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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 Lattnerf3ff76b2008-04-07 18:32:25 +0000[diff] [blame]117 <li>Install the 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>
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]239 <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]323<li><a name="pf_9">XCode 2.5 and gcc 4.0.1 (Apple Build 5370) will trip
324 internal LLVM assert messages when compiled for Release at optimization
325 levels greater than 0 (i.e., <i>&ldquo;-O1&rdquo;</i> and higher).
326 Add <i>OPTIMIZE_OPTION=&quot;-O0&quot;</i> to the build command line
327 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]328</ol>
329</div>
330
331<p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
332mode, depending on the system (it is so large because of all the debugging
333information and the fact that the libraries are statically linked into multiple
334tools). If you do not need many of the tools and you are space-conscious,
335you can disable them individually in <tt>llvm/tools/Makefile</tt>. The Release
336build requires considerably less space.</p>
337
338<p>The LLVM suite <i>may</i> compile on other platforms, but it is not
339guaranteed to do so. If compilation is successful, the LLVM utilities should be
340able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
341generation should work as well, although the generated native code may not work
342on your platform.</p>
343
344<p>The GCC front end is not very portable at the moment. If you want to get it
345to work on another platform, you can download a copy of the source and <a
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]346href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]347
348</div>
349
350<!-- ======================================================================= -->
351<div class="doc_subsection"><a name="software"><b>Software</b></a></div>
352<div class="doc_text">
353 <p>Compiling LLVM requires that you have several software packages
354 installed. The table below lists those required packages. The Package column
355 is the usual name for the software package that LLVM depends on. The Version
356 column provides "known to work" versions of the package. The Notes column
357 describes how LLVM uses the package and provides other details.</p>
358 <table summary="Packages required to compile LLVM">
359 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
360
361 <tr>
362 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
363 <td>3.79, 3.79.1</td>
364 <td>Makefile/build processor</td>
365 </tr>
366
367 <tr>
368 <td><a href="http://gcc.gnu.org">GCC</a></td>
369 <td>3.4.2</td>
370 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
371 </tr>
372
373 <tr>
374 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
375 <td>4.5</td>
376 <td>For building the CFE</td>
377 </tr>
378
379 <tr>
380 <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
381 <td>2.5.4</td>
382 <td>LEX compiler</td>
383 </tr>
384
385 <tr>
386 <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
387 <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
388 <td>YACC compiler</td>
389 </tr>
390
391 <tr>
392 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
393 <td>&ge;1.3</td>
394 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
395 </tr>
396
397 <tr>
398 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
399 <td>1.4.2</td>
400 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
401 </tr>
402
403 <tr>
404 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
405 <td>8.3, 8.4</td>
406 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
407 </tr>
408
409 <tr>
410 <td><a href="http://expect.nist.gov/">expect</a></td>
411 <td>5.38.0</td>
412 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
413 </tr>
414
415 <tr>
416 <td><a href="http://www.perl.com/download.csp">perl</a></td>
417 <td>&ge;5.6.0</td>
418 <td>Nightly tester, utilities</td>
419 </tr>
420
421 <tr>
422 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
423 <td>1.4</td>
424 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
425 </tr>
426
427 <tr>
428 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
429 <td>2.59</td>
430 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
431 </tr>
432
433 <tr>
434 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
435 <td>1.9.2</td>
436 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
437 </tr>
438
439 <tr>
440 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
441 <td>1.5.10</td>
442 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
443 </tr>
444
445 </table>
446
447 <p><b>Notes:</b></p>
448 <div class="doc_notes">
449 <ol>
450 <li><a name="sf1">Only the C and C++ languages are needed so there's no
451 need to build the other languages for LLVM's purposes.</a> See
452 <a href="#brokengcc">below</a> for specific version info.</li>
453 <li><a name="sf2">You only need Subversion if you intend to build from the
454 latest LLVM sources. If you're working from a release distribution, you
455 don't need Subversion.</a></li>
456 <li><a name="sf3">Only needed if you want to run the automated test
457 suite in the <tt>llvm/test</tt> directory.</a></li>
458 <li><a name="sf4">If you want to make changes to the configure scripts,
459 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
460 or higher). You will also need automake (1.9.2). We only use aclocal
461 from that package.</a></li>
462 </ol>
463 </div>
464
465 <p>Additionally, your compilation host is expected to have the usual
466 plethora of Unix utilities. Specifically:</p>
467 <ul>
468 <li><b>ar</b> - archive library builder</li>
469 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
470 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
471 <li><b>chmod</b> - change permissions on a file</li>
472 <li><b>cat</b> - output concatenation utility</li>
473 <li><b>cp</b> - copy files</li>
474 <li><b>date</b> - print the current date/time </li>
475 <li><b>echo</b> - print to standard output</li>
476 <li><b>egrep</b> - extended regular expression search utility</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]477 <li><b>find</b> - find files/dirs in a file system</li>
