Teach mergefunc that intptr_t is the same width as a pointer. We still can't
[llvm.git] / docs / GettingStarted.html
blob69510e85be6c434986a7727a03db23219426c323
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3 <html>
4 <head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <title>Getting Started with LLVM System</title>
7 <link rel="stylesheet" href="llvm.css" type="text/css">
8 </head>
9 <body>
11 <div class="doc_title">
12 Getting Started with the LLVM System
13 </div>
15 <ul>
16 <li><a href="#overview">Overview</a>
17 <li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
18 <li><a href="#requirements">Requirements</a>
19 <ol>
20 <li><a href="#hardware">Hardware</a></li>
21 <li><a href="#software">Software</a></li>
22 <li><a href="#brokengcc">Broken versions of GCC and other tools</a></li>
23 </ol></li>
25 <li><a href="#starting">Getting Started with LLVM</a>
26 <ol>
27 <li><a href="#terminology">Terminology and Notation</a></li>
28 <li><a href="#environment">Setting Up Your Environment</a></li>
29 <li><a href="#unpack">Unpacking the LLVM Archives</a></li>
30 <li><a href="#checkout">Checkout LLVM from Subversion</a></li>
31 <li><a href="#installcf">Install the GCC Front End</a></li>
32 <li><a href="#config">Local LLVM Configuration</a></li>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a></li>
34 <li><a href="#cross-compile">Cross-Compiling LLVM</a></li>
35 <li><a href="#objfiles">The Location of LLVM Object Files</a></li>
36 <li><a href="#optionalconfig">Optional Configuration Items</a></li>
37 </ol></li>
39 <li><a href="#layout">Program layout</a>
40 <ol>
41 <li><a href="#examples"><tt>llvm/examples</tt></a></li>
42 <li><a href="#include"><tt>llvm/include</tt></a></li>
43 <li><a href="#lib"><tt>llvm/lib</tt></a></li>
44 <li><a href="#projects"><tt>llvm/projects</tt></a></li>
45 <li><a href="#runtime"><tt>llvm/runtime</tt></a></li>
46 <li><a href="#test"><tt>llvm/test</tt></a></li>
47 <li><a href="#test-suite"><tt>test-suite</tt></a></li>
48 <li><a href="#tools"><tt>llvm/tools</tt></a></li>
49 <li><a href="#utils"><tt>llvm/utils</tt></a></li>
50 </ol></li>
52 <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
53 <ol>
54 <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
55 </ol>
56 <li><a href="#problems">Common Problems</a>
57 <li><a href="#links">Links</a>
58 </ul>
60 <div class="doc_author">
61 <p>Written by:
62 <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
63 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
64 <a href="http://misha.brukman.net">Misha Brukman</a>,
65 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
66 <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
67 </p>
68 </div>
71 <!-- *********************************************************************** -->
72 <div class="doc_section">
73 <a name="overview"><b>Overview</b></a>
74 </div>
75 <!-- *********************************************************************** -->
77 <div class="doc_text">
79 <p>Welcome to LLVM! In order to get started, you first need to know some
80 basic information.</p>
82 <p>First, LLVM comes in three pieces. The first piece is the LLVM
83 suite. This contains all of the tools, libraries, and header files
84 needed to use the low level virtual machine. It contains an
85 assembler, disassembler, bitcode analyzer and bitcode optimizer. It
86 also contains basic regression tests that can be used to test the LLVM
87 tools and the GCC front end.</p>
89 <p>The second piece is the GCC front end. This component provides a version of
90 GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front
91 end uses the GCC parser to convert code to LLVM. Once
92 compiled into LLVM bitcode, a program can be manipulated with the LLVM tools
93 from the LLVM suite.</p>
95 <p>
96 There is a third, optional piece called Test Suite. It is a suite of programs
97 with a testing harness that can be used to further test LLVM's functionality
98 and performance.
99 </p>
101 </div>
103 <!-- *********************************************************************** -->
104 <div class="doc_section">
105 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
106 </div>
107 <!-- *********************************************************************** -->
109 <div class="doc_text">
111 <p>Here's the short story for getting up and running quickly with LLVM:</p>
113 <ol>
114 <li>Read the documentation.</li>
115 <li>Read the documentation.</li>
116 <li>Remember that you were warned twice about reading the documentation.</li>
117 <li>Install the llvm-gcc-4.2 front end if you intend to compile C or C++
118 (see <a href="#installcf">Install the GCC Front End</a> for details):</li>
119 <ol>
120 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
121 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt></li>
122 <li><tt><i>install-binutils-binary-from-MinGW</i></tt> (Windows only)</li>
123 <li>Note: If the binary extension is "<tt>.bz</tt>" use <tt>bunzip2</tt> instead of <tt>gunzip</tt>.</li>
124 <li>Note: On Windows, use <a href="http://www.7-zip.org">7-Zip</a> or a similar archiving tool.</li>
125 <li>Add <tt>llvm-gcc</tt>'s "<tt>bin</tt>" directory to your <tt>PATH</tt> environment variable.</li>
126 </ol></li>
128 <li>Get the LLVM Source Code
129 <ul>
130 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
131 <ol>
132 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
133 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
134 </ol></li>
136 </ul></li>
138 <li><b>[Optional]</b> Get the Test Suite Source Code
139 <ul>
140 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
141 <ol>
142 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
143 <li><tt>cd llvm/projects</tt>
144 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
145 <li><tt>mv llvm-test-<i>version</i> test-suite</tt>
146 </ol></li>
148 </ul></li>
151 <li>Configure the LLVM Build Environment
152 <ol>
153 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
154 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
155 Some common options:
157 <ul>
158 <li><tt>--prefix=<i>directory</i></tt>
159 <p>Specify for <i>directory</i> the full pathname of where you
160 want the LLVM tools and libraries to be installed (default
161 <tt>/usr/local</tt>).</p></li>
162 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
163 <p>Optionally, specify for <i>directory</i> the full pathname of the
164 C/C++ front end installation to use with this LLVM configuration. If
165 not specified, the PATH will be searched. This is only needed if you
166 want to run test-suite or do some special kinds of LLVM builds.</p></li>
167 <li><tt>--enable-spec2000=<i>directory</i></tt>
168 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
169 benchmarks should be available in
170 <tt><i>directory</i></tt>.</p></li>
171 </ul>
172 </ol></li>
174 <li>Build the LLVM Suite:
175 <ol>
176 <li><tt>gmake -k |&amp; tee gnumake.out
177 &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
178 <li>If you get an "internal compiler error (ICE)" or test failures, see
179 <a href="#brokengcc">below</a>.</li>
180 </ol>
182 </ol>
184 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
185 detailed information on configuring and compiling LLVM. See <a
186 href="#environment">Setting Up Your Environment</a> for tips that simplify
187 working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
188 Layout</a> to learn about the layout of the source code tree.</p>
190 </div>
192 <!-- *********************************************************************** -->
193 <div class="doc_section">
194 <a name="requirements"><b>Requirements</b></a>
195 </div>
196 <!-- *********************************************************************** -->
198 <div class="doc_text">
200 <p>Before you begin to use the LLVM system, review the requirements given below.
