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6 <title>Getting Started with LLVM System</title>
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8</head>
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>
20 <li><a href="#hardware">Hardware</a>
21 <li><a href="#software">Software</a>
22 <li><a href="#brokengcc">Broken versions of GCC and other tools</a>
23 </ol></li>
24
25 <li><a href="#starting">Getting Started with LLVM</a>
26 <ol>
27 <li><a href="#terminology">Terminology and Notation</a>
28 <li><a href="#environment">Setting Up Your Environment</a>
29 <li><a href="#unpack">Unpacking the LLVM Archives</a>
30 <li><a href="#checkout">Checkout LLVM from Subversion</a>
31 <li><a href="#installcf">Install the GCC Front End</a>
32 <li><a href="#config">Local LLVM Configuration</a>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
34 <li><a href="#cross-compile">Cross-Compiling LLVM</a>
35 <li><a href="#objfiles">The Location of LLVM Object Files</a>
36 <li><a href="#optionalconfig">Optional Configuration Items</a>
37 </ol></li>
38
39 <li><a href="#layout">Program layout</a>
40 <ol>
41 <li><a href="#examples"><tt>llvm/examples</tt></a>
42 <li><a href="#include"><tt>llvm/include</tt></a>
43 <li><a href="#lib"><tt>llvm/lib</tt></a>
44 <li><a href="#projects"><tt>llvm/projects</tt></a>
45 <li><a href="#runtime"><tt>llvm/runtime</tt></a>
46 <li><a href="#test"><tt>llvm/test</tt></a>
47 <li><a href="#llvmtest"><tt>llvm-test</tt></a>
48 <li><a href="#tools"><tt>llvm/tools</tt></a>
49 <li><a href="#utils"><tt>llvm/utils</tt></a>
50 <li><a href="#win32"><tt>llvm/win32</tt></a>
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>
472 <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
473 <li><b>find</b> - find files/dirs in a file system</li>
474 <li><b>grep</b> - regular expression search utility</li>
475 <li><b>gzip*</b> - gzip command for distribution generation</li>
476 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
477 <li><b>install</b> - install directories/files </li>
478 <li><b>mkdir</b> - create a directory</li>
479 <li><b>mv</b> - move (rename) files</li>
480 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
481 <li><b>rm</b> - remove (delete) files and directories</li>
482 <li><b>sed</b> - stream editor for transforming output</li>
483 <li><b>sh</b> - Bourne shell for make build scripts</li>
484 <li><b>tar</b> - tape archive for distribution generation</li>
485 <li><b>test</b> - test things in file system</li>
486 <li><b>unzip*</b> - unzip command for distribution checking</li>
487 <li><b>zip*</b> - zip command for distribution generation</li>
488 </ul>
489</div>
490
491<!-- ======================================================================= -->
492<div class="doc_subsection">
493 <a name="brokengcc">Broken versions of GCC and other tools</a>
494</div>
495
496<div class="doc_text">
497
498<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
499bugs in the compiler. In particular, several versions of GCC crash when trying
500to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
501successfully with them (however, see important notes below). Other versions
502of GCC will probably work as well. GCC versions listed
503here are known to not work. If you are using one of these versions, please try
504to upgrade your GCC to something more recent. If you run into a problem with a
505version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
506us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
507of GCC you are using.
508</p>
509
510<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
511problems in the STL that effectively prevent it from compiling LLVM.