478 <li><b>grep</b> - regular expression search utility</li>
479 <li><b>gzip*</b> - gzip command for distribution generation</li>
480 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
481 <li><b>install</b> - install directories/files </li>
482 <li><b>mkdir</b> - create a directory</li>
483 <li><b>mv</b> - move (rename) files</li>
484 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
485 <li><b>rm</b> - remove (delete) files and directories</li>
486 <li><b>sed</b> - stream editor for transforming output</li>
487 <li><b>sh</b> - Bourne shell for make build scripts</li>
488 <li><b>tar</b> - tape archive for distribution generation</li>
489 <li><b>test</b> - test things in file system</li>
490 <li><b>unzip*</b> - unzip command for distribution checking</li>
491 <li><b>zip*</b> - zip command for distribution generation</li>
492 </ul>
493</div>
494
495<!-- ======================================================================= -->
496<div class="doc_subsection">
497 <a name="brokengcc">Broken versions of GCC and other tools</a>
498</div>
499
500<div class="doc_text">
501
502<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
503bugs in the compiler. In particular, several versions of GCC crash when trying
504to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
505successfully with them (however, see important notes below). Other versions
506of GCC will probably work as well. GCC versions listed
507here are known to not work. If you are using one of these versions, please try
508to upgrade your GCC to something more recent. If you run into a problem with a
509version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
510us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
511of GCC you are using.
512</p>
513
514<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
515problems in the STL that effectively prevent it from compiling LLVM.
516</p>
517
Chris Lattner76bb5302008-02-13 17:50:24 +0000[diff] [blame]518<p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
519a bogus template error. This was fixed in later GCCs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]520
521<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
522href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
523the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
524
525<p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]526 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]527 to a newer version</a> if possible.</p>
528<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
529 possibly others) does not compile LLVM correctly (it appears that exception
530 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
531 to a newer version of GCC.</p>
532<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
533 code generator, causing an infinite loop in the llvm-gcc build when built
534 with optimizations enabled (i.e. a release build).</p>
535<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
536 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
537 correctly compiles LLVM at -O2. A work around is to build release LLVM
538 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
539<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
540 miscompiles portions of LLVM</a>.</p>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]541<p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
542 when building with optimizations enabled. It appears to work with
543 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
544 build.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]545<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
546 miscompile LLVM.</p>
547<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
548 default with ENABLE_OPTIMIZED=1. To work around this, build with
549 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
550<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
551 compiling some files. At the time of this writing, GCC mainline (4.2)
552 did not share the problem.</p>
553<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
554 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
555 code. LLVM will appear to mostly work but will be buggy, e.g. failing
556 portions of its testsuite.</p>
557<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
558platforms compiling md5.c gets a mangled constant.</p>
559<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
560long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
561defined in a discarded section. You can safely ignore these messages as they are
562erroneous and the linkage is correct. These messages disappear using ld
5632.17.</p>
564
565<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
566href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
567causes huge link times (minutes instead of seconds) when building LLVM. We
568recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
569
570</div>
571
572
573
574<!-- *********************************************************************** -->
575<div class="doc_section">
576 <a name="starting"><b>Getting Started with LLVM</b></a>
577</div>
578<!-- *********************************************************************** -->
579
580<div class="doc_text">
581
582<p>The remainder of this guide is meant to get you up and running with
583LLVM and to give you some basic information about the LLVM environment.</p>
584
585<p>The later sections of this guide describe the <a
586href="#layout">general layout</a> of the the LLVM source tree, a <a
587href="#tutorial">simple example</a> using the LLVM tool chain, and <a
588href="#links">links</a> to find more information about LLVM or to get
589help via e-mail.</p>
590</div>
591
592<!-- ======================================================================= -->
593<div class="doc_subsection">
594 <a name="terminology">Terminology and Notation</a>
595</div>
596
597<div class="doc_text">
598
599<p>Throughout this manual, the following names are used to denote paths
600specific to the local system and working environment. <i>These are not
601environment variables you need to set but just strings used in the rest
602of this document below</i>. In any of the examples below, simply replace
603each of these names with the appropriate pathname on your local system.