201 This may save you some trouble by knowing ahead of time what hardware and
202 software you will need.</p>
204 </div>
206 <!-- ======================================================================= -->
207 <div class="doc_subsection">
208 <a name="hardware"><b>Hardware</b></a>
209 </div>
211 <div class="doc_text">
213 <p>LLVM is known to work on the following platforms:</p>
215 <table cellpadding="3" summary="Known LLVM platforms">
216 <tr>
217 <th>OS</th>
218 <th>Arch</th>
219 <th>Compilers</th>
220 </tr>
221 <tr>
222 <td>AuroraUX</td>
223 <td>x86<sup><a href="#pf_1">1</a></sup></td>
224 <td>GCC</td>
225 </tr>
226 <tr>
227 <td>Linux</td>
228 <td>x86<sup><a href="#pf_1">1</a></sup></td>
229 <td>GCC</td>
230 </tr>
231 <tr>
232 <td>Linux</td>
233 <td>amd64</td>
234 <td>GCC</td>
235 </tr>
236 <tr>
237 <td>Solaris</td>
238 <td>V9 (Ultrasparc)</td>
239 <td>GCC</td>
240 </tr>
241 <tr>
242 <td>FreeBSD</td>
243 <td>x86<sup><a href="#pf_1">1</a></sup></td>
244 <td>GCC</td>
245 </tr>
246 <tr>
247 <td>FreeBSD</td>
248 <td>amd64</td>
249 <td>GCC</td>
250 </tr>
251 <tr>
252 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
253 <td>PowerPC</td>
254 <td>GCC</td>
255 </tr>
256 <tr>
257 <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
258 <td>x86</td>
259 <td>GCC</td>
260 </tr>
261 <tr>
262 <td>Cygwin/Win32</td>
263 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a>,
264 <a href="#pf_11">11</a></sup></td>
265 <td>GCC 3.4.X, binutils 2.20</td>
266 </tr>
267 <tr>
268 <td>MinGW/Win32</td>
269 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,
270 <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td>
271 <td>GCC 3.4.X, binutils 2.20</td>
272 </tr>
273 </table>
275 <p>LLVM has partial support for the following platforms:</p>
277 <table summary="LLVM partial platform support">
278 <tr>
279 <th>OS</th>
280 <th>Arch</th>
281 <th>Compilers</th>
282 </tr>
283 <tr>
284 <td>Windows</td>
285 <td>x86<sup><a href="#pf_1">1</a></sup></td>
286 <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
287 <tr>
288 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
289 <td>PowerPC</td>
290 <td>GCC</td>
291 </tr>
292 <tr>
293 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
294 <td>PowerPC</td>
295 <td>GCC</td>
296 </tr>
298 <tr>
299 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
300 <td>Alpha</td>
301 <td>GCC</td>
302 </tr>
303 <tr>
304 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
305 <td>Itanium (IA-64)</td>
306 <td>GCC</td>
307 </tr>
308 <tr>
309 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
310 <td>Itanium (IA-64)</td>
311 <td>HP aCC</td>
312 </tr>
313 </table>
315 <p><b>Notes:</b></p>
317 <div class="doc_notes">
318 <ol>
319 <li><a name="pf_1">Code generation supported for Pentium processors and
320 up</a></li>
321 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
322 <li><a name="pf_3">No native code generation</a></li>
323 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
324 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
325 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
326 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
327 <li><a name="pf_8">Binutils 2.20 or later is required to build the assembler
328 generated by LLVM properly.</a></li>
329 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
330 internal LLVM assert messages when compiled for Release at optimization
331 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
332 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
333 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
334 <li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS
335 version of the perl package, and be sure it appears in your path
336 before any Windows-based versions such as Strawberry Perl and
337 ActivePerl, as these have Windows-specifics that will cause the
338 build to fail.</a></li>
339 <li><a name="pf_11">In general, LLVM modules requiring dynamic linking can
340 not be built on Windows. However, you can build LLVM tools using
341 <i>"make tools-only"</i>.</li>
342 </ol>
343 </div>
345 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
346 mode, depending on the system (it is so large because of all the debugging
347 information and the fact that the libraries are statically linked into multiple
348 tools). If you do not need many of the tools and you are space-conscious, you
349 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
350 requires considerably less space.</p>
352 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
353 guaranteed to do so. If compilation is successful, the LLVM utilities should be
354 able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
355 generation should work as well, although the generated native code may not work
356 on your platform.</p>
358 <p>The GCC front end is not very portable at the moment. If you want to get it
359 to work on another platform, you can download a copy of the source and <a
360 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
362 </div>
364 <!-- ======================================================================= -->
365 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
366 <div class="doc_text">
367 <p>Compiling LLVM requires that you have several software packages
368 installed. The table below lists those required packages. The Package column
369 is the usual name for the software package that LLVM depends on. The Version
370 column provides "known to work" versions of the package. The Notes column
371 describes how LLVM uses the package and provides other details.</p>
372 <table summary="Packages required to compile LLVM">
373 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
375 <tr>
376 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
377 <td>3.79, 3.79.1</td>
378 <td>Makefile/build processor</td>
379 </tr>
381 <tr>
382 <td><a href="http://gcc.gnu.org">GCC</a></td>
383 <td>3.4.2</td>
384 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
385 </tr>
387 <tr>
388 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
389 <td>4.5</td>
390 <td>For building the CFE</td>
391 </tr>
393 <tr>
394 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
395 <td>&ge;1.3</td>
396 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
397 </tr>
399 <tr>
400 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
401 <td>1.4.2</td>
402 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
403 </tr>
405 <tr>
406 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
407 <td>8.3, 8.4</td>
408 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
409 </tr>
411 <tr>
412 <td><a href="http://expect.nist.gov/">expect</a></td>
413 <td>5.38.0</td>
414 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
415 </tr>
417 <tr>
418 <td><a href="http://www.perl.com/download.csp">perl</a></td>
419 <td>&ge;5.6.0</td>
420 <td>Nightly tester, utilities</td>
421 </tr>
423 <tr>
424 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
425 <td>1.4</td>
426 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
427 </tr>
429 <tr>
430 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
431 <td>2.60</td>
432 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
433 </tr>
435 <tr>
436 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
437 <td>1.9.6</td>
438 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
439 </tr>
441 <tr>
442 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
443 <td>1.5.22</td>
444 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
445 </tr>
447 </table>
449 <p><b>Notes:</b></p>
450 <div class="doc_notes">
451 <ol>
452 <li><a name="sf1">Only the C and C++ languages are needed so there's no
453 need to build the other languages for LLVM's purposes.</a> See
454 <a href="#brokengcc">below</a> for specific version info.</li>
455 <li><a name="sf2">You only need Subversion if you intend to build from the
456 latest LLVM sources. If you're working from a release distribution, you
457 don't need Subversion.</a></li>
458 <li><a name="sf3">Only needed if you want to run the automated test
459 suite in the <tt>llvm/test</tt> directory.</a></li>
460 <li><a name="sf4">If you want to make changes to the configure scripts,