512</p>
513
514<p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
515
516<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
517href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
518the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
519
520<p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
521 Cygwin does not work. Please <a href="CFEBuildInstrs.html#cygwin">upgrade
522 to a newer version</a> if possible.</p>
523<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
524 possibly others) does not compile LLVM correctly (it appears that exception
525 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
526 to a newer version of GCC.</p>
527<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
528 code generator, causing an infinite loop in the llvm-gcc build when built
529 with optimizations enabled (i.e. a release build).</p>
530<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
531 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
532 correctly compiles LLVM at -O2. A work around is to build release LLVM
533 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
534<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
535 miscompiles portions of LLVM</a>.</p>
536<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
537 miscompile LLVM.</p>
538<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
539 default with ENABLE_OPTIMIZED=1. To work around this, build with
540 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
541<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
542 compiling some files. At the time of this writing, GCC mainline (4.2)
543 did not share the problem.</p>
544<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
545 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
546 code. LLVM will appear to mostly work but will be buggy, e.g. failing
547 portions of its testsuite.</p>
548<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
549platforms compiling md5.c gets a mangled constant.</p>
550<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
551long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
552defined in a discarded section. You can safely ignore these messages as they are
553erroneous and the linkage is correct. These messages disappear using ld
5542.17.</p>
555
556<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
557href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
558causes huge link times (minutes instead of seconds) when building LLVM. We
559recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
560
561</div>
562
563
564
565<!-- *********************************************************************** -->
566<div class="doc_section">
567 <a name="starting"><b>Getting Started with LLVM</b></a>
568</div>
569<!-- *********************************************************************** -->
570
571<div class="doc_text">
572
573<p>The remainder of this guide is meant to get you up and running with
574LLVM and to give you some basic information about the LLVM environment.</p>
575
576<p>The later sections of this guide describe the <a
577href="#layout">general layout</a> of the the LLVM source tree, a <a
578href="#tutorial">simple example</a> using the LLVM tool chain, and <a
579href="#links">links</a> to find more information about LLVM or to get
580help via e-mail.</p>
581</div>
582
583<!-- ======================================================================= -->
584<div class="doc_subsection">
585 <a name="terminology">Terminology and Notation</a>
586</div>
587
588<div class="doc_text">
589
590<p>Throughout this manual, the following names are used to denote paths
591specific to the local system and working environment. <i>These are not
592environment variables you need to set but just strings used in the rest
593of this document below</i>. In any of the examples below, simply replace
594each of these names with the appropriate pathname on your local system.
595All these paths are absolute:</p>
596
597<dl>
598 <dt>SRC_ROOT
599 <dd>
600 This is the top level directory of the LLVM source tree.
601 <br><br>
602
603 <dt>OBJ_ROOT
604 <dd>
605 This is the top level directory of the LLVM object tree (i.e. the
606 tree where object files and compiled programs will be placed. It
607 can be the same as SRC_ROOT).
608 <br><br>
609
610 <dt>LLVMGCCDIR
611 <dd>
612 This is where the LLVM GCC Front End is installed.
613 <p>
614 For the pre-built GCC front end binaries, the LLVMGCCDIR is
615 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
616</dl>
617
618</div>
619
620<!-- ======================================================================= -->
621<div class="doc_subsection">
622 <a name="environment">Setting Up Your Environment</a>
623</div>
624
625<div class="doc_text">
626
627<p>
628In order to compile and use LLVM, you may need to set some environment
629variables.
630
631<dl>
632 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
633 <dd>[Optional] This environment variable helps LLVM linking tools find the
634 locations of your bitcode libraries. It is provided only as a
635 convenience since you can specify the paths using the -L options of the
636 tools and the C/C++ front-end will automatically use the bitcode files
637 installed in its
638 <tt>lib</tt> directory.</dd>
639</dl>
640
641</div>
642
643<!-- ======================================================================= -->
644<div class="doc_subsection">
645 <a name="unpack">Unpacking the LLVM Archives</a>
646</div>
647
648<div class="doc_text">
649
650<p>
651If you have the LLVM distribution, you will need to unpack it before you
652can begin to compile it. LLVM is distributed as a set of two files: the LLVM
653suite and the LLVM GCC front end compiled for your platform. There is an
654additional test suite that is optional. Each file is a TAR archive that is
655compressed with the gzip program.
