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6 <title>Getting Started with LLVM System</title>
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9<body>
10
11<div class="doc_title">
12 Getting Started with the LLVM System
13</div>
14
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>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]23 </ol></li>
24
25 <li><a href="#starting">Getting Started with LLVM</a>
26 <ol>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]37 </ol></li>
38
39 <li><a href="#layout">Program layout</a>
40 <ol>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]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="#llvmtest"><tt>llvm-test</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 <li><a href="#win32"><tt>llvm/win32</tt></a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]51 </ol></li>
52
53 <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
54 <ol>
55 <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
56 </ol>
57 <li><a href="#problems">Common Problems</a>
58 <li><a href="#links">Links</a>
59</ul>
60
61<div class="doc_author">
62 <p>Written by:
63 <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
64 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
65 <a href="http://misha.brukman.net">Misha Brukman</a>,
66 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
67 <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
68 </p>
69</div>
70
71
72<!-- *********************************************************************** -->
73<div class="doc_section">
74 <a name="overview"><b>Overview</b></a>
75</div>
76<!-- *********************************************************************** -->
77
78<div class="doc_text">
79
80<p>Welcome to LLVM! In order to get started, you first need to know some
81basic information.</p>
82
83<p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
84contains all of the tools, libraries, and header files needed to use the low
85level virtual machine. It contains an assembler, disassembler, bitcode
86analyzer and bitcode optimizer. It also contains a test suite that can be
87used to test the LLVM tools and the GCC front end.</p>
88
89<p>The second piece is the GCC front end. This component provides a version of
90GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front
91end uses the GCC parser to convert code to LLVM. Once
92compiled into LLVM bitcode, a program can be manipulated with the LLVM tools
93from the LLVM suite.</p>
94
95<p>
96There is a third, optional piece called llvm-test. It is a suite of programs
97with a testing harness that can be used to further test LLVM's functionality
98and performance.
99</p>
100
101</div>
102
103<!-- *********************************************************************** -->
104<div class="doc_section">
105 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
106</div>
107<!-- *********************************************************************** -->
108
109<div class="doc_text">
110
111<p>Here's the short story for getting up and running quickly with LLVM:</p>
112
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>
Tanya Lattner99c4a2c2007-09-27 18:14:33 +0000[diff] [blame]117 <li>Install the llvm-gcc4.0 (or llvm-gcc4.2) front end if you intend to compile C or C++:
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]118 <ol>
119 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
120 <li><tt>gunzip --stdout llvm-gcc.<i>platform</i>.tar.gz | tar -xvf -</tt>
121 </li>
Tanya Lattner99c4a2c2007-09-27 18:14:33 +0000[diff] [blame]122 <ul><li>If the binary extension is ".bz" use bunzip2 instead of gunzip.</li>
123 </ul>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]124 <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
125 </ol></li>
126
127 <li>Get the LLVM Source Code
128 <ul>
129 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
130 <ol>
131 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
132 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
133 </ol></li>
134
135 </ul></li>
136
137 <li><b>[Optional]</b> Get the Test Suite Source Code
138 <ul>
139 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
140 <ol>
141 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
142 <li><tt>cd llvm/projects</tt>
143 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
144 </ol></li>
145
146 </ul></li>
147
148
149 <li>Configure the LLVM Build Environment
150 <ol>
151 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
152 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
153 Some common options:
154
155 <ul>
156 <li><tt>--prefix=<i>directory</i></tt>
157 <p>Specify for <i>directory</i> the full pathname of where you
158 want the LLVM tools and libraries to be installed (default
159 <tt>/usr/local</tt>).</p></li>
160 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
161 <p>Optionally, specify for <i>directory</i> the full pathname of the
162 C/C++ front end installation to use with this LLVM configuration. If
163 not specified, the PATH will be searched.</p></li>
164 <li><tt>--enable-spec2000=<i>directory</i></tt>
165 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
166 benchmarks should be available in
167 <tt><i>directory</i></tt>.</p></li>
168 </ul>
169 </ol></li>
170
171 <li>Build the LLVM Suite:
172 <ol>
173 <li><tt>gmake -k |&amp; tee gnumake.out
174 &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
175 <li>If you get an "internal compiler error (ICE)" or test failures, see
176 <a href="#brokengcc">below</a>.</li>
177 </ol>
178
179</ol>
180
181<p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
182detailed information on configuring and compiling LLVM. See <a
183href="#environment">Setting Up Your Environment</a> for tips that simplify
184working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
185Layout</a> to learn about the layout of the source code tree.</p>
186
187</div>
188
189<!-- *********************************************************************** -->
190<div class="doc_section">
191 <a name="requirements"><b>Requirements</b></a>
192</div>
193<!-- *********************************************************************** -->
194
195<div class="doc_text">
196
197<p>Before you begin to use the LLVM system, review the requirements given below.