461 you will need GNU autoconf (2.60), and consequently, GNU M4 (version 1.4
462 or higher). You will also need automake (1.9.6). We only use aclocal
463 from that package.</a></li>
464 </ol>
465 </div>
467 <p>Additionally, your compilation host is expected to have the usual
468 plethora of Unix utilities. Specifically:</p>
469 <ul>
470 <li><b>ar</b> - archive library builder</li>
471 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
472 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
473 <li><b>chmod</b> - change permissions on a file</li>
474 <li><b>cat</b> - output concatenation utility</li>
475 <li><b>cp</b> - copy files</li>
476 <li><b>date</b> - print the current date/time </li>
477 <li><b>echo</b> - print to standard output</li>
478 <li><b>egrep</b> - extended regular expression search utility</li>
479 <li><b>find</b> - find files/dirs in a file system</li>
480 <li><b>grep</b> - regular expression search utility</li>
481 <li><b>gzip*</b> - gzip command for distribution generation</li>
482 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
483 <li><b>install</b> - install directories/files </li>
484 <li><b>mkdir</b> - create a directory</li>
485 <li><b>mv</b> - move (rename) files</li>
486 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
487 <li><b>rm</b> - remove (delete) files and directories</li>
488 <li><b>sed</b> - stream editor for transforming output</li>
489 <li><b>sh</b> - Bourne shell for make build scripts</li>
490 <li><b>tar</b> - tape archive for distribution generation</li>
491 <li><b>test</b> - test things in file system</li>
492 <li><b>unzip*</b> - unzip command for distribution checking</li>
493 <li><b>zip*</b> - zip command for distribution generation</li>
494 </ul>
495 </div>
497 <!-- ======================================================================= -->
498 <div class="doc_subsection">
499 <a name="brokengcc">Broken versions of GCC and other tools</a>
500 </div>
502 <div class="doc_text">
504 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
505 bugs in the compiler. In particular, several versions of GCC crash when trying
506 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
507 successfully with them (however, see important notes below). Other versions
508 of GCC will probably work as well. GCC versions listed
509 here are known to not work. If you are using one of these versions, please try
510 to upgrade your GCC to something more recent. If you run into a problem with a
511 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
512 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
513 of GCC you are using.
514 </p>
516 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
517 problems in the STL that effectively prevent it from compiling LLVM.
518 </p>
520 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
521 a bogus template error. This was fixed in later GCCs.</p>
523 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
524 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
525 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
527 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
528 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
529 to a newer version</a> if possible.</p>
530 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
531 possibly others) does not compile LLVM correctly (it appears that exception
532 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
533 to a newer version of GCC.</p>
534 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
535 code generator, causing an infinite loop in the llvm-gcc build when built
536 with optimizations enabled (i.e. a release build).</p>
537 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
538 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
539 correctly compiles LLVM at -O2. A work around is to build release LLVM
540 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
541 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
542 miscompiles portions of LLVM</a>.</p>
543 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
544 when building with optimizations enabled. It appears to work with
545 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
546 build.</p>
547 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
548 miscompile LLVM.</p>
549 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
550 default with ENABLE_OPTIMIZED=1. To work around this, build with
551 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
552 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
553 compiling some files. At the time of this writing, GCC mainline (4.2)
554 did not share the problem.</p>
555 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
556 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
557 code. LLVM will appear to mostly work but will be buggy, e.g. failing
558 portions of its testsuite.</p>
559 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
560 platforms compiling md5.c gets a mangled constant.</p>
561 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
562 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
563 about symbols remaining in the table on destruction.</p>
564 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
565 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
566 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
567 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
568 with link errors when using this GCC version.</p>
569 <p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p>
570 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
571 when optimizations are turned on. The symptom is an infinite loop in
572 FoldingSetImpl::RemoveNode while running the code generator.</p>
573 <p><b>GCC 4.3.5 and GCC 4.4.5 on ARM</b>: These can miscompile <tt>value >>
574 1</tt> even at -O0. A test failure in <tt>test/Assembler/alignstack.ll</tt> is
575 one symptom of the problem.
576 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
577 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
578 defined in a discarded section. You can safely ignore these messages as they are
579 erroneous and the linkage is correct. These messages disappear using ld
580 2.17.</p>
582 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
583 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
584 causes huge link times (minutes instead of seconds) when building LLVM. We
585 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
587 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
588 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
589 which causes intermittent failures when building LLVM with position independent
590 code. The symptom is an error about cyclic dependencies. We recommend
591 upgrading to a newer version of Gold.</p>
593 </div>
597 <!-- *********************************************************************** -->
598 <div class="doc_section">
599 <a name="starting"><b>Getting Started with LLVM</b></a>
600 </div>
601 <!-- *********************************************************************** -->
603 <div class="doc_text">
605 <p>The remainder of this guide is meant to get you up and running with
606 LLVM and to give you some basic information about the LLVM environment.</p>
608 <p>The later sections of this guide describe the <a
609 href="#layout">general layout</a> of the the LLVM source tree, a <a
610 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
611 href="#links">links</a> to find more information about LLVM or to get
612 help via e-mail.</p>
613 </div>
615 <!-- ======================================================================= -->
616 <div class="doc_subsection">
617 <a name="terminology">Terminology and Notation</a>
618 </div>
620 <div class="doc_text">
622 <p>Throughout this manual, the following names are used to denote paths
623 specific to the local system and working environment. <i>These are not
624 environment variables you need to set but just strings used in the rest
625 of this document below</i>. In any of the examples below, simply replace
626 each of these names with the appropriate pathname on your local system.