656</p>
657
658<p>The files are as follows, with <em>x.y</em> marking the version number:
659<dl>
660 <dt><tt>llvm-x.y.tar.gz</tt></dt>
661 <dd>Source release for the LLVM libraries and tools.<br/></dd>
662
663 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
664 <dd>Source release for the LLVM test suite.</dd>
665
666 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
667 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
668 directory for build instructions.<br/></dd>
669
670 <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
671 <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
672
673</dl>
674
675<p>It is also possible to download the sources of the llvm-gcc4 front end from a
676read-only subversion mirror at
677svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
678
679</div>
680
681<!-- ======================================================================= -->
682<div class="doc_subsection">
683 <a name="checkout">Checkout LLVM from Subversion</a>
684</div>
685
686<div class="doc_text">
687
688<p>If you have access to our Subversion repository, you can get a fresh copy of
689the entire source code. All you need to do is check it out from Subvresion as
690follows:</p>
691
692<ul>
693 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
694 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
695 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
696 llvm</tt></li>
697</ul>
698
699
700<p>This will create an '<tt>llvm</tt>' directory in the current
701directory and fully populate it with the LLVM source code, Makefiles,
702test directories, and local copies of documentation files.</p>
703
704<p>If you want to get a specific release (as opposed to the most recent
705revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
706'<tt>trunk</tt>'). The following releases are located in the following
707 subdirectories of the '<tt>tags</tt>' directory:</p>
708
709<ul>
Tanya Lattner2fad5b02007-09-28 22:50:54 +0000[diff] [blame^]710<li>Release 2.1: <b>RELEASE_21</b></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]711<li>Release 2.0: <b>RELEASE_20</b></li>
712<li>Release 1.9: <b>RELEASE_19</b></li>
713<li>Release 1.8: <b>RELEASE_18</b></li>
714<li>Release 1.7: <b>RELEASE_17</b></li>
715<li>Release 1.6: <b>RELEASE_16</b></li>
716<li>Release 1.5: <b>RELEASE_15</b></li>
717<li>Release 1.4: <b>RELEASE_14</b></li>
718<li>Release 1.3: <b>RELEASE_13</b></li>
719<li>Release 1.2: <b>RELEASE_12</b></li>
720<li>Release 1.1: <b>RELEASE_11</b></li>
721<li>Release 1.0: <b>RELEASE_1</b></li>
722</ul>
723
724<p>If you would like to get the LLVM test suite (a separate package as of 1.4),
725you get it from the Subversion repository:</p>
726
727<div class="doc_code">
728<pre>
729% cd llvm/projects
730% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
731</pre>
732</div>
733
734<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
735configured by the LLVM configure script as well as automatically updated when
736you run <tt>svn update</tt>.</p>
737
738<p>If you would like to get the GCC front end source code, you can also get it
739and build it yourself. Please follow <a href="CFEBuildInstrs.html">these
740instructions</a> to successfully get and build the LLVM GCC front-end.</p>
741
742</div>
743
744<!-- ======================================================================= -->
745<div class="doc_subsection">
746 <a name="installcf">Install the GCC Front End</a>
747</div>
748
749<div class="doc_text">
750
751<p>Before configuring and compiling the LLVM suite, you can optionally extract the
752LLVM GCC front end from the binary distribution. It is used for running the
753llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
754<a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
755main LLVM repository.</p>
756
757<p>To install the GCC front end, do the following:</p>
758
759<ol>
760 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
761 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
762 -</tt></li>
763</ol>
764
765<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
766llvm-g++ to some directory in your path. When you configure LLVM, it will
767automatically detect llvm-gcc's presence (if it is in your path) enabling its
768use in llvm-test. Note that you can always build or install llvm-gcc at any
769pointer after building the main LLVM repository: just reconfigure llvm and
770llvm-test will pick it up.