198This may save you some trouble by knowing ahead of time what hardware and
199software you will need.</p>
200
201</div>
202
203<!-- ======================================================================= -->
204<div class="doc_subsection">
205 <a name="hardware"><b>Hardware</b></a>
206</div>
207
208<div class="doc_text">
209
210<p>LLVM is known to work on the following platforms:</p>
211
212<table cellpadding="3" summary="Known LLVM platforms">
213<tr>
214 <th>OS</th>
215 <th>Arch</th>
216 <th>Compilers</th>
217</tr>
218<tr>
219 <td>Linux</td>
220 <td>x86<sup><a href="#pf_1">1</a></sup></td>
221 <td>GCC</td>
222</tr>
223<tr>
224 <td>Solaris</td>
225 <td>V9 (Ultrasparc)</td>
226 <td>GCC</td>
227</tr>
228<tr>
229 <td>FreeBSD</td>
230 <td>x86<sup><a href="#pf_1">1</a></sup></td>
231 <td>GCC</td>
232</tr>
233<tr>
234 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
235 <td>PowerPC</td>
236 <td>GCC</td>
237</tr>
238<tr>
239 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
240 <td>x86</td>
241 <td>GCC</td>
242
243</tr>
244<tr>
245 <td>Cygwin/Win32</td>
246 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
247 <td>GCC 3.4.X, binutils 2.15</td>
248</tr>
249<tr>
250 <td>MinGW/Win32</td>
251 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
252 <td>GCC 3.4.X, binutils 2.15</td>
253</tr>
254<tr>
255 <td>Linux</td>
256 <td>amd64<sup><a href="#pf_3">3</a></sup></td>
257 <td>GCC</td>
258</tr>
259</table>
260
261<p>LLVM has partial support for the following platforms:</p>
262
263<table summary="LLVM partial platform support">
264<tr>
265 <th>OS</th>
266 <th>Arch</th>
267 <th>Compilers</th>
268</tr>
269<tr>
270 <td>Windows</td>
271 <td>x86<sup><a href="#pf_1">1</a></sup></td>
272 <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
273<tr>
274 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
275 <td>PowerPC</td>
276 <td>GCC</td>
277</tr>
278<tr>
279 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
280 <td>PowerPC</td>
281 <td>GCC</td>
282</tr>
283
284<tr>
285 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
286 <td>Alpha</td>
287 <td>GCC</td>
288</tr>
289<tr>
290 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
291 <td>Itanium (IA-64)</td>
292 <td>GCC</td>
293</tr>
294<tr>
295 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
296 <td>Itanium (IA-64)</td>
297 <td>HP aCC</td>
298</tr>
299</table>
300
301<p><b>Notes:</b></p>
302
303<div class="doc_notes">
304<ol>
305<li><a name="pf_1">Code generation supported for Pentium processors and
306up</a></li>
307<li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
308<li><a name="pf_3">No native code generation</a></li>
309<li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
310<li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
311<li><a name="pf_6">The port is done using the MSYS shell.</a>
312<a href="http://www.mingw.org/MinGWiki/">Download</a> and install
313bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
314if necessary. Bison &amp; flex can be also grabbed from GNUWin32 sf.net
315project.</li>
316<li><a name="pf_7">Native code generation exists but is not complete.</a></li>
317<li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
318 preventing LLVM from building correctly. Several workarounds have been
319 introduced into LLVM build system, but the bug can occur anytime in the
320 future. We highly recommend that you rebuild your current binutils with the
321 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
322 Binutils bugzilla</a>, if it wasn't already applied.</li>
323</ol>
324</div>
325
326<p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
327mode, depending on the system (it is so large because of all the debugging
328information and the fact that the libraries are statically linked into multiple
329tools). If you do not need many of the tools and you are space-conscious,
330you can disable them individually in <tt>llvm/tools/Makefile</tt>. The Release
331build requires considerably less space.</p>
332
333<p>The LLVM suite <i>may</i> compile on other platforms, but it is not
334guaranteed to do so. If compilation is successful, the LLVM utilities should be
335able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
336generation should work as well, although the generated native code may not work
337on your platform.</p>
338
339<p>The GCC front end is not very portable at the moment. If you want to get it
340to work on another platform, you can download a copy of the source and <a
341href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
342
343</div>
344
345<!-- ======================================================================= -->
346<div class="doc_subsection"><a name="software"><b>Software</b></a></div>
347<div class="doc_text">
348 <p>Compiling LLVM requires that you have several software packages
349 installed. The table below lists those required packages. The Package column
350 is the usual name for the software package that LLVM depends on. The Version
351 column provides "known to work" versions of the package. The Notes column
352 describes how LLVM uses the package and provides other details.</p>
353 <table summary="Packages required to compile LLVM">
354 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
355
356 <tr>
357 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
358 <td>3.79, 3.79.1</td>
359 <td>Makefile/build processor</td>
360 </tr>
361
362 <tr>
363 <td><a href="http://gcc.gnu.org">GCC</a></td>
364 <td>3.4.2</td>
365 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
366 </tr>
367
368 <tr>
369 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
370 <td>4.5</td>
371 <td>For building the CFE</td>
372 </tr>
373
374 <tr>
375 <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
376 <td>2.5.4</td>
377 <td>LEX compiler</td>
378 </tr>
379
380 <tr>
381 <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
382 <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
383 <td>YACC compiler</td>
384 </tr>
385
386 <tr>
387 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
388 <td>&ge;1.3</td>
389 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
390 </tr>
391
392 <tr>
393 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
394 <td>1.4.2</td>
395 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
396 </tr>
397
398 <tr>
399 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
400 <td>8.3, 8.4</td>
401 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
402 </tr>
403
404 <tr>
405 <td><a href="http://expect.nist.gov/">expect</a></td>
406 <td>5.38.0</td>
407 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
408 </tr>
409
410 <tr>
411 <td><a href="http://www.perl.com/download.csp">perl</a></td>
412 <td>&ge;5.6.0</td>
413 <td>Nightly tester, utilities</td>
414 </tr>
415
416 <tr>
417 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
418 <td>1.4</td>
419 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
420 </tr>
421
422 <tr>
423 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
424 <td>2.59</td>
425 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
426 </tr>
427
428 <tr>
429 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
430 <td>1.9.2</td>
431 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
432 </tr>
433
434 <tr>
435 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
436 <td>1.5.10</td>
437 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
438 </tr>
439
440 </table>
441
442 <p><b>Notes:</b></p>
443 <div class="doc_notes">
444 <ol>
445 <li><a name="sf1">Only the C and C++ languages are needed so there's no
446 need to build the other languages for LLVM's purposes.</a> See
447 <a href="#brokengcc">below</a> for specific version info.</li>
448 <li><a name="sf2">You only need Subversion if you intend to build from the
449 latest LLVM sources. If you're working from a release distribution, you
450 don't need Subversion.</a></li>
451 <li><a name="sf3">Only needed if you want to run the automated test
452 suite in the <tt>llvm/test</tt> directory.</a></li>
453 <li><a name="sf4">If you want to make changes to the configure scripts,
454 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
455 or higher). You will also need automake (1.9.2). We only use aclocal
456 from that package.</a></li>
457 </ol>
458 </div>
459
460 <p>Additionally, your compilation host is expected to have the usual
461 plethora of Unix utilities. Specifically:</p>
462 <ul>
463 <li><b>ar</b> - archive library builder</li>
464 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