627 All these paths are absolute:</p>
629 <dl>
630 <dt>SRC_ROOT
631 <dd>
632 This is the top level directory of the LLVM source tree.
633 <br><br>
635 <dt>OBJ_ROOT
636 <dd>
637 This is the top level directory of the LLVM object tree (i.e. the
638 tree where object files and compiled programs will be placed. It
639 can be the same as SRC_ROOT).
640 <br><br>
642 <dt>LLVMGCCDIR
643 <dd>
644 This is where the LLVM GCC Front End is installed.
646 For the pre-built GCC front end binaries, the LLVMGCCDIR is
647 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
648 </dl>
650 </div>
652 <!-- ======================================================================= -->
653 <div class="doc_subsection">
654 <a name="environment">Setting Up Your Environment</a>
655 </div>
657 <div class="doc_text">
660 In order to compile and use LLVM, you may need to set some environment
661 variables.
663 <dl>
664 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
665 <dd>[Optional] This environment variable helps LLVM linking tools find the
666 locations of your bitcode libraries. It is provided only as a
667 convenience since you can specify the paths using the -L options of the
668 tools and the C/C++ front-end will automatically use the bitcode files
669 installed in its
670 <tt>lib</tt> directory.</dd>
671 </dl>
673 </div>
675 <!-- ======================================================================= -->
676 <div class="doc_subsection">
677 <a name="unpack">Unpacking the LLVM Archives</a>
678 </div>
680 <div class="doc_text">
683 If you have the LLVM distribution, you will need to unpack it before you
684 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
685 suite and the LLVM GCC front end compiled for your platform. There is an
686 additional test suite that is optional. Each file is a TAR archive that is
687 compressed with the gzip program.
688 </p>
690 <p>The files are as follows, with <em>x.y</em> marking the version number:
691 <dl>
692 <dt><tt>llvm-x.y.tar.gz</tt></dt>
693 <dd>Source release for the LLVM libraries and tools.<br></dd>
695 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
696 <dd>Source release for the LLVM test-suite.</dd>
698 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
699 <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
700 directory for build instructions.<br></dd>
702 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
703 <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
705 </dl>
707 </div>
709 <!-- ======================================================================= -->
710 <div class="doc_subsection">
711 <a name="checkout">Checkout LLVM from Subversion</a>
712 </div>
714 <div class="doc_text">
716 <p>If you have access to our Subversion repository, you can get a fresh copy of
717 the entire source code. All you need to do is check it out from Subversion as
718 follows:</p>
720 <ul>
721 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
722 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
723 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
724 llvm</tt></li>
725 </ul>
728 <p>This will create an '<tt>llvm</tt>' directory in the current
729 directory and fully populate it with the LLVM source code, Makefiles,
730 test directories, and local copies of documentation files.</p>
732 <p>If you want to get a specific release (as opposed to the most recent
733 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
734 '<tt>trunk</tt>'). The following releases are located in the following
735 subdirectories of the '<tt>tags</tt>' directory:</p>
737 <ul>
738 <li>Release 2.8: <b>RELEASE_28</b></li>
739 <li>Release 2.7: <b>RELEASE_27</b></li>
740 <li>Release 2.6: <b>RELEASE_26</b></li>
741 <li>Release 2.5: <b>RELEASE_25</b></li>
742 <li>Release 2.4: <b>RELEASE_24</b></li>
743 <li>Release 2.3: <b>RELEASE_23</b></li>
744 <li>Release 2.2: <b>RELEASE_22</b></li>
745 <li>Release 2.1: <b>RELEASE_21</b></li>
746 <li>Release 2.0: <b>RELEASE_20</b></li>
747 <li>Release 1.9: <b>RELEASE_19</b></li>
748 <li>Release 1.8: <b>RELEASE_18</b></li>
749 <li>Release 1.7: <b>RELEASE_17</b></li>
750 <li>Release 1.6: <b>RELEASE_16</b></li>
751 <li>Release 1.5: <b>RELEASE_15</b></li>
752 <li>Release 1.4: <b>RELEASE_14</b></li>
753 <li>Release 1.3: <b>RELEASE_13</b></li>
754 <li>Release 1.2: <b>RELEASE_12</b></li>
755 <li>Release 1.1: <b>RELEASE_11</b></li>
756 <li>Release 1.0: <b>RELEASE_1</b></li>
757 </ul>
759 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
760 you get it from the Subversion repository:</p>
762 <div class="doc_code">
763 <pre>
764 % cd llvm/projects
765 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite
766 </pre>
767 </div>
769 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
770 configured by the LLVM configure script as well as automatically updated when
771 you run <tt>svn update</tt>.</p>
773 <p>If you would like to get the GCC front end source code, you can also get it
774 and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
775 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
777 </div>
779 <!-- ======================================================================= -->
780 <div class="doc_subsection">
781 <a name="installcf">Install the GCC Front End</a>
782 </div>
784 <div class="doc_text">
786 <p>Before configuring and compiling the LLVM suite (or if you want to use just the LLVM
787 GCC front end) you can optionally extract the front end from the binary distribution.
788 It is used for running the LLVM test-suite and for compiling C/C++ programs. Note that
789 you can optionally <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
790 main LLVM repository.</p>
792 <p>To install the GCC front end, do the following (on Windows, use an archival tool
793 like <a href="http://www.7-zip.org">7-zip</a> that understands gzipped tars):</p>
795 <ol>
796 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
797 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
798 -</tt></li>
799 </ol>
801 <p>Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for
802 <tt>llvm-gcc</tt> and <tt>llvm-g++</tt> to some directory in your path. If you're using a
803 Windows-based system, add the <tt>bin</tt> subdirectory of your front end installation directory
804 to your <tt>PATH</tt> environment variable. For example, if you uncompressed the binary to
805 <tt>c:\llvm-gcc</tt>, add <tt>c:\llvm-gcc\bin</tt> to your <tt>PATH</tt>.</p>
807 <p>If you now want to build LLVM from source, when you configure LLVM, it will
808 automatically detect <tt>llvm-gcc</tt>'s presence (if it is in your path) enabling its
809 use in test-suite. Note that you can always build or install <tt>llvm-gcc</tt> at any
810 point after building the main LLVM repository: just reconfigure llvm and
811 test-suite will pick it up.