771</p>
772
773<p>The binary versions of the GCC front end may not suit all of your needs. For
774example, the binary distribution may include an old version of a system header
775file, not "fix" a header file that needs to be fixed for GCC, or it may be
776linked with libraries not available on your system.</p>
777
778<p>In cases like these, you may want to try <a
779href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
780much easier now than it was in the past.</p>
781
782</div>
783
784<!-- ======================================================================= -->
785<div class="doc_subsection">
786 <a name="config">Local LLVM Configuration</a>
787</div>
788
789<div class="doc_text">
790
791 <p>Once checked out from the Subversion repository, the LLVM suite source
792 code must be
793configured via the <tt>configure</tt> script. This script sets variables in the
794various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
795<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
796the Makefiles needed to begin building LLVM.</p>
797
798<p>The following environment variables are used by the <tt>configure</tt>
799script to configure the build system:</p>
800
801<table summary="LLVM configure script environment variables">
802 <tr><th>Variable</th><th>Purpose</th></tr>
803 <tr>
804 <td>CC</td>
805 <td>Tells <tt>configure</tt> which C compiler to use. By default,
806 <tt>configure</tt> will look for the first GCC C compiler in
807 <tt>PATH</tt>. Use this variable to override
808 <tt>configure</tt>'s default behavior.</td>
809 </tr>
810 <tr>
811 <td>CXX</td>
812 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
813 <tt>configure</tt> will look for the first GCC C++ compiler in
814 <tt>PATH</tt>. Use this variable to override
815 <tt>configure</tt>'s default behavior.</td>
816 </tr>
817</table>
818
819<p>The following options can be used to set or enable LLVM specific options:</p>
820
821<dl>
822 <dt><i>--with-llvmgccdir</i></dt>
823 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
824 The value of this option should specify the full pathname of the C/C++ Front
825 End to be used. If this option is not provided, the PATH will be searched for
826 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
827 be inferred from the path found. If the option is not given, and no llvm-gcc
828 can be found in the path then a warning will be produced by
829 <tt>configure</tt> indicating this situation. LLVM may still be built with
830 the <tt>tools-only</tt> target but attempting to build the runtime libraries
831 will fail as these libraries require llvm-gcc and llvm-g++. See
832 <a href="#installcf">Install the GCC Front End</a> for details on installing
833 the C/C++ Front End. See
834 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
835 for details on building the C/C++ Front End.</dd>
836 <dt><i>--with-tclinclude</i></dt>
837 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
838 found. Use this if you have multiple tcl installations on your machine and you
839 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
840 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
841 option, the LLVM configure script will search for the tcl 8.4 and 8.3
842 releases.
843 <br><br>
844 </dd>
845 <dt><i>--enable-optimized</i></dt>
846 <dd>
847 Enables optimized compilation by default (debugging symbols are removed
848 and GCC optimization flags are enabled). The default is to use an
849 unoptimized build (also known as a debug build).
850 <br><br>
851 </dd>
852 <dt><i>--enable-debug-runtime</i></dt>
853 <dd>
854 Enables debug symbols in the runtime libraries. The default is to strip
855 debug symbols from the runtime libraries.
856 </dd>
857 <dt><i>--enable-jit</i></dt>
858 <dd>
859 Compile the Just In Time (JIT) compiler functionality. This is not
860 available
861 on all platforms. The default is dependent on platform, so it is best
862 to explicitly enable it if you want it.