465 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
466 <li><b>chmod</b> - change permissions on a file</li>
467 <li><b>cat</b> - output concatenation utility</li>
468 <li><b>cp</b> - copy files</li>
469 <li><b>date</b> - print the current date/time </li>
470 <li><b>echo</b> - print to standard output</li>
471 <li><b>egrep</b> - extended regular expression search utility</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]472 <li><b>find</b> - find files/dirs in a file system</li>
473 <li><b>grep</b> - regular expression search utility</li>
474 <li><b>gzip*</b> - gzip command for distribution generation</li>
475 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
476 <li><b>install</b> - install directories/files </li>
477 <li><b>mkdir</b> - create a directory</li>
478 <li><b>mv</b> - move (rename) files</li>
479 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
480 <li><b>rm</b> - remove (delete) files and directories</li>
481 <li><b>sed</b> - stream editor for transforming output</li>
482 <li><b>sh</b> - Bourne shell for make build scripts</li>
483 <li><b>tar</b> - tape archive for distribution generation</li>
484 <li><b>test</b> - test things in file system</li>
485 <li><b>unzip*</b> - unzip command for distribution checking</li>
486 <li><b>zip*</b> - zip command for distribution generation</li>
487 </ul>
488</div>
489
490<!-- ======================================================================= -->
491<div class="doc_subsection">
492 <a name="brokengcc">Broken versions of GCC and other tools</a>
493</div>
494
495<div class="doc_text">
496
497<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
498bugs in the compiler. In particular, several versions of GCC crash when trying
499to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
500successfully with them (however, see important notes below). Other versions
501of GCC will probably work as well. GCC versions listed
502here are known to not work. If you are using one of these versions, please try
503to upgrade your GCC to something more recent. If you run into a problem with a
504version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
505us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
506of GCC you are using.
507</p>
508
509<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
510problems in the STL that effectively prevent it from compiling LLVM.
511</p>
512
513<p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
514
515<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
516href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
517the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
518
519<p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
520 Cygwin does not work. Please <a href="CFEBuildInstrs.html#cygwin">upgrade
521 to a newer version</a> if possible.</p>
522<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
523 possibly others) does not compile LLVM correctly (it appears that exception
524 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
525 to a newer version of GCC.</p>
526<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
527 code generator, causing an infinite loop in the llvm-gcc build when built
528 with optimizations enabled (i.e. a release build).</p>
529<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
530 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
531 correctly compiles LLVM at -O2. A work around is to build release LLVM
532 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
533<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
534 miscompiles portions of LLVM</a>.</p>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]535<p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
536 when building with optimizations enabled. It appears to work with
537 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
538 build.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]539<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
540 miscompile LLVM.</p>
541<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
542 default with ENABLE_OPTIMIZED=1. To work around this, build with
543 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
544<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
545 compiling some files. At the time of this writing, GCC mainline (4.2)
546 did not share the problem.</p>
547<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
548 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
549 code. LLVM will appear to mostly work but will be buggy, e.g. failing
550 portions of its testsuite.</p>
551<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
552platforms compiling md5.c gets a mangled constant.</p>
553<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
554long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
555defined in a discarded section. You can safely ignore these messages as they are
556erroneous and the linkage is correct. These messages disappear using ld
5572.17.</p>
558
559<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
560href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
561causes huge link times (minutes instead of seconds) when building LLVM. We
562recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
563
564</div>
565
566
567
568<!-- *********************************************************************** -->
569<div class="doc_section">
570 <a name="starting"><b>Getting Started with LLVM</b></a>
571</div>
572<!-- *********************************************************************** -->
573
574<div class="doc_text">
575
576<p>The remainder of this guide is meant to get you up and running with
577LLVM and to give you some basic information about the LLVM environment.</p>
578
579<p>The later sections of this guide describe the <a
580href="#layout">general layout</a> of the the LLVM source tree, a <a
581href="#tutorial">simple example</a> using the LLVM tool chain, and <a
582href="#links">links</a> to find more information about LLVM or to get
583help via e-mail.</p>
584</div>
585
586<!-- ======================================================================= -->
587<div class="doc_subsection">
588 <a name="terminology">Terminology and Notation</a>
589</div>
590
591<div class="doc_text">
592
593<p>Throughout this manual, the following names are used to denote paths
594specific to the local system and working environment. <i>These are not
595environment variables you need to set but just strings used in the rest
596of this document below</i>. In any of the examples below, simply replace
597each of these names with the appropriate pathname on your local system.
598All these paths are absolute:</p>
599
600<dl>
601 <dt>SRC_ROOT
602 <dd>
603 This is the top level directory of the LLVM source tree.
604 <br><br>
605
606 <dt>OBJ_ROOT
607 <dd>
608 This is the top level directory of the LLVM object tree (i.e. the
609 tree where object files and compiled programs will be placed. It
610 can be the same as SRC_ROOT).
611 <br><br>
612
613 <dt>LLVMGCCDIR
614 <dd>
615 This is where the LLVM GCC Front End is installed.
616 <p>
617 For the pre-built GCC front end binaries, the LLVMGCCDIR is
618 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
619</dl>
620
621</div>
622
623<!-- ======================================================================= -->
624<div class="doc_subsection">
625 <a name="environment">Setting Up Your Environment</a>
626</div>
627
628<div class="doc_text">
629
630<p>
631In order to compile and use LLVM, you may need to set some environment
632variables.
633
634<dl>
635 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
636 <dd>[Optional] This environment variable helps LLVM linking tools find the
637 locations of your bitcode libraries. It is provided only as a
638 convenience since you can specify the paths using the -L options of the
639 tools and the C/C++ front-end will automatically use the bitcode files
640 installed in its
641 <tt>lib</tt> directory.</dd>
642</dl>
643
644</div>
645
646<!-- ======================================================================= -->
647<div class="doc_subsection">
648 <a name="unpack">Unpacking the LLVM Archives</a>
649</div>
650
651<div class="doc_text">
652
653<p>
654If you have the LLVM distribution, you will need to unpack it before you
655can begin to compile it. LLVM is distributed as a set of two files: the LLVM
656suite and the LLVM GCC front end compiled for your platform. There is an
657additional test suite that is optional. Each file is a TAR archive that is
658compressed with the gzip program.