812 </p>
814 <p>As a convenience for Windows users, the front end binaries for MinGW/x86 include
815 versions of the required w32api and mingw-runtime binaries. The last remaining step for
816 Windows users is to simply uncompress the binary binutils package from
817 <a href="http://mingw.org/">MinGW</a> into your front end installation directory. While the
818 front end installation steps are not quite the same as a typical manual MinGW installation,
819 they should be similar enough to those who have previously installed MinGW on Windows systems.</p>
821 <p>To install binutils on Windows:</p>
823 <ol>
824 <li><tt><i>download GNU Binutils from <a href="http://sourceforge.net/projects/mingw/files/">MinGW Downloads</a></i></tt></li>
825 <li><tt>cd <i>where-you-uncompressed-the-front-end</i></tt></li>
826 <li><tt><i>uncompress archived binutils directories (not the tar file) into the current directory</i></tt></li>
827 </ol>
829 <p>The binary versions of the LLVM GCC front end may not suit all of your needs. For
830 example, the binary distribution may include an old version of a system header
831 file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with
832 libraries not available on your system. In cases like these, you may want to try
833 <a href="GCCFEBuildInstrs.html">building the GCC front end from source</a>. Thankfully,
834 this is much easier now than it was in the past.</p>
836 <p>We also do not currently support updating of the GCC front end by manually overlaying
837 newer versions of the w32api and mingw-runtime binary packages that may become available
838 from MinGW. At this time, it's best to think of the MinGW LLVM GCC front end binary as
839 a self-contained convenience package that requires Windows users to simply download and
840 uncompress the GNU Binutils binary package from the MinGW project.</p>
842 <p>Regardless of your platform, if you discover that installing the LLVM GCC front end
843 binaries is not as easy as previously described, or you would like to suggest improvements,
844 please let us know how you would like to see things improved by dropping us a note on our
845 <a href="http://llvm.org/docs/#maillist">mailing list</a>.</p>
847 </div>
849 <!-- ======================================================================= -->
850 <div class="doc_subsection">
851 <a name="config">Local LLVM Configuration</a>
852 </div>
854 <div class="doc_text">
856 <p>Once checked out from the Subversion repository, the LLVM suite source
857 code must be
858 configured via the <tt>configure</tt> script. This script sets variables in the
859 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
860 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
861 the Makefiles needed to begin building LLVM.</p>
863 <p>The following environment variables are used by the <tt>configure</tt>
864 script to configure the build system:</p>
866 <table summary="LLVM configure script environment variables">
867 <tr><th>Variable</th><th>Purpose</th></tr>
868 <tr>
869 <td>CC</td>
870 <td>Tells <tt>configure</tt> which C compiler to use. By default,
871 <tt>configure</tt> will look for the first GCC C compiler in
872 <tt>PATH</tt>. Use this variable to override
873 <tt>configure</tt>'s default behavior.</td>
874 </tr>
875 <tr>
876 <td>CXX</td>
877 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
878 <tt>configure</tt> will look for the first GCC C++ compiler in
879 <tt>PATH</tt>. Use this variable to override
880 <tt>configure</tt>'s default behavior.</td>
881 </tr>
882 </table>
884 <p>The following options can be used to set or enable LLVM specific options:</p>
886 <dl>
887 <dt><i>--with-llvmgccdir</i></dt>
888 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
889 The value of this option should specify the full pathname of the C/C++ Front
890 End to be used. If this option is not provided, the PATH will be searched for
891 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
892 be inferred from the path found. If the option is not given, and no llvm-gcc
893 can be found in the path then a warning will be produced by
894 <tt>configure</tt> indicating this situation. LLVM may still be built with
895 the <tt>tools-only</tt> target but attempting to build the runtime libraries
896 will fail as these libraries require llvm-gcc and llvm-g++. See
897 <a href="#installcf">Install the GCC Front End</a> for details on installing
898 the C/C++ Front End. See
899 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
900 for details on building the C/C++ Front End.</dd>
901 <dt><i>--with-tclinclude</i></dt>
902 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
903 found. Use this if you have multiple tcl installations on your machine and you
904 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
905 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
906 option, the LLVM configure script will search for the tcl 8.4 and 8.3
907 releases.
908 <br><br>
909 </dd>
910 <dt><i>--enable-optimized</i></dt>
911 <dd>
912 Enables optimized compilation (debugging symbols are removed
913 and GCC optimization flags are enabled). Note that this is the default
914 setting if you are using the LLVM distribution. The default behavior
915 of an Subversion checkout is to use an unoptimized build (also known as a
916 debug build).
917 <br><br>
918 </dd>
919 <dt><i>--enable-debug-runtime</i></dt>
920 <dd>
921 Enables debug symbols in the runtime libraries. The default is to strip
922 debug symbols from the runtime libraries.
923 </dd>
924 <dt><i>--enable-jit</i></dt>
925 <dd>
926 Compile the Just In Time (JIT) compiler functionality. This is not
927 available
928 on all platforms. The default is dependent on platform, so it is best
929 to explicitly enable it if you want it.
930 <br><br>
931 </dd>
932 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
933 <dd>Controls which targets will be built and linked into llc. The default
934 value for <tt>target_options</tt> is "all" which builds and links all
935 available targets. The value "host-only" can be specified to build only a
936 native compiler (no cross-compiler targets available). The "native" target is
937 selected as the target of the build host. You can also specify a comma
938 separated list of target names that you want available in llc. The target
939 names use all lower case. The current set of targets is: <br>
940 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
941 <br><br></dd>
942 <dt><i>--enable-doxygen</i></dt>
943 <dd>Look for the doxygen program and enable construction of doxygen based
944 documentation from the source code. This is disabled by default because
945 generating the documentation can take a long time and producess 100s of
946 megabytes of output.</dd>
947 <dt><i>--with-udis86</i></dt>
948 <dd>LLVM can use external disassembler library for various purposes (now it's
949 used only for examining code produced by JIT). This option will enable usage
950 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
951 bits) disassembler library.</dd>
952 </dl>
954 <p>To configure LLVM, follow these steps:</p>
956 <ol>
957 <li><p>Change directory into the object root directory:</p>
959 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
961 <li><p>Run the <tt>configure</tt> script located in the LLVM source
962 tree:</p>
964 <div class="doc_code">
965 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
966 </div></li>
967 </ol>
969 </div>
971 <!-- ======================================================================= -->
972 <div class="doc_subsection">
973 <a name="compile">Compiling the LLVM Suite Source Code</a>
974 </div>
976 <div class="doc_text">
978 <p>Once you have configured LLVM, you can build it. There are three types of
979 builds:</p>
981 <dl>
982 <dt>Debug Builds
983 <dd>
984 These builds are the default when one is using an Subversion checkout and
985 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
986 used during configuration). The build system will compile the tools and
987 libraries with debugging information. To get a Debug Build using the
988 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
989 to <tt>configure</tt>.