863 <br><br>
864 </dd>
865 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
866 <dd>Controls which targets will be built and linked into llc. The default
867 value for <tt>target_options</tt> is "all" which builds and links all
868 available targets. The value "host-only" can be specified to build only a
869 native compiler (no cross-compiler targets available). The "native" target is
870 selected as the target of the build host. You can also specify a comma
871 separated list of target names that you want available in llc. The target
872 names use all lower case. The current set of targets is: <br/>
873 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
874 <br><br></dd>
875 <dt><i>--enable-doxygen</i></dt>
876 <dd>Look for the doxygen program and enable construction of doxygen based
877 documentation from the source code. This is disabled by default because
878 generating the documentation can take a long time and producess 100s of
879 megabytes of output.</dd>
880 <dt><i>--with-udis86</i></dt>
881 <dd>LLVM can use external disassembler library for various purposes (now it's
882 used only for examining code produced by JIT). This option will enable usage
883 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
884 bits) disassembler library.</dd>
885</dl>
886
887<p>To configure LLVM, follow these steps:</p>
888
889<ol>
890 <li><p>Change directory into the object root directory:</p>
891
892 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
893
894 <li><p>Run the <tt>configure</tt> script located in the LLVM source
895 tree:</p>
896
897 <div class="doc_code">
898 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
899 </div></li>
900</ol>
901
902</div>
903
904<!-- ======================================================================= -->
905<div class="doc_subsection">
906 <a name="compile">Compiling the LLVM Suite Source Code</a>
907</div>
908
909<div class="doc_text">
910
911<p>Once you have configured LLVM, you can build it. There are three types of
912builds:</p>
913
914<dl>
915 <dt>Debug Builds
916 <dd>
917 These builds are the default when one types <tt>gmake</tt> (unless the
918 <tt>--enable-optimized</tt> option was used during configuration). The
919 build system will compile the tools and libraries with debugging
920 information.
921 <br><br>
922
923 <dt>Release (Optimized) Builds
924 <dd>
925 These builds are enabled with the <tt>--enable-optimized</tt> option to
926 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
927 <tt>gmake</tt> command line. For these builds, the build system will
928 compile the tools and libraries with GCC optimizations enabled and strip
929 debugging information from the libraries and executables it generates.
930 <br><br>
931
932 <dt>Profile Builds
933 <dd>
934 These builds are for use with profiling. They compile profiling
935 information into the code for use with programs like <tt>gprof</tt>.
936 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
937 on the <tt>gmake</tt> command line.
938</dl>
939
940<p>Once you have LLVM configured, you can build it by entering the
941<i>OBJ_ROOT</i> directory and issuing the following command:</p>
942
943<div class="doc_code"><pre>% gmake</pre></div>
944
945<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
946are using a version of GCC that is known not to compile LLVM.</p>
947
948<p>
949If you have multiple processors in your machine, you may wish to use some of
950the parallel build options provided by GNU Make. For example, you could use the
951command:</p>
952
953<div class="doc_code"><pre>% gmake -j2</pre></div>
954
955<p>There are several special targets which are useful when working with the LLVM
956source code:</p>
957
958<dl>
959 <dt><tt>gmake clean</tt>
960 <dd>
961 Removes all files generated by the build. This includes object files,
962 generated C/C++ files, libraries, and executables.
963 <br><br>
964
965 <dt><tt>gmake dist-clean</tt>
966 <dd>
967 Removes everything that <tt>gmake clean</tt> does, but also removes files
968 generated by <tt>configure</tt>. It attempts to return the source tree to the
969 original state in which it was shipped.
970 <br><br>
971
972 <dt><tt>gmake install</tt>
973 <dd>
974 Installs LLVM header files, libraries, tools, and documentation in a
975 hierarchy
976 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
977 defaults to <tt>/usr/local</tt>.
978 <br><br>
979
980 <dt><tt>gmake -C runtime install-bytecode</tt>
981 <dd>
982 Assuming you built LLVM into $OBJDIR, when this command is run, it will
983 install bitcode libraries into the GCC front end's bitcode library
984 directory. If you need to update your bitcode libraries,
985 this is the target to use once you've built them.
986 <br><br>
987</dl>
988
989<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
990details on these <tt>make</tt> targets and descriptions of other targets
991available.</p>
992
993<p>It is also possible to override default values from <tt>configure</tt> by
994declaring variables on the command line. The following are some examples:</p>
995
996<dl>
997 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
998 <dd>
999 Perform a Release (Optimized) build.
1000 <br><br>
1001
1002 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1003 <dd>
1004 Perform a Release (Optimized) build without assertions enabled.
1005 <br><br>
1006
1007 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1008 <dd>
1009 Perform a Profiling build.
1010 <br><br>
1011
1012 <dt><tt>gmake VERBOSE=1</tt>
1013 <dd>
1014 Print what <tt>gmake</tt> is doing on standard output.
1015 <br><br>
1016
1017 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1018 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1019 the standard output. This also implies <tt>VERBOSE=1</tt>.