659</p>
660
661<p>The files are as follows, with <em>x.y</em> marking the version number:
662<dl>
663 <dt><tt>llvm-x.y.tar.gz</tt></dt>
664 <dd>Source release for the LLVM libraries and tools.<br/></dd>
665
666 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
667 <dd>Source release for the LLVM test suite.</dd>
668
669 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
670 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
671 directory for build instructions.<br/></dd>
672
673 <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
674 <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
675
676</dl>
677
678<p>It is also possible to download the sources of the llvm-gcc4 front end from a
679read-only subversion mirror at
680svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
681
682</div>
683
684<!-- ======================================================================= -->
685<div class="doc_subsection">
686 <a name="checkout">Checkout LLVM from Subversion</a>
687</div>
688
689<div class="doc_text">
690
691<p>If you have access to our Subversion repository, you can get a fresh copy of
692the entire source code. All you need to do is check it out from Subvresion as
693follows:</p>
694
695<ul>
696 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
697 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
698 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
699 llvm</tt></li>
700</ul>
701
702
703<p>This will create an '<tt>llvm</tt>' directory in the current
704directory and fully populate it with the LLVM source code, Makefiles,
705test directories, and local copies of documentation files.</p>
706
707<p>If you want to get a specific release (as opposed to the most recent
708revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
709'<tt>trunk</tt>'). The following releases are located in the following
710 subdirectories of the '<tt>tags</tt>' directory:</p>
711
712<ul>
Tanya Lattner2fad5b02007-09-28 22:50:54 +0000[diff] [blame]713<li>Release 2.1: <b>RELEASE_21</b></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]714<li>Release 2.0: <b>RELEASE_20</b></li>
715<li>Release 1.9: <b>RELEASE_19</b></li>
716<li>Release 1.8: <b>RELEASE_18</b></li>
717<li>Release 1.7: <b>RELEASE_17</b></li>
718<li>Release 1.6: <b>RELEASE_16</b></li>
719<li>Release 1.5: <b>RELEASE_15</b></li>
720<li>Release 1.4: <b>RELEASE_14</b></li>
721<li>Release 1.3: <b>RELEASE_13</b></li>
722<li>Release 1.2: <b>RELEASE_12</b></li>
723<li>Release 1.1: <b>RELEASE_11</b></li>
724<li>Release 1.0: <b>RELEASE_1</b></li>
725</ul>
726
727<p>If you would like to get the LLVM test suite (a separate package as of 1.4),
728you get it from the Subversion repository:</p>
729
730<div class="doc_code">
731<pre>
732% cd llvm/projects
733% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
734</pre>
735</div>
736
737<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
738configured by the LLVM configure script as well as automatically updated when
739you run <tt>svn update</tt>.</p>
740
741<p>If you would like to get the GCC front end source code, you can also get it
742and build it yourself. Please follow <a href="CFEBuildInstrs.html">these
743instructions</a> to successfully get and build the LLVM GCC front-end.</p>
744
745</div>
746
747<!-- ======================================================================= -->
748<div class="doc_subsection">
749 <a name="installcf">Install the GCC Front End</a>
750</div>
751
752<div class="doc_text">
753
754<p>Before configuring and compiling the LLVM suite, you can optionally extract the
755LLVM GCC front end from the binary distribution. It is used for running the
756llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
757<a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
758main LLVM repository.</p>
759
760<p>To install the GCC front end, do the following:</p>
761
762<ol>
763 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
764 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
765 -</tt></li>
766</ol>
767
768<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
769llvm-g++ to some directory in your path. When you configure LLVM, it will
770automatically detect llvm-gcc's presence (if it is in your path) enabling its
771use in llvm-test. Note that you can always build or install llvm-gcc at any
772pointer after building the main LLVM repository: just reconfigure llvm and
773llvm-test will pick it up.
774</p>
775
776<p>The binary versions of the GCC front end may not suit all of your needs. For
777example, the binary distribution may include an old version of a system header
778file, not "fix" a header file that needs to be fixed for GCC, or it may be
779linked with libraries not available on your system.</p>
780
781<p>In cases like these, you may want to try <a
782href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
783much easier now than it was in the past.</p>
784
785</div>
786
787<!-- ======================================================================= -->
788<div class="doc_subsection">
789 <a name="config">Local LLVM Configuration</a>
790</div>
791
792<div class="doc_text">
793
794 <p>Once checked out from the Subversion repository, the LLVM suite source
795 code must be
796configured via the <tt>configure</tt> script. This script sets variables in the
797various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
798<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
799the Makefiles needed to begin building LLVM.</p>
800
801<p>The following environment variables are used by the <tt>configure</tt>
802script to configure the build system:</p>
803
804<table summary="LLVM configure script environment variables">
805 <tr><th>Variable</th><th>Purpose</th></tr>
806 <tr>
807 <td>CC</td>
808 <td>Tells <tt>configure</tt> which C compiler to use. By default,
809 <tt>configure</tt> will look for the first GCC C compiler in
810 <tt>PATH</tt>. Use this variable to override
811 <tt>configure</tt>'s default behavior.</td>
812 </tr>
813 <tr>
814 <td>CXX</td>
815 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
816 <tt>configure</tt> will look for the first GCC C++ compiler in
817 <tt>PATH</tt>. Use this variable to override
818 <tt>configure</tt>'s default behavior.</td>
819 </tr>
820</table>
821
822<p>The following options can be used to set or enable LLVM specific options:</p>
823
824<dl>
825 <dt><i>--with-llvmgccdir</i></dt>
826 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
827 The value of this option should specify the full pathname of the C/C++ Front
828 End to be used. If this option is not provided, the PATH will be searched for
829 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
830 be inferred from the path found. If the option is not given, and no llvm-gcc
831 can be found in the path then a warning will be produced by
832 <tt>configure</tt> indicating this situation. LLVM may still be built with
833 the <tt>tools-only</tt> target but attempting to build the runtime libraries
834 will fail as these libraries require llvm-gcc and llvm-g++. See
835 <a href="#installcf">Install the GCC Front End</a> for details on installing
836 the C/C++ Front End. See
837 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
838 for details on building the C/C++ Front End.</dd>
839 <dt><i>--with-tclinclude</i></dt>
840 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
841 found. Use this if you have multiple tcl installations on your machine and you
842 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
843 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
844 option, the LLVM configure script will search for the tcl 8.4 and 8.3
845 releases.