990 <br><br>
992 <dt>Release (Optimized) Builds
993 <dd>
994 These builds are enabled with the <tt>--enable-optimized</tt> option to
995 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
996 <tt>gmake</tt> command line. For these builds, the build system will
997 compile the tools and libraries with GCC optimizations enabled and strip
998 debugging information from the libraries and executables it generates.
999 Note that Release Builds are default when using an LLVM distribution.
1000 <br><br>
1002 <dt>Profile Builds
1003 <dd>
1004 These builds are for use with profiling. They compile profiling
1005 information into the code for use with programs like <tt>gprof</tt>.
1006 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
1007 on the <tt>gmake</tt> command line.
1008 </dl>
1010 <p>Once you have LLVM configured, you can build it by entering the
1011 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
1013 <div class="doc_code"><pre>% gmake</pre></div>
1015 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
1016 are using a version of GCC that is known not to compile LLVM.</p>
1019 If you have multiple processors in your machine, you may wish to use some of
1020 the parallel build options provided by GNU Make. For example, you could use the
1021 command:</p>
1023 <div class="doc_code"><pre>% gmake -j2</pre></div>
1025 <p>There are several special targets which are useful when working with the LLVM
1026 source code:</p>
1028 <dl>
1029 <dt><tt>gmake clean</tt>
1030 <dd>
1031 Removes all files generated by the build. This includes object files,
1032 generated C/C++ files, libraries, and executables.
1033 <br><br>
1035 <dt><tt>gmake dist-clean</tt>
1036 <dd>
1037 Removes everything that <tt>gmake clean</tt> does, but also removes files
1038 generated by <tt>configure</tt>. It attempts to return the source tree to the
1039 original state in which it was shipped.
1040 <br><br>
1042 <dt><tt>gmake install</tt>
1043 <dd>
1044 Installs LLVM header files, libraries, tools, and documentation in a
1045 hierarchy
1046 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
1047 defaults to <tt>/usr/local</tt>.
1048 <br><br>
1050 <dt><tt>gmake -C runtime install-bytecode</tt>
1051 <dd>
1052 Assuming you built LLVM into $OBJDIR, when this command is run, it will
1053 install bitcode libraries into the GCC front end's bitcode library
1054 directory. If you need to update your bitcode libraries,
1055 this is the target to use once you've built them.
1056 <br><br>
1057 </dl>
1059 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1060 details on these <tt>make</tt> targets and descriptions of other targets
1061 available.</p>
1063 <p>It is also possible to override default values from <tt>configure</tt> by
1064 declaring variables on the command line. The following are some examples:</p>
1066 <dl>
1067 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1068 <dd>
1069 Perform a Release (Optimized) build.
1070 <br><br>
1072 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1073 <dd>
1074 Perform a Release (Optimized) build without assertions enabled.
1075 <br><br>
1077 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1078 <dd>
1079 Perform a Debug build.
1080 <br><br>
1082 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1083 <dd>
1084 Perform a Profiling build.
1085 <br><br>
1087 <dt><tt>gmake VERBOSE=1</tt>
1088 <dd>
1089 Print what <tt>gmake</tt> is doing on standard output.
1090 <br><br>
1092 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1093 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1094 the standard output. This also implies <tt>VERBOSE=1</tt>.
1095 <br><br></dd>
1096 </dl>
1098 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1099 it and any subdirectories that it contains. Entering any directory inside the
1100 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1101 that directory that is out of date.</p>
1103 </div>
1105 <!-- ======================================================================= -->
1106 <div class="doc_subsection">
1107 <a name="cross-compile">Cross-Compiling LLVM</a>
1108 </div>
1110 <div class="doc_text">
1111 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1112 executables and libraries to be hosted on a platform different from the
1113 platform where they are build (a Canadian Cross build). To configure a
1114 cross-compile, supply the configure script with <tt>--build</tt> and
1115 <tt>--host</tt> options that are different. The values of these options must
1116 be legal target triples that your GCC compiler supports.</p>
1118 <p>The result of such a build is executables that are not runnable on
1119 on the build host (--build option) but can be executed on the compile host
1120 (--host option).</p>
1121 </div>
1123 <!-- ======================================================================= -->
1124 <div class="doc_subsection">
1125 <a name="objfiles">The Location of LLVM Object Files</a>
1126 </div>
1128 <div class="doc_text">
1130 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1131 several LLVM builds. Hence, it is possible to build LLVM for several different
1132 platforms or configurations using the same source tree.</p>
1134 <p>This is accomplished in the typical autoconf manner:</p>
1136 <ul>
1137 <li><p>Change directory to where the LLVM object files should live:</p>
1139 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1141 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1142 directory:</p>
1144 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1145 </ul>
1147 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1148 named after the build type:</p>
1150 <dl>
1151 <dt>Debug Builds with assertions enabled (the default)
1152 <dd>
1153 <dl>
1154 <dt>Tools
1155 <dd><tt><i>OBJ_ROOT</i>/Debug+Asserts/bin</tt>
1156 <dt>Libraries
1157 <dd><tt><i>OBJ_ROOT</i>/Debug+Asserts/lib</tt>
1158 </dl>
1159 <br><br>
1161 <dt>Release Builds
1162 <dd>
1163 <dl>
1164 <dt>Tools
1165 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1166 <dt>Libraries
1167 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1168 </dl>
1169 <br><br>
1171 <dt>Profile Builds
1172 <dd>
1173 <dl>
1174 <dt>Tools
1175 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1176 <dt>Libraries
1177 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1178 </dl>
1179 </dl>
1181 </div>
1183 <!-- ======================================================================= -->
1184 <div class="doc_subsection">
1185 <a name="optionalconfig">Optional Configuration Items</a>
1186 </div>
1188 <div class="doc_text">
1191 If you're running on a Linux system that supports the "<a
1192 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1193 module, and you have root access on the system, you can set your system up to
1194 execute LLVM bitcode files directly. To do this, use commands like this (the
1195 first command may not be required if you are already using the module):</p>
1197 <div class="doc_code">
1198 <pre>
1199 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1200 $ echo ':llvm:M::BC::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1201 $ chmod u+x hello.bc (if needed)
1202 $ ./hello.bc
1203 </pre>
1204 </div>
1207 This allows you to execute LLVM bitcode files directly. On Debian, you
1208 can also use this command instead of the 'echo' command above:</p>
1209 </p>
1211 <div class="doc_code">
1212 <pre>
1213 $ sudo update-binfmts --install llvm /path/to/lli --magic 'BC'
1214 </pre>
1215 </div>
1217 </div>
1219 <!-- *********************************************************************** -->
1220 <div class="doc_section">
1221 <a name="layout"><b>Program Layout</b></a>
1222 </div>
1223 <!-- *********************************************************************** -->
1225 <div class="doc_text">
1227 <p>One useful source of information about the LLVM source base is the LLVM <a
1228 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1229 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1230 The following is a brief introduction to code layout:</p>
1232 </div>
1234 <!-- ======================================================================= -->
1235 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1236 <div class="doc_text">
1237 <p>This directory contains some simple examples of how to use the LLVM IR and
1238 JIT.</p>
1239 </div>
1241 <!-- ======================================================================= -->
1242 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1243 <div class="doc_text">
1245 <p>This directory contains public header files exported from the LLVM
1246 library. The three main subdirectories of this directory are:</p>
1248 <dl>
1249 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1250 <dd>This directory contains all of the LLVM specific header files. This
1251 directory also has subdirectories for different portions of LLVM:
1252 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1253 etc...</dd>
1255 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1256 <dd>This directory contains generic support libraries that are provided with
1257 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1258 and a Command Line option processing library store their header files here.