1020 <br><br></dd>
1021</dl>
1022
1023<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1024it and any subdirectories that it contains. Entering any directory inside the
1025LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1026that directory that is out of date.</p>
1027
1028</div>
1029
1030<!-- ======================================================================= -->
1031<div class="doc_subsection">
1032 <a name="cross-compile">Cross-Compiling LLVM</a>
1033</div>
1034
1035<div class="doc_text">
1036 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1037 executables and libraries for a platform different than the one one which you
1038 are compiling. To do this, a few additional steps are
1039 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1040 these instructions:</p>
1041 <ol>
1042 <li>Configure and build LLVM as a native compiler. You will need
1043 just <tt>TableGen</tt> from that build.
1044 <ul>
1045 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1046 <tt>make -C utils/TableGen</tt> after configuring.</li>
1047 <li>Otherwise you will need to monitor building process and terminate
1048 it just after <tt>TableGen</tt> was built.</li>
1049 </ul>
1050 </li>
1051 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1052 </li>
1053 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1054 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1055 are different. The values of these options must be legal target triples
1056 that your GCC compiler supports.</li>
1057 <li>Put the saved <tt>TableGen</tt> executable into the
1058 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1059 <tt>.../Release/bin</tt> for a Release build).</li>
1060 <li>Build LLVM as usual.</li>
1061 </ol>
1062 <p>The result of such a build will produce executables that are not executable
1063 on your build host (--build option) but can be executed on your compile host
1064 (--host option).</p>
1065 <p><b>Notes:</b></p>
1066 <div class="doc_notes">
1067 <ol>
1068 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1069 build platform and Windows as host using mingw32 cross-compiler. Other
1070 combinations have not been tested.</li>
1071 </ol>
1072 </div>
1073</div>
1074
1075<!-- ======================================================================= -->
1076<div class="doc_subsection">
1077 <a name="objfiles">The Location of LLVM Object Files</a>
1078</div>
1079
1080<div class="doc_text">
1081
1082<p>The LLVM build system is capable of sharing a single LLVM source tree among
1083several LLVM builds. Hence, it is possible to build LLVM for several different
1084platforms or configurations using the same source tree.</p>
1085
1086<p>This is accomplished in the typical autoconf manner:</p>
1087
1088<ul>
1089 <li><p>Change directory to where the LLVM object files should live:</p>
1090
1091 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1092
1093 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1094 directory:</p>
1095
1096 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1097</ul>
1098
1099<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1100named after the build type:</p>
1101
1102<dl>
1103 <dt>Debug Builds
1104 <dd>
1105 <dl>
1106 <dt>Tools
1107 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1108 <dt>Libraries
1109 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1110 </dl>
1111 <br><br>
1112
1113 <dt>Release Builds
1114 <dd>
1115 <dl>
1116 <dt>Tools
1117 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1118 <dt>Libraries
1119 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1120 </dl>
1121 <br><br>
1122
1123 <dt>Profile Builds
1124 <dd>
1125 <dl>
1126 <dt>Tools
1127 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1128 <dt>Libraries
1129 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1130 </dl>
1131</dl>
1132
1133</div>
1134
1135<!-- ======================================================================= -->
1136<div class="doc_subsection">
1137 <a name="optionalconfig">Optional Configuration Items</a>
1138</div>
1139
1140<div class="doc_text">
1141
1142<p>
1143If you're running on a Linux system that supports the "<a
1144href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1145module, and you have root access on the system, you can set your system up to
1146execute LLVM bitcode files directly. To do this, use commands like this (the
1147first command may not be required if you are already using the module):</p>
1148
1149<div class="doc_code">
1150<pre>
1151$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1152$ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1153$ chmod u+x hello.bc (if needed)
1154$ ./hello.bc
1155</pre>
1156</div>
1157
1158<p>
1159This allows you to execute LLVM bitcode files directly. Thanks to Jack
1160Cummings for pointing this out!