846 <br><br>
847 </dd>
848 <dt><i>--enable-optimized</i></dt>
849 <dd>
850 Enables optimized compilation by default (debugging symbols are removed
851 and GCC optimization flags are enabled). The default is to use an
852 unoptimized build (also known as a debug build).
853 <br><br>
854 </dd>
855 <dt><i>--enable-debug-runtime</i></dt>
856 <dd>
857 Enables debug symbols in the runtime libraries. The default is to strip
858 debug symbols from the runtime libraries.
859 </dd>
860 <dt><i>--enable-jit</i></dt>
861 <dd>
862 Compile the Just In Time (JIT) compiler functionality. This is not
863 available
864 on all platforms. The default is dependent on platform, so it is best
865 to explicitly enable it if you want it.
866 <br><br>
867 </dd>
868 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
869 <dd>Controls which targets will be built and linked into llc. The default
870 value for <tt>target_options</tt> is "all" which builds and links all
871 available targets. The value "host-only" can be specified to build only a
872 native compiler (no cross-compiler targets available). The "native" target is
873 selected as the target of the build host. You can also specify a comma
874 separated list of target names that you want available in llc. The target
875 names use all lower case. The current set of targets is: <br/>
876 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
877 <br><br></dd>
878 <dt><i>--enable-doxygen</i></dt>
879 <dd>Look for the doxygen program and enable construction of doxygen based
880 documentation from the source code. This is disabled by default because
881 generating the documentation can take a long time and producess 100s of
882 megabytes of output.</dd>
883 <dt><i>--with-udis86</i></dt>
884 <dd>LLVM can use external disassembler library for various purposes (now it's
885 used only for examining code produced by JIT). This option will enable usage
886 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
887 bits) disassembler library.</dd>
888</dl>
889
890<p>To configure LLVM, follow these steps:</p>
891
892<ol>
893 <li><p>Change directory into the object root directory:</p>
894
895 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
896
897 <li><p>Run the <tt>configure</tt> script located in the LLVM source
898 tree:</p>
899
900 <div class="doc_code">
901 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
902 </div></li>
903</ol>
904
905</div>
906
907<!-- ======================================================================= -->
908<div class="doc_subsection">
909 <a name="compile">Compiling the LLVM Suite Source Code</a>
910</div>
911
912<div class="doc_text">
913
914<p>Once you have configured LLVM, you can build it. There are three types of
915builds:</p>
916
917<dl>
918 <dt>Debug Builds
919 <dd>
920 These builds are the default when one types <tt>gmake</tt> (unless the
921 <tt>--enable-optimized</tt> option was used during configuration). The
922 build system will compile the tools and libraries with debugging
923 information.
924 <br><br>
925
926 <dt>Release (Optimized) Builds
927 <dd>
928 These builds are enabled with the <tt>--enable-optimized</tt> option to
929 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
930 <tt>gmake</tt> command line. For these builds, the build system will
931 compile the tools and libraries with GCC optimizations enabled and strip
932 debugging information from the libraries and executables it generates.
933 <br><br>
934
935 <dt>Profile Builds
936 <dd>
937 These builds are for use with profiling. They compile profiling
938 information into the code for use with programs like <tt>gprof</tt>.
939 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
940 on the <tt>gmake</tt> command line.
941</dl>
942
943<p>Once you have LLVM configured, you can build it by entering the
944<i>OBJ_ROOT</i> directory and issuing the following command:</p>
945
946<div class="doc_code"><pre>% gmake</pre></div>
947
948<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
949are using a version of GCC that is known not to compile LLVM.</p>
950
951<p>
952If you have multiple processors in your machine, you may wish to use some of
953the parallel build options provided by GNU Make. For example, you could use the
954command:</p>
955
956<div class="doc_code"><pre>% gmake -j2</pre></div>
957
958<p>There are several special targets which are useful when working with the LLVM
959source code:</p>
960
961<dl>
962 <dt><tt>gmake clean</tt>
963 <dd>
964 Removes all files generated by the build. This includes object files,
965 generated C/C++ files, libraries, and executables.
966 <br><br>
967
968 <dt><tt>gmake dist-clean</tt>
969 <dd>
970 Removes everything that <tt>gmake clean</tt> does, but also removes files
971 generated by <tt>configure</tt>. It attempts to return the source tree to the
972 original state in which it was shipped.
973 <br><br>
974
975 <dt><tt>gmake install</tt>
976 <dd>
977 Installs LLVM header files, libraries, tools, and documentation in a
978 hierarchy
979 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
980 defaults to <tt>/usr/local</tt>.
981 <br><br>
982
983 <dt><tt>gmake -C runtime install-bytecode</tt>
984 <dd>
985 Assuming you built LLVM into $OBJDIR, when this command is run, it will
986 install bitcode libraries into the GCC front end's bitcode library
987 directory. If you need to update your bitcode libraries,
988 this is the target to use once you've built them.
989 <br><br>
990</dl>
991
992<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
993details on these <tt>make</tt> targets and descriptions of other targets
994available.</p>
995
996<p>It is also possible to override default values from <tt>configure</tt> by
997declaring variables on the command line. The following are some examples:</p>
998
999<dl>
1000 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1001 <dd>
1002 Perform a Release (Optimized) build.
1003 <br><br>
1004
1005 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1006 <dd>
1007 Perform a Release (Optimized) build without assertions enabled.
1008 <br><br>
1009
1010 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1011 <dd>
1012 Perform a Profiling build.
1013 <br><br>
1014
1015 <dt><tt>gmake VERBOSE=1</tt>
1016 <dd>
1017 Print what <tt>gmake</tt> is doing on standard output.
1018 <br><br>
1019
1020 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1021 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1022 the standard output. This also implies <tt>VERBOSE=1</tt>.