604All these paths are absolute:</p>
605
606<dl>
607 <dt>SRC_ROOT
608 <dd>
609 This is the top level directory of the LLVM source tree.
610 <br><br>
611
612 <dt>OBJ_ROOT
613 <dd>
614 This is the top level directory of the LLVM object tree (i.e. the
615 tree where object files and compiled programs will be placed. It
616 can be the same as SRC_ROOT).
617 <br><br>
618
619 <dt>LLVMGCCDIR
620 <dd>
621 This is where the LLVM GCC Front End is installed.
622 <p>
623 For the pre-built GCC front end binaries, the LLVMGCCDIR is
624 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
625</dl>
626
627</div>
628
629<!-- ======================================================================= -->
630<div class="doc_subsection">
631 <a name="environment">Setting Up Your Environment</a>
632</div>
633
634<div class="doc_text">
635
636<p>
637In order to compile and use LLVM, you may need to set some environment
638variables.
639
640<dl>
641 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
642 <dd>[Optional] This environment variable helps LLVM linking tools find the
643 locations of your bitcode libraries. It is provided only as a
644 convenience since you can specify the paths using the -L options of the
645 tools and the C/C++ front-end will automatically use the bitcode files
646 installed in its
647 <tt>lib</tt> directory.</dd>
648</dl>
649
650</div>
651
652<!-- ======================================================================= -->
653<div class="doc_subsection">
654 <a name="unpack">Unpacking the LLVM Archives</a>
655</div>
656
657<div class="doc_text">
658
659<p>
660If you have the LLVM distribution, you will need to unpack it before you
661can begin to compile it. LLVM is distributed as a set of two files: the LLVM
662suite and the LLVM GCC front end compiled for your platform. There is an
663additional test suite that is optional. Each file is a TAR archive that is
664compressed with the gzip program.
665</p>
666
667<p>The files are as follows, with <em>x.y</em> marking the version number:
668<dl>
669 <dt><tt>llvm-x.y.tar.gz</tt></dt>
670 <dd>Source release for the LLVM libraries and tools.<br/></dd>
671
672 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
673 <dd>Source release for the LLVM test suite.</dd>
674
675 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
676 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
677 directory for build instructions.<br/></dd>
678
679 <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
680 <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
681
682</dl>
683
684<p>It is also possible to download the sources of the llvm-gcc4 front end from a
685read-only subversion mirror at
686svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
687
688</div>
689
690<!-- ======================================================================= -->
691<div class="doc_subsection">
692 <a name="checkout">Checkout LLVM from Subversion</a>
693</div>
694
695<div class="doc_text">
696
697<p>If you have access to our Subversion repository, you can get a fresh copy of
698the entire source code. All you need to do is check it out from Subvresion as
699follows:</p>
700
701<ul>
702 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
703 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
704 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
705 llvm</tt></li>
706</ul>
707
708
709<p>This will create an '<tt>llvm</tt>' directory in the current
710directory and fully populate it with the LLVM source code, Makefiles,
711test directories, and local copies of documentation files.</p>
712
713<p>If you want to get a specific release (as opposed to the most recent
714revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
715'<tt>trunk</tt>'). The following releases are located in the following
716 subdirectories of the '<tt>tags</tt>' directory:</p>
717
718<ul>
Tanya Lattner9eb3be52008-06-09 06:02:09 +0000[diff] [blame^]719<li>Release 2.3: <b>RELEASE_23</b></li>
Tanya Lattner60030782008-02-12 02:42:55 +0000[diff] [blame]720<li>Release 2.2: <b>RELEASE_22</b></li>
Tanya Lattner2fad5b02007-09-28 22:50:54 +0000[diff] [blame]721<li>Release 2.1: <b>RELEASE_21</b></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]722<li>Release 2.0: <b>RELEASE_20</b></li>
723<li>Release 1.9: <b>RELEASE_19</b></li>
724<li>Release 1.8: <b>RELEASE_18</b></li>
725<li>Release 1.7: <b>RELEASE_17</b></li>
726<li>Release 1.6: <b>RELEASE_16</b></li>
727<li>Release 1.5: <b>RELEASE_15</b></li>
728<li>Release 1.4: <b>RELEASE_14</b></li>
729<li>Release 1.3: <b>RELEASE_13</b></li>
730<li>Release 1.2: <b>RELEASE_12</b></li>
731<li>Release 1.1: <b>RELEASE_11</b></li>
732<li>Release 1.0: <b>RELEASE_1</b></li>
733</ul>
734
735<p>If you would like to get the LLVM test suite (a separate package as of 1.4),
736you get it from the Subversion repository:</p>
737
738<div class="doc_code">
739<pre>
740% cd llvm/projects
741% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
742</pre>