1259 </dd>
1261 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1262 <dd>This directory contains header files configured by the <tt>configure</tt>
1263 script. They wrap "standard" UNIX and C header files. Source code can
1264 include these header files which automatically take care of the conditional
1265 #includes that the <tt>configure</tt> script generates.</dd>
1266 </dl>
1267 </div>
1269 <!-- ======================================================================= -->
1270 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1271 <div class="doc_text">
1273 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1274 almost all code exists in libraries, making it very easy to share code among the
1275 different <a href="#tools">tools</a>.</p>
1277 <dl>
1278 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1279 <dd> This directory holds the core LLVM source files that implement core
1280 classes like Instruction and BasicBlock.</dd>
1282 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1283 <dd>This directory holds the source code for the LLVM assembly language parser
1284 library.</dd>
1286 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1287 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1289 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1290 different program analyses, such as Dominator Information, Call Graphs,
1291 Induction Variables, Interval Identification, Natural Loop Identification,
1292 etc.</dd>
1294 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1295 <dd> This directory contains the source code for the LLVM to LLVM program
1296 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1297 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1298 Elimination, and many others.</dd>
1300 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1301 <dd> This directory contains files that describe various target architectures
1302 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1303 directory holds the X86 machine description while
1304 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1306 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1307 <dd> This directory contains the major parts of the code generator: Instruction
1308 Selector, Instruction Scheduling, and Register Allocation.</dd>
1310 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1311 <dd> This directory contains the source level debugger library that makes
1312 it possible to instrument LLVM programs so that a debugger could identify
1313 source code locations at which the program is executing.</dd>
1315 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1316 <dd> This directory contains libraries for executing LLVM bitcode directly
1317 at runtime in both interpreted and JIT compiled fashions.</dd>
1319 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1320 <dd> This directory contains the source code that corresponds to the header
1321 files located in <tt>llvm/include/Support/</tt>.</dd>
1323 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1324 <dd>This directory contains the operating system abstraction layer that
1325 shields LLVM from platform-specific coding.</dd>
1326 </dl>
1328 </div>
1330 <!-- ======================================================================= -->
1331 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1332 <div class="doc_text">
1333 <p>This directory contains projects that are not strictly part of LLVM but are
1334 shipped with LLVM. This is also the directory where you should create your own
1335 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1336 to set up your own project.</p>
1337 </div>
1339 <!-- ======================================================================= -->
1340 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1341 <div class="doc_text">
1343 <p>This directory contains libraries which are compiled into LLVM bitcode and
1344 used when linking programs with the GCC front end. Most of these libraries are
1345 skeleton versions of real libraries; for example, libc is a stripped down
1346 version of glibc.</p>
1348 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1349 end to compile.</p>
1351 </div>
1353 <!-- ======================================================================= -->
1354 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1355 <div class="doc_text">
1356 <p>This directory contains feature and regression tests and other basic sanity
1357 checks on the LLVM infrastructure. These are intended to run quickly and cover
1358 a lot of territory without being exhaustive.</p>
1359 </div>
1361 <!-- ======================================================================= -->
1362 <div class="doc_subsection"><a name="test-suite"><tt>test-suite</tt></a></div>
1363 <div class="doc_text">
1364 <p>This is not a directory in the normal llvm module; it is a separate
1365 Subversion
1366 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1367 This
1368 module contains a comprehensive correctness, performance, and benchmarking
1369 test
1370 suite for LLVM. It is a separate Subversion module because not every LLVM
1371 user is
1372 interested in downloading or building such a comprehensive test suite. For
1373 further details on this test suite, please see the
1374 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1375 </div>
1377 <!-- ======================================================================= -->
1378 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1379 <div class="doc_text">
1381 <p>The <b>tools</b> directory contains the executables built out of the
1382 libraries above, which form the main part of the user interface. You can
1383 always get help for a tool by typing <tt>tool_name -help</tt>. The
1384 following is a brief introduction to the most important tools. More detailed
1385 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1387 <dl>
1389 <dt><tt><b>bugpoint</b></tt></dt>
1390 <dd><tt>bugpoint</tt> is used to debug
1391 optimization passes or code generation backends by narrowing down the
1392 given test case to the minimum number of passes and/or instructions that
1393 still cause a problem, whether it is a crash or miscompilation. See <a
1394 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1395 on using <tt>bugpoint</tt>.</dd>
1397 <dt><tt><b>llvmc</b></tt></dt>
1398 <dd>The LLVM Compiler Driver. This program can
1399 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1400 pre-processing, translation, optimization, assembly, and linking of programs
1401 all from one command line. <tt>llvmc</tt> also takes care of processing the
1402 dependent libraries found in bitcode. This reduces the need to get the
1403 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1404 note that this tool, while functional, is still experimental and not feature
1405 complete.</dd>
1407 <dt><tt><b>llvm-ar</b></tt></dt>
1408 <dd>The archiver produces an archive containing
1409 the given LLVM bitcode files, optionally with an index for faster
1410 lookup.</dd>
1412 <dt><tt><b>llvm-as</b></tt></dt>
1413 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1414 bitcode.</dd>
1416 <dt><tt><b>llvm-dis</b></tt></dt>
1417 <dd>The disassembler transforms the LLVM bitcode to human readable
1418 LLVM assembly.</dd>
1420 <dt><tt><b>llvm-ld</b></tt></dt>
1421 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1422 This is the linker invoked by <tt>llvmc</tt>. It performs standard link time
1423 optimizations and allows optimization modules to be loaded and run so that
1424 language specific optimizations can be applied at link time.</dd>
1426 <dt><tt><b>llvm-link</b></tt></dt>
1427 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1428 a single program.</dd>
1430 <dt><tt><b>lli</b></tt></dt>
1431 <dd><tt>lli</tt> is the LLVM interpreter, which
1432 can directly execute LLVM bitcode (although very slowly...). For architectures
1433 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1434 will function as a Just-In-Time compiler (if the functionality was compiled
1435 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1437 <dt><tt><b>llc</b></tt></dt>
1438 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1439 translates LLVM bitcode to a native code assembly file or to C code (with
1440 the -march=c option).</dd>
1442 <dt><tt><b>llvm-gcc</b></tt></dt>
1443 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1444 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1445 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1446 usual machine code output. It works just like any other GCC compiler,