1023 <br><br></dd>
1024</dl>
1025
1026<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1027it and any subdirectories that it contains. Entering any directory inside the
1028LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1029that directory that is out of date.</p>
1030
1031</div>
1032
1033<!-- ======================================================================= -->
1034<div class="doc_subsection">
1035 <a name="cross-compile">Cross-Compiling LLVM</a>
1036</div>
1037
1038<div class="doc_text">
1039 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1040 executables and libraries for a platform different than the one one which you
1041 are compiling. To do this, a few additional steps are
1042 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1043 these instructions:</p>
1044 <ol>
1045 <li>Configure and build LLVM as a native compiler. You will need
1046 just <tt>TableGen</tt> from that build.
1047 <ul>
1048 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1049 <tt>make -C utils/TableGen</tt> after configuring.</li>
1050 <li>Otherwise you will need to monitor building process and terminate
1051 it just after <tt>TableGen</tt> was built.</li>
1052 </ul>
1053 </li>
1054 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1055 </li>
1056 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1057 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1058 are different. The values of these options must be legal target triples
1059 that your GCC compiler supports.</li>
1060 <li>Put the saved <tt>TableGen</tt> executable into the
1061 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1062 <tt>.../Release/bin</tt> for a Release build).</li>
1063 <li>Build LLVM as usual.</li>
1064 </ol>
1065 <p>The result of such a build will produce executables that are not executable
1066 on your build host (--build option) but can be executed on your compile host
1067 (--host option).</p>
1068 <p><b>Notes:</b></p>
1069 <div class="doc_notes">
1070 <ol>
1071 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1072 build platform and Windows as host using mingw32 cross-compiler. Other
1073 combinations have not been tested.</li>
1074 </ol>
1075 </div>
1076</div>
1077
1078<!-- ======================================================================= -->
1079<div class="doc_subsection">
1080 <a name="objfiles">The Location of LLVM Object Files</a>
1081</div>
1082
1083<div class="doc_text">
1084
1085<p>The LLVM build system is capable of sharing a single LLVM source tree among
1086several LLVM builds. Hence, it is possible to build LLVM for several different
1087platforms or configurations using the same source tree.</p>
1088
1089<p>This is accomplished in the typical autoconf manner:</p>
1090
1091<ul>
1092 <li><p>Change directory to where the LLVM object files should live:</p>
1093
1094 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1095
1096 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1097 directory:</p>
1098
1099 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1100</ul>
1101
1102<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1103named after the build type:</p>
1104
1105<dl>
1106 <dt>Debug Builds
1107 <dd>
1108 <dl>
1109 <dt>Tools
1110 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1111 <dt>Libraries
1112 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1113 </dl>
1114 <br><br>
1115
1116 <dt>Release Builds
1117 <dd>
1118 <dl>
1119 <dt>Tools
1120 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1121 <dt>Libraries
1122 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1123 </dl>
1124 <br><br>
1125
1126 <dt>Profile Builds
1127 <dd>
1128 <dl>
1129 <dt>Tools
1130 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1131 <dt>Libraries
1132 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1133 </dl>
1134</dl>
1135
1136</div>
1137
1138<!-- ======================================================================= -->
1139<div class="doc_subsection">
1140 <a name="optionalconfig">Optional Configuration Items</a>
1141</div>
1142
1143<div class="doc_text">
1144
1145<p>
1146If you're running on a Linux system that supports the "<a
1147href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1148module, and you have root access on the system, you can set your system up to
1149execute LLVM bitcode files directly. To do this, use commands like this (the
1150first command may not be required if you are already using the module):</p>
1151
1152<div class="doc_code">
1153<pre>
1154$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1155$ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1156$ chmod u+x hello.bc (if needed)
1157$ ./hello.bc
1158</pre>
1159</div>
1160
1161<p>
1162This allows you to execute LLVM bitcode files directly. Thanks to Jack
1163Cummings for pointing this out!
1164</p>
1165
1166</div>
1167
1168
1169<!-- *********************************************************************** -->
1170<div class="doc_section">
1171 <a name="layout"><b>Program Layout</b></a>
1172</div>
1173<!-- *********************************************************************** -->
1174
1175<div class="doc_text">
1176
1177<p>One useful source of information about the LLVM source base is the LLVM <a
1178href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1179href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1180The following is a brief introduction to code layout:</p>
1181
1182</div>
1183
1184<!-- ======================================================================= -->
1185<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1186<div class="doc_text">
1187 <p>This directory contains some simple examples of how to use the LLVM IR and
1188 JIT.</p>
1189</div>
1190
1191<!-- ======================================================================= -->
1192<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1193<div class="doc_text">
1194
1195<p>This directory contains public header files exported from the LLVM
1196library. The three main subdirectories of this directory are:</p>
1197
1198<dl>
1199 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1200 <dd>This directory contains all of the LLVM specific header files. This
1201 directory also has subdirectories for different portions of LLVM:
1202 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1203 etc...</dd>
1204
1205 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1206 <dd>This directory contains generic support libraries that are provided with
1207 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1208 and a Command Line option processing library store their header files here.