743</div>
744
745<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
746configured by the LLVM configure script as well as automatically updated when
747you run <tt>svn update</tt>.</p>
748
749<p>If you would like to get the GCC front end source code, you can also get it
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]750and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]751instructions</a> to successfully get and build the LLVM GCC front-end.</p>
752
753</div>
754
755<!-- ======================================================================= -->
756<div class="doc_subsection">
757 <a name="installcf">Install the GCC Front End</a>
758</div>
759
760<div class="doc_text">
761
762<p>Before configuring and compiling the LLVM suite, you can optionally extract the
763LLVM GCC front end from the binary distribution. It is used for running the
764llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]765<a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]766main LLVM repository.</p>
767
768<p>To install the GCC front end, do the following:</p>
769
770<ol>
771 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
772 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
773 -</tt></li>
774</ol>
775
776<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
777llvm-g++ to some directory in your path. When you configure LLVM, it will
778automatically detect llvm-gcc's presence (if it is in your path) enabling its
779use in llvm-test. Note that you can always build or install llvm-gcc at any
780pointer after building the main LLVM repository: just reconfigure llvm and
781llvm-test will pick it up.
782</p>
783
784<p>The binary versions of the GCC front end may not suit all of your needs. For
785example, the binary distribution may include an old version of a system header
786file, not "fix" a header file that needs to be fixed for GCC, or it may be
787linked with libraries not available on your system.</p>
788
789<p>In cases like these, you may want to try <a
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]790href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]791much easier now than it was in the past.</p>
792
793</div>
794
795<!-- ======================================================================= -->
796<div class="doc_subsection">
797 <a name="config">Local LLVM Configuration</a>
798</div>
799
800<div class="doc_text">
801
802 <p>Once checked out from the Subversion repository, the LLVM suite source
803 code must be
804configured via the <tt>configure</tt> script. This script sets variables in the
805various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
806<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
807the Makefiles needed to begin building LLVM.</p>
808
809<p>The following environment variables are used by the <tt>configure</tt>
810script to configure the build system:</p>
811
812<table summary="LLVM configure script environment variables">
813 <tr><th>Variable</th><th>Purpose</th></tr>
814 <tr>
815 <td>CC</td>
816 <td>Tells <tt>configure</tt> which C compiler to use. By default,
817 <tt>configure</tt> will look for the first GCC C compiler in
818 <tt>PATH</tt>. Use this variable to override
819 <tt>configure</tt>'s default behavior.</td>
820 </tr>
821 <tr>
822 <td>CXX</td>
823 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
824 <tt>configure</tt> will look for the first GCC C++ compiler in
825 <tt>PATH</tt>. Use this variable to override
826 <tt>configure</tt>'s default behavior.</td>
827 </tr>
828</table>
829
830<p>The following options can be used to set or enable LLVM specific options:</p>
831
832<dl>
833 <dt><i>--with-llvmgccdir</i></dt>
834 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
835 The value of this option should specify the full pathname of the C/C++ Front
836 End to be used. If this option is not provided, the PATH will be searched for
837 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
838 be inferred from the path found. If the option is not given, and no llvm-gcc
839 can be found in the path then a warning will be produced by
840 <tt>configure</tt> indicating this situation. LLVM may still be built with
841 the <tt>tools-only</tt> target but attempting to build the runtime libraries
842 will fail as these libraries require llvm-gcc and llvm-g++. See
843 <a href="#installcf">Install the GCC Front End</a> for details on installing
844 the C/C++ Front End. See
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]845 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]846 for details on building the C/C++ Front End.</dd>
847 <dt><i>--with-tclinclude</i></dt>
848 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
849 found. Use this if you have multiple tcl installations on your machine and you
850 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
851 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
852 option, the LLVM configure script will search for the tcl 8.4 and 8.3
853 releases.