1161</p>
1162
1163</div>
1164
1165
1166<!-- *********************************************************************** -->
1167<div class="doc_section">
1168 <a name="layout"><b>Program Layout</b></a>
1169</div>
1170<!-- *********************************************************************** -->
1171
1172<div class="doc_text">
1173
1174<p>One useful source of information about the LLVM source base is the LLVM <a
1175href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1176href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1177The following is a brief introduction to code layout:</p>
1178
1179</div>
1180
1181<!-- ======================================================================= -->
1182<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1183<div class="doc_text">
1184 <p>This directory contains some simple examples of how to use the LLVM IR and
1185 JIT.</p>
1186</div>
1187
1188<!-- ======================================================================= -->
1189<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1190<div class="doc_text">
1191
1192<p>This directory contains public header files exported from the LLVM
1193library. The three main subdirectories of this directory are:</p>
1194
1195<dl>
1196 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1197 <dd>This directory contains all of the LLVM specific header files. This
1198 directory also has subdirectories for different portions of LLVM:
1199 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1200 etc...</dd>
1201
1202 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1203 <dd>This directory contains generic support libraries that are provided with
1204 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1205 and a Command Line option processing library store their header files here.
1206 </dd>
1207
1208 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1209 <dd>This directory contains header files configured by the <tt>configure</tt>
1210 script. They wrap "standard" UNIX and C header files. Source code can
1211 include these header files which automatically take care of the conditional
1212 #includes that the <tt>configure</tt> script generates.</dd>
1213</dl>
1214</div>
1215
1216<!-- ======================================================================= -->
1217<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1218<div class="doc_text">
1219
1220<p>This directory contains most of the source files of the LLVM system. In LLVM,
1221almost all code exists in libraries, making it very easy to share code among the
1222different <a href="#tools">tools</a>.</p>
1223
1224<dl>
1225 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1226 <dd> This directory holds the core LLVM source files that implement core
1227 classes like Instruction and BasicBlock.</dd>
1228
1229 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1230 <dd>This directory holds the source code for the LLVM assembly language parser
1231 library.</dd>
1232
1233 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1234 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1235
1236 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1237 different program analyses, such as Dominator Information, Call Graphs,
1238 Induction Variables, Interval Identification, Natural Loop Identification,
1239 etc.</dd>
1240
1241 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1242 <dd> This directory contains the source code for the LLVM to LLVM program
1243 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1244 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1245 Elimination, and many others.</dd>
1246
1247 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1248 <dd> This directory contains files that describe various target architectures
1249 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1250 directory holds the X86 machine description while
1251 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1252
1253 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1254 <dd> This directory contains the major parts of the code generator: Instruction
1255 Selector, Instruction Scheduling, and Register Allocation.</dd>
1256
1257 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1258 <dd> This directory contains the source level debugger library that makes
1259 it possible to instrument LLVM programs so that a debugger could identify
1260 source code locations at which the program is executing.</dd>
1261
1262 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1263 <dd> This directory contains libraries for executing LLVM bitcode directly
1264 at runtime in both interpreted and JIT compiled fashions.</dd>
1265
1266 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1267 <dd> This directory contains the source code that corresponds to the header
1268 files located in <tt>llvm/include/Support/</tt>.</dd>
1269
1270 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1271 <dd>This directory contains the operating system abstraction layer that
1272 shields LLVM from platform-specific coding.</dd>
1273</dl>
1274
1275</div>
1276
1277<!-- ======================================================================= -->
