>
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54 <div class="doc_text">
57 <li><p>Configure and build the LLVM libraries and tools using:</p>
60 % ./configure [options...]
63 <p>The use of the non-default target "tools-only" means that the
64 LLVM tools and libraries will build, and the binaries will be
65 deposited in llvm/tools/Debug, but the runtime (bytecode)
66 libraries will not build.</p></li>
68 <li><p>Add the directory containing the tools to your PATH.</p>
70 % set path = ( `cd llvm/tools/Debug && pwd` $path )
73 <li><p>Unpack the C/C++ front-end source into cfrontend/src.</p></li>
75 <li><p>Edit src/configure. Change the first line (starting w/ #!) to
76 contain the correct full pathname of sh.</p></li>
78 <li><p>Make "build" and "install" directories as siblings of the "src"
82 /usr/local/example/cfrontend/src
85 % set CFEINSTALL = `pwd`/install
88 <li><p>Configure, build, and install the C front-end:</p>
93 <b>MacOS X/PowerPC:</b>
98 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls --disable-shared \
99 --enable-languages=c,c++
101 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
102 % gmake all; gmake install
106 <b>Solaris/SPARC:</b>
110 For Solaris/SPARC, LLVM only supports the SPARC V9. Therefore, the
111 configure command line should specify sparcv9, as shown below. Also,
112 note that Solaris has trouble with various wide (multibyte) character
113 functions from C as referenced from C++, so we typically configure with
114 --disable-c-mbchar (cf. <a href="http://llvm.cs.uiuc.edu/PR206">Bug 206</a>).
119 % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \
120 --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \
123 % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc
124 % gmake all; gmake install
127 <p><b>Common Problem:</b> You may get error messages regarding the fact
128 that LLVM does not support inline assembly. Here are two common
132 <li><p><b>Fix 1:</b> If you have system header files that include
133 inline assembly, you may have to modify them to remove the inline
134 assembly, and install the modified versions in
135 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code>.</p></li>
137 <li><b>Fix 2:</b> If you are building the C++ front-end on a CPU we
138 haven't tried yet, you will probably have to edit the appropriate
139 version of atomicity.h under
140 <code>src/libstdc++-v3/config/cpu/<i>name-of-cpu</i>/atomicity.h</code>
141 and apply a patch so that it does not use inline assembly.</p></li>
144 <p><b>Porting to a new architecture:</b> If you are porting the new front-end
145 to a new architecture, or compiling in a different configuration that we have
146 previously, there are probably several changes you will have to make to the GCC
147 target to get it to work correctly. These include:<p>
150 <li>Often targets include special or assembler linker flags which
151 <tt>gccas</tt>/<tt>gccld</tt> does not understand. In general, these can
152 just be removed.</li>
153 <li>LLVM currently does not support any floating point values other than
154 32-bit and 64-bit IEEE floating point. The primary effect of this is
155 that you may have to map "long double" onto "double".</li>
156 <li>The profiling hooks in GCC do not apply at all to the LLVM front-end.
157 These may need to be disabled.</li>
158 <li>No inline assembly for position independent code. At the LLVM level,
159 everything is position independent.</li>
160 <li>We handle <tt>.init</tt> and <tt>.fini</tt> differently.</li>
161 <li>You may have to disable multilib support in your target. Using multilib
162 support causes the GCC compiler driver to add a lot of "<tt>-L</tt>"
163 options to the link line, which do not relate to LLVM and confuse
164 <tt>gccld</tt>. To disable multilibs, delete any
165 <tt>MULTILIB_OPTIONS</tt> lines from your target files.</li>
166 <li>Did we mention that we don't support inline assembly? You'll probably
167 have to add some fixinclude hacks to disable it in the system
172 <li><p>Go back into the LLVM source tree proper. Edit Makefile.config
173 to redefine <code>LLVMGCCDIR</code> to the full pathname of the
174 <code>$CFEINSTALL</code> directory, which is the directory you just
175 installed the C front-end into. (The ./configure script is likely to
176 have set this to a directory which does not exist on your system.)</p></li>
178 <li><p>If you edited header files during the C/C++ front-end build as
179 described in "Fix 1" above, you must now copy those header files from
180 <code>$CFEINSTALL/<i>target-triplet</i>/sys-include</code> to
181 <code>$CFEINSTALL/lib/gcc/<i>target-triplet</i>/3.4-llvm/include</code>.
182 (This should be the "include" directory in the same directory as the
183 libgcc.a library, which you can find by running
184 <code>$CFEINSTALL/bin/gcc --print-libgcc-file-name</code>.)</p></li>
186 <li><p>Build and install the runtime (bytecode) libraries by running:</p>
189 % mkdir $CFEINSTALL/bytecode-libs
190 % gmake -C runtime install-bytecode
191 % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
194 <li><p>Test the newly-installed C frontend by one or more of the
197 <li> compiling and running a "hello, LLVM" program in C and C++.</li>
198 <li> running the tests under <tt>test/Programs</tt> using <code>gmake -C
199 test/Programs</code></li>
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207 <div class="doc_section">
208 <a name="license">License Information</a>
211 <div class="doc_text">
213 The LLVM GCC frontend is licensed to you under the GNU General Public License
214 and the GNU Lesser General Public License. Please see the files COPYING and
215 COPYING.LIB for more details.
219 The software also has the following additional copyrights:
224 Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign.
231 University of Illinois at Urbana-Champaign
233 http://llvm.cs.uiuc.edu
235 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
236 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
237 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
238 CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
239 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
240 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
244 Hewlett-Packard Company
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252 purpose. It is provided "as is" without express or implied warranty.
254 Copyright (c) 1996, 1997, 1998, 1999
255 Silicon Graphics Computer Systems, Inc.
257 Permission to use, copy, modify, distribute and sell this software
258 and its documentation for any purpose is hereby granted without fee,
259 provided that the above copyright notice appear in all copies and
260 that both that copyright notice and this permission notice appear
261 in supporting documentation. Silicon Graphics makes no
262 representations about the suitability of this software for any
263 purpose. It is provided "as is" without express or implied warranty.
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271 <div class="doc_footer">
272 <address>Brian Gaeke</address>
273 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
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