854 <br><br>
855 </dd>
856 <dt><i>--enable-optimized</i></dt>
857 <dd>
858 Enables optimized compilation by default (debugging symbols are removed
859 and GCC optimization flags are enabled). The default is to use an
860 unoptimized build (also known as a debug build).
861 <br><br>
862 </dd>
863 <dt><i>--enable-debug-runtime</i></dt>
864 <dd>
865 Enables debug symbols in the runtime libraries. The default is to strip
866 debug symbols from the runtime libraries.
867 </dd>
868 <dt><i>--enable-jit</i></dt>
869 <dd>
870 Compile the Just In Time (JIT) compiler functionality. This is not
871 available
872 on all platforms. The default is dependent on platform, so it is best
873 to explicitly enable it if you want it.
874 <br><br>
875 </dd>
876 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
877 <dd>Controls which targets will be built and linked into llc. The default
878 value for <tt>target_options</tt> is "all" which builds and links all
879 available targets. The value "host-only" can be specified to build only a
880 native compiler (no cross-compiler targets available). The "native" target is
881 selected as the target of the build host. You can also specify a comma
882 separated list of target names that you want available in llc. The target
883 names use all lower case. The current set of targets is: <br/>
884 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
885 <br><br></dd>
886 <dt><i>--enable-doxygen</i></dt>
887 <dd>Look for the doxygen program and enable construction of doxygen based
888 documentation from the source code. This is disabled by default because
889 generating the documentation can take a long time and producess 100s of
890 megabytes of output.</dd>
891 <dt><i>--with-udis86</i></dt>
892 <dd>LLVM can use external disassembler library for various purposes (now it's
893 used only for examining code produced by JIT). This option will enable usage
894 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
895 bits) disassembler library.</dd>
896</dl>
897
898<p>To configure LLVM, follow these steps:</p>
899
900<ol>
901 <li><p>Change directory into the object root directory:</p>
902
903 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
904
905 <li><p>Run the <tt>configure</tt> script located in the LLVM source
906 tree:</p>
907
908 <div class="doc_code">
909 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
910 </div></li>
911</ol>
912
913</div>
914
915<!-- ======================================================================= -->
916<div class="doc_subsection">
917 <a name="compile">Compiling the LLVM Suite Source Code</a>
918</div>
919
920<div class="doc_text">
921
922<p>Once you have configured LLVM, you can build it. There are three types of
923builds:</p>
924
925<dl>
926 <dt>Debug Builds
927 <dd>
928 These builds are the default when one types <tt>gmake</tt> (unless the
929 <tt>--enable-optimized</tt> option was used during configuration). The
930 build system will compile the tools and libraries with debugging
931 information.
932 <br><br>
933
934 <dt>Release (Optimized) Builds
935 <dd>
936 These builds are enabled with the <tt>--enable-optimized</tt> option to
937 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
938 <tt>gmake</tt> command line. For these builds, the build system will
939 compile the tools and libraries with GCC optimizations enabled and strip
940 debugging information from the libraries and executables it generates.
941 <br><br>
942
943 <dt>Profile Builds
944 <dd>
945 These builds are for use with profiling. They compile profiling
946 information into the code for use with programs like <tt>gprof</tt>.
947 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
948 on the <tt>gmake</tt> command line.
949</dl>
950
951<p>Once you have LLVM configured, you can build it by entering the
952<i>OBJ_ROOT</i> directory and issuing the following command:</p>
953
954<div class="doc_code"><pre>% gmake</pre></div>
955
956<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
957are using a version of GCC that is known not to compile LLVM.</p>
958
959<p>
960If you have multiple processors in your machine, you may wish to use some of
961the parallel build options provided by GNU Make. For example, you could use the
962command:</p>
963
964<div class="doc_code"><pre>% gmake -j2</pre></div>
965
966<p>There are several special targets which are useful when working with the LLVM
967source code:</p>
968
969<dl>
970 <dt><tt>gmake clean</tt>
971 <dd>
972 Removes all files generated by the build. This includes object files,
973 generated C/C++ files, libraries, and executables.