1209 </dd>
1210
1211 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1212 <dd>This directory contains header files configured by the <tt>configure</tt>
1213 script. They wrap "standard" UNIX and C header files. Source code can
1214 include these header files which automatically take care of the conditional
1215 #includes that the <tt>configure</tt> script generates.</dd>
1216</dl>
1217</div>
1218
1219<!-- ======================================================================= -->
1220<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1221<div class="doc_text">
1222
1223<p>This directory contains most of the source files of the LLVM system. In LLVM,
1224almost all code exists in libraries, making it very easy to share code among the
1225different <a href="#tools">tools</a>.</p>
1226
1227<dl>
1228 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1229 <dd> This directory holds the core LLVM source files that implement core
1230 classes like Instruction and BasicBlock.</dd>
1231
1232 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1233 <dd>This directory holds the source code for the LLVM assembly language parser
1234 library.</dd>
1235
1236 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1237 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1238
1239 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1240 different program analyses, such as Dominator Information, Call Graphs,
1241 Induction Variables, Interval Identification, Natural Loop Identification,
1242 etc.</dd>
1243
1244 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1245 <dd> This directory contains the source code for the LLVM to LLVM program
1246 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1247 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1248 Elimination, and many others.</dd>
1249
1250 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1251 <dd> This directory contains files that describe various target architectures
1252 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1253 directory holds the X86 machine description while
1254 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1255
1256 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1257 <dd> This directory contains the major parts of the code generator: Instruction
1258 Selector, Instruction Scheduling, and Register Allocation.</dd>
1259
1260 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1261 <dd> This directory contains the source level debugger library that makes
1262 it possible to instrument LLVM programs so that a debugger could identify
1263 source code locations at which the program is executing.</dd>
1264
1265 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1266 <dd> This directory contains libraries for executing LLVM bitcode directly
1267 at runtime in both interpreted and JIT compiled fashions.</dd>
1268
1269 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1270 <dd> This directory contains the source code that corresponds to the header
1271 files located in <tt>llvm/include/Support/</tt>.</dd>
1272
1273 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1274 <dd>This directory contains the operating system abstraction layer that
1275 shields LLVM from platform-specific coding.</dd>
1276</dl>
1277
1278</div>
1279
1280<!-- ======================================================================= -->
1281<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1282<div class="doc_text">
1283 <p>This directory contains projects that are not strictly part of LLVM but are
1284 shipped with LLVM. This is also the directory where you should create your own
1285 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1286 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1287 functional example of a compiler front end.</p>
1288</div>
1289
1290<!-- ======================================================================= -->
1291<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1292<div class="doc_text">
1293
1294<p>This directory contains libraries which are compiled into LLVM bitcode and
1295used when linking programs with the GCC front end. Most of these libraries are
1296skeleton versions of real libraries; for example, libc is a stripped down
1297version of glibc.</p>
1298
1299<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1300end to compile.</p>
1301
1302</div>
1303
1304<!-- ======================================================================= -->
1305<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1306<div class="doc_text">
1307 <p>This directory contains feature and regression tests and other basic sanity
1308 checks on the LLVM infrastructure. These are intended to run quickly and cover
1309 a lot of territory without being exhaustive.</p>
1310</div>
1311
1312<!-- ======================================================================= -->
1313<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1314<div class="doc_text">
1315 <p>This is not a directory in the normal llvm module; it is a separate
1316 Subversion
1317 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1318 This
1319 module contains a comprehensive correctness, performance, and benchmarking
1320 test
1321 suite for LLVM. It is a separate Subversion module because not every LLVM
1322 user is
1323 interested in downloading or building such a comprehensive test suite. For
1324 further details on this test suite, please see the
1325 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1326</div>
1327
1328<!-- ======================================================================= -->
1329<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1330<div class="doc_text">
1331
1332<p>The <b>tools</b> directory contains the executables built out of the
1333libraries above, which form the main part of the user interface. You can
1334always get help for a tool by typing <tt>tool_name --help</tt>. The
1335following is a brief introduction to the most important tools. More detailed
1336information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1337
1338<dl>
1339
1340 <dt><tt><b>bugpoint</b></tt></dt>
1341 <dd><tt>bugpoint</tt> is used to debug
1342 optimization passes or code generation backends by narrowing down the
1343 given test case to the minimum number of passes and/or instructions that
1344 still cause a problem, whether it is a crash or miscompilation. See <a
1345 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1346 on using <tt>bugpoint</tt>.</dd>
1347
1348 <dt><tt><b>llvmc</b></tt></dt>
1349 <dd>The LLVM Compiler Driver. This program can
1350 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1351 pre-processing, translation, optimization, assembly, and linking of programs
1352 all from one command line. <tt>llvmc</tt> also takes care of processing the
1353 dependent libraries found in bitcode. This reduces the need to get the
1354 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1355 note that this tool, while functional, is still experimental and not feature
1356 complete.</dd>
1357
1358 <dt><tt><b>llvm-ar</b></tt></dt>
1359 <dd>The archiver produces an archive containing
1360 the given LLVM bitcode files, optionally with an index for faster
1361 lookup.</dd>
1362
1363 <dt><tt><b>llvm-as</b></tt></dt>
1364 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1365 bitcode.</dd>
1366
1367 <dt><tt><b>llvm-dis</b></tt></dt>
1368 <dd>The disassembler transforms the LLVM bitcode to human readable
1369 LLVM assembly.</dd>
1370
1371 <dt><tt><b>llvm-ld</b></tt></dt>
1372 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1373 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1374 optimizations and allows optimization modules to be loaded and run so that
1375 language specific optimizations can be applied at link time.</dd>
1376
1377 <dt><tt><b>llvm-link</b></tt></dt>
1378 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1379 a single program.</dd>
1380
1381 <dt><tt><b>lli</b></tt></dt>
1382 <dd><tt>lli</tt> is the LLVM interpreter, which
Nick Lewycky32dc2a12007-12-03 01:58:01 +0000[diff] [blame]1383 can directly execute LLVM bitcode (although very slowly...). For architectures
1384 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1385 will function as a Just-In-Time compiler (if the functionality was compiled
1386 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1387
1388 <dt><tt><b>llc</b></tt></dt>
1389 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1390 translates LLVM bitcode to a native code assembly file or to C code (with
1391 the -march=c option).</dd>
1392
1393 <dt><tt><b>llvm-gcc</b></tt></dt>
1394 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1395 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1396 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1397 usual machine code output. It works just like any other GCC compiler,
1398 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1399 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1400 separate Subversion module.</dd>
1401
1402 <dt><tt><b>opt</b></tt></dt>
1403 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1404 transformations (which are specified on the command line), and then outputs