1278<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1279<div class="doc_text">
1280 <p>This directory contains projects that are not strictly part of LLVM but are
1281 shipped with LLVM. This is also the directory where you should create your own
1282 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1283 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1284 functional example of a compiler front end.</p>
1285</div>
1286
1287<!-- ======================================================================= -->
1288<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1289<div class="doc_text">
1290
1291<p>This directory contains libraries which are compiled into LLVM bitcode and
1292used when linking programs with the GCC front end. Most of these libraries are
1293skeleton versions of real libraries; for example, libc is a stripped down
1294version of glibc.</p>
1295
1296<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1297end to compile.</p>
1298
1299</div>
1300
1301<!-- ======================================================================= -->
1302<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1303<div class="doc_text">
1304 <p>This directory contains feature and regression tests and other basic sanity
1305 checks on the LLVM infrastructure. These are intended to run quickly and cover
1306 a lot of territory without being exhaustive.</p>
1307</div>
1308
1309<!-- ======================================================================= -->
1310<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1311<div class="doc_text">
1312 <p>This is not a directory in the normal llvm module; it is a separate
1313 Subversion
1314 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1315 This
1316 module contains a comprehensive correctness, performance, and benchmarking
1317 test
1318 suite for LLVM. It is a separate Subversion module because not every LLVM
1319 user is
1320 interested in downloading or building such a comprehensive test suite. For
1321 further details on this test suite, please see the
1322 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1323</div>
1324
1325<!-- ======================================================================= -->
1326<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1327<div class="doc_text">
1328
1329<p>The <b>tools</b> directory contains the executables built out of the
1330libraries above, which form the main part of the user interface. You can
1331always get help for a tool by typing <tt>tool_name --help</tt>. The
1332following is a brief introduction to the most important tools. More detailed
1333information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1334
1335<dl>
1336
1337 <dt><tt><b>bugpoint</b></tt></dt>
1338 <dd><tt>bugpoint</tt> is used to debug
1339 optimization passes or code generation backends by narrowing down the
1340 given test case to the minimum number of passes and/or instructions that
1341 still cause a problem, whether it is a crash or miscompilation. See <a
1342 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1343 on using <tt>bugpoint</tt>.</dd>
1344
1345 <dt><tt><b>llvmc</b></tt></dt>
1346 <dd>The LLVM Compiler Driver. This program can
1347 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1348 pre-processing, translation, optimization, assembly, and linking of programs
1349 all from one command line. <tt>llvmc</tt> also takes care of processing the
1350 dependent libraries found in bitcode. This reduces the need to get the
1351 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1352 note that this tool, while functional, is still experimental and not feature
1353 complete.</dd>
1354
1355 <dt><tt><b>llvm-ar</b></tt></dt>
1356 <dd>The archiver produces an archive containing
1357 the given LLVM bitcode files, optionally with an index for faster
1358 lookup.</dd>
1359
1360 <dt><tt><b>llvm-as</b></tt></dt>
1361 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1362 bitcode.</dd>
1363
1364 <dt><tt><b>llvm-dis</b></tt></dt>
1365 <dd>The disassembler transforms the LLVM bitcode to human readable
1366 LLVM assembly.</dd>
1367
1368 <dt><tt><b>llvm-ld</b></tt></dt>
1369 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1370 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1371 optimizations and allows optimization modules to be loaded and run so that
1372 language specific optimizations can be applied at link time.</dd>
1373
1374 <dt><tt><b>llvm-link</b></tt></dt>
1375 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1376 a single program.</dd>
1377
1378 <dt><tt><b>lli</b></tt></dt>
1379 <dd><tt>lli</tt> is the LLVM interpreter, which
1380 can directly execute LLVM bitcode (although very slowly...). In addition
1381 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1382 specifying <tt>-trace</tt> on the command line). Finally, for
1383 architectures that support it (currently x86, Sparc, and PowerPC), by default,
1384 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1385 functionality was compiled in), and will execute the code <i>much</i>
1386 faster than the interpreter.</dd>
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>
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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>