1447 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1448 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1449 separate Subversion module.</dd>
1451 <dt><tt><b>opt</b></tt></dt>
1452 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1453 transformations (which are specified on the command line), and then outputs
1454 the resultant bitcode. The '<tt>opt -help</tt>' command is a good way to
1455 get a list of the program transformations available in LLVM.<br>
1456 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1457 LLVM bitcode file and print out the results. It is primarily useful for
1458 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1459 </dl>
1460 </div>
1462 <!-- ======================================================================= -->
1463 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1464 <div class="doc_text">
1466 <p>This directory contains utilities for working with LLVM source code, and some
1467 of the utilities are actually required as part of the build process because they
1468 are code generators for parts of LLVM infrastructure.</p>
1470 <dl>
1471 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1472 that finds differences between code that LLC generates and code that LLI
1473 generates. This is a useful tool if you are debugging one of them,
1474 assuming that the other generates correct output. For the full user
1475 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1477 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1478 syntax-highlighting files which will work with Emacs and XEmacs editors,
1479 providing syntax highlighting support for LLVM assembly files and TableGen
1480 description files. For information on how to use the syntax files, consult
1481 the <tt>README</tt> file in that directory.<br><br>
1483 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1484 and outputs all non-generated source files, which is useful if one wishes
1485 to do a lot of development across directories and does not want to
1486 individually find each file. One way to use it is to run, for example:
1487 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1488 tree.<br><br>
1490 <dt><tt><b>llvmgrep</b></tt></dt>
1491 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1492 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1493 line. This is a very efficient way of searching the source base for a
1494 particular regular expression.</dd>
1496 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1497 files in the current directory and then compiles and links the tool that
1498 is the first argument. For example, assuming you are in the directory
1499 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1500 simply running <tt>makellvm llc</tt> will make a build of the current
1501 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1502 causing a re-linking of LLC.<br><br>
1504 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1505 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1506 cron script to generate nightly status reports of the functionality of
1507 tools, and the results can be seen by following the appropriate link on
1508 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1510 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1511 the tool used to generate register descriptions, instruction set
1512 descriptions, and even assemblers from common TableGen description
1513 files.<br><br>
1515 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1516 syntax-highlighting files which will work with the VIM editor, providing
1517 syntax highlighting support for LLVM assembly files and TableGen
1518 description files. For information on how to use the syntax files, consult
1519 the <tt>README</tt> file in that directory.<br><br>
1521 </dl>
1523 </div>
1525 <!-- *********************************************************************** -->
1526 <div class="doc_section">
1527 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1528 </div>
1529 <!-- *********************************************************************** -->
1531 <div class="doc_text">
1532 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1533 so we only include instructions for llvm-gcc4.
1534 </p>
1536 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1537 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1538 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1539 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1540 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1541 output.</p>
1542 </div>
1544 <!-- ======================================================================= -->
1545 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1547 <div class="doc_text">
1549 <ol>
1550 <li><p>First, create a simple C file, name it 'hello.c':</p>
1552 <div class="doc_code">
1553 <pre>
1554 #include &lt;stdio.h&gt;
1556 int main() {
1557 printf("hello world\n");
1558 return 0;
1560 </pre></div></li>
1562 <li><p>Next, compile the C file into a native executable:</p>
1564 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1566 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1567 -c arguments work as usual (producing a native .s or .o file,
1568 respectively).</p></li>
1570 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1572 <div class="doc_code">
1573 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1575 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1576 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1577 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1578 the bitcode file.</p>
1580 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1581 </p></li>
1583 <li><p>Run the program in both forms. To run the program, use:</p>
1585 <div class="doc_code"><pre>% ./hello</pre></div>
1587 <p>and</p>
1589 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1591 <p>The second examples shows how to invoke the LLVM JIT, <a
1592 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1594 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1595 code:</p>
1597 <div class="doc_code">
1598 <pre>llvm-dis &lt; hello.bc | less</pre>
1599 </div></li>
1601 <li><p>Compile the program to native assembly using the LLC code
1602 generator:</p>
1604 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1606 <li><p>Assemble the native assembly language file into a program:</p>
1608 <div class="doc_code">
1609 <pre>
1610 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1612 <b>Others:</b> % gcc hello.s -o hello.native
1613 </pre>
1614 </div></li>
1616 <li><p>Execute the native code program:</p>
1618 <div class="doc_code"><pre>% ./hello.native</pre></div>
1620 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1621 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1622 </li>
1624 </ol>
1626 </div>
1629 <!-- *********************************************************************** -->
1630 <div class="doc_section">
1631 <a name="problems">Common Problems</a>
1632 </div>
1633 <!-- *********************************************************************** -->
1635 <div class="doc_text">
1637 <p>If you are having problems building or using LLVM, or if you have any other
1638 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1639 Asked Questions</a> page.</p>
1641 </div>
1643 <!-- *********************************************************************** -->
1644 <div class="doc_section">
1645 <a name="links">Links</a>
1646 </div>
1647 <!-- *********************************************************************** -->
1649 <div class="doc_text">
1651 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1652 some simple things... there are many more interesting and complicated things
1653 that you can do that aren't documented here (but we'll gladly accept a patch
1654 if you want to write something up!). For more information about LLVM, check
1655 out:</p>
1657 <ul>
1658 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1659 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1660 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1661 that Uses LLVM</a></li>
1662 </ul>
1664 </div>
1666 <!-- *********************************************************************** -->
1668 <hr>
1669 <address>
1670 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1671 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
1672 <a href="http://validator.w3.org/check/referer"><img
1673 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
1675 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1676 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1677 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1678 Last modified: $Date$
1679 </address>
1680 </body>
1681 </html>