1405 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1406 get a list of the program transformations available in LLVM.<br/>
1407 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1408 LLVM bitcode file and print out the results. It is primarily useful for
1409 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1410</dl>
1411</div>
1412
1413<!-- ======================================================================= -->
1414<div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1415<div class="doc_text">
1416
1417<p>This directory contains utilities for working with LLVM source code, and some
1418of the utilities are actually required as part of the build process because they
1419are code generators for parts of LLVM infrastructure.</p>
1420
1421<dl>
1422 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1423 that finds differences between code that LLC generates and code that LLI
1424 generates. This is a useful tool if you are debugging one of them,
1425 assuming that the other generates correct output. For the full user
1426 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1427
1428 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1429 syntax-highlighting files which will work with Emacs and XEmacs editors,
1430 providing syntax highlighting support for LLVM assembly files and TableGen
1431 description files. For information on how to use the syntax files, consult
1432 the <tt>README</tt> file in that directory.<br><br>
1433
1434 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1435 and outputs all non-generated source files, which is useful if one wishes
1436 to do a lot of development across directories and does not want to
1437 individually find each file. One way to use it is to run, for example:
1438 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1439 tree.<br><br>
1440
1441 <dt><tt><b>llvmgrep</b></tt></dt>
1442 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1443 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1444 line. This is a very efficient way of searching the source base for a
1445 particular regular expression.</dd>
1446
1447 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1448 files in the current directory and then compiles and links the tool that
1449 is the first argument. For example, assuming you are in the directory
1450 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1451 simply running <tt>makellvm llc</tt> will make a build of the current
1452 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1453 causing a re-linking of LLC.<br><br>
1454
1455 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1456 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1457 cron script to generate nightly status reports of the functionality of
1458 tools, and the results can be seen by following the appropriate link on
1459 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1460
1461 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1462 the tool used to generate register descriptions, instruction set
1463 descriptions, and even assemblers from common TableGen description
1464 files.<br><br>
1465
1466 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1467 syntax-highlighting files which will work with the VIM editor, providing
1468 syntax highlighting support for LLVM assembly files and TableGen
1469 description files. For information on how to use the syntax files, consult
1470 the <tt>README</tt> file in that directory.<br><br>
1471
1472</dl>
1473
1474</div>
1475
1476<!-- ======================================================================= -->
1477<div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1478<div class="doc_text">
1479 <p>This directory contains build scripts and project files for use with
1480 Visual C++. This allows developers on Windows to build LLVM without the need
1481 for Cygwin. The contents of this directory should be considered experimental
1482 at this time.
1483 </p>
1484</div>
1485<!-- *********************************************************************** -->
1486<div class="doc_section">
1487 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1488</div>
1489<!-- *********************************************************************** -->
1490
1491<div class="doc_text">
1492<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1493so we only include instructiosn for llvm-gcc4.
1494</p>
1495
1496<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1497from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1498create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1499the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1500<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1501output.</p>
1502</div>
1503
1504<!-- ======================================================================= -->
1505<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1506
1507<div class="doc_text">
1508
1509<ol>
1510 <li><p>First, create a simple C file, name it 'hello.c':</p>
1511
1512<div class="doc_code">
1513<pre>
1514#include &lt;stdio.h&gt;
1515
1516int main() {
1517 printf("hello world\n");
1518 return 0;
1519}
1520</pre></div></li>
1521
1522 <li><p>Next, compile the C file into a native executable:</p>
1523
1524 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1525
1526 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1527 -c arguments work as usual (producing a native .s or .o file,
1528 respectively).</p></li>
1529
1530 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1531
1532 <div class="doc_code">
1533 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1534
1535 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1536 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1537 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1538 the bitcode file.</p>
1539
1540 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1541 </p></li>
1542
1543 <li><p>Run the program in both forms. To run the program, use:</p>
1544
1545 <div class="doc_code"><pre>% ./hello</pre></div>
1546
1547 <p>and</p>
1548
1549 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1550
1551 <p>The second examples shows how to invoke the LLVM JIT, <a
1552 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1553
1554 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1555 code:</p>
1556
1557<div class="doc_code">
1558<pre>llvm-dis &lt; hello.bc | less</pre>
1559</div></li>
1560
1561 <li><p>Compile the program to native assembly using the LLC code
1562 generator:</p>
1563
1564 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1565
1566 <li><p>Assemble the native assembly language file into a program:</p>
1567
1568<div class="doc_code">
1569<pre>
1570<b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1571
1572<b>Others:</b> % gcc hello.s -o hello.native
1573</pre>
1574</div></li>
1575
1576 <li><p>Execute the native code program:</p>
1577
1578 <div class="doc_code"><pre>% ./hello.native</pre></div>
1579
1580 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1581 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1582 </li>
1583
1584</ol>
1585
1586</div>
1587
1588
1589<!-- *********************************************************************** -->
1590<div class="doc_section">
1591 <a name="problems">Common Problems</a>
1592</div>
1593<!-- *********************************************************************** -->
1594
1595<div class="doc_text">
1596
1597<p>If you are having problems building or using LLVM, or if you have any other
1598general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1599Asked Questions</a> page.</p>
1600
1601</div>
1602
1603<!-- *********************************************************************** -->
1604<div class="doc_section">
1605 <a name="links">Links</a>
1606</div>
1607<!-- *********************************************************************** -->
1608
1609<div class="doc_text">
1610
1611<p>This document is just an <b>introduction</b> to how to use LLVM to do
1612some simple things... there are many more interesting and complicated things
1613that you can do that aren't documented here (but we'll gladly accept a patch
1614if you want to write something up!). For more information about LLVM, check
1615out:</p>
1616
1617<ul>
1618 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1619 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1620 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1621 that Uses LLVM</a></li>
1622</ul>
1623
1624</div>
1625
1626<!-- *********************************************************************** -->
1627
1628<hr>
1629<address>
1630 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1631 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
1632 <a href="http://validator.w3.org/check/referer"><img
1633 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
1634
1635 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1636 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1637 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1638 Last modified: $Date$
1639</address>
1640</body>
1641</html>