974 <br><br>
975
976 <dt><tt>gmake dist-clean</tt>
977 <dd>
978 Removes everything that <tt>gmake clean</tt> does, but also removes files
979 generated by <tt>configure</tt>. It attempts to return the source tree to the
980 original state in which it was shipped.
981 <br><br>
982
983 <dt><tt>gmake install</tt>
984 <dd>
985 Installs LLVM header files, libraries, tools, and documentation in a
986 hierarchy
987 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
988 defaults to <tt>/usr/local</tt>.
989 <br><br>
990
991 <dt><tt>gmake -C runtime install-bytecode</tt>
992 <dd>
993 Assuming you built LLVM into $OBJDIR, when this command is run, it will
994 install bitcode libraries into the GCC front end's bitcode library
995 directory. If you need to update your bitcode libraries,
996 this is the target to use once you've built them.
997 <br><br>
998</dl>
999
1000<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1001details on these <tt>make</tt> targets and descriptions of other targets
1002available.</p>
1003
1004<p>It is also possible to override default values from <tt>configure</tt> by
1005declaring variables on the command line. The following are some examples:</p>
1006
1007<dl>
1008 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1009 <dd>
1010 Perform a Release (Optimized) build.
1011 <br><br>
1012
1013 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1014 <dd>
1015 Perform a Release (Optimized) build without assertions enabled.
1016 <br><br>
1017
1018 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1019 <dd>
1020 Perform a Profiling build.
1021 <br><br>
1022
1023 <dt><tt>gmake VERBOSE=1</tt>
1024 <dd>
1025 Print what <tt>gmake</tt> is doing on standard output.
1026 <br><br>
1027
1028 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1029 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1030 the standard output. This also implies <tt>VERBOSE=1</tt>.
1031 <br><br></dd>
1032</dl>
1033
1034<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1035it and any subdirectories that it contains. Entering any directory inside the
1036LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1037that directory that is out of date.</p>
1038
1039</div>
1040
1041<!-- ======================================================================= -->
1042<div class="doc_subsection">
1043 <a name="cross-compile">Cross-Compiling LLVM</a>
1044</div>
1045
1046<div class="doc_text">
1047 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1048 executables and libraries for a platform different than the one one which you
1049 are compiling. To do this, a few additional steps are
1050 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1051 these instructions:</p>
1052 <ol>
1053 <li>Configure and build LLVM as a native compiler. You will need
1054 just <tt>TableGen</tt> from that build.
1055 <ul>
1056 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1057 <tt>make -C utils/TableGen</tt> after configuring.</li>
1058 <li>Otherwise you will need to monitor building process and terminate
1059 it just after <tt>TableGen</tt> was built.</li>
1060 </ul>
1061 </li>
1062 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1063 </li>
1064 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1065 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1066 are different. The values of these options must be legal target triples
1067 that your GCC compiler supports.</li>
1068 <li>Put the saved <tt>TableGen</tt> executable into the
1069 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1070 <tt>.../Release/bin</tt> for a Release build).</li>
1071 <li>Build LLVM as usual.</li>
1072 </ol>
1073 <p>The result of such a build will produce executables that are not executable
1074 on your build host (--build option) but can be executed on your compile host
1075 (--host option).</p>
1076 <p><b>Notes:</b></p>
1077 <div class="doc_notes">
1078 <ol>
1079 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1080 build platform and Windows as host using mingw32 cross-compiler. Other
1081 combinations have not been tested.</li>
1082 </ol>
1083 </div>
1084</div>
1085
1086<!-- ======================================================================= -->
1087<div class="doc_subsection">
1088 <a name="objfiles">The Location of LLVM Object Files</a>
1089</div>
1090
1091<div class="doc_text">
1092
1093<p>The LLVM build system is capable of sharing a single LLVM source tree among
1094several LLVM builds. Hence, it is possible to build LLVM for several different
1095platforms or configurations using the same source tree.</p>
1096
1097<p>This is accomplished in the typical autoconf manner:</p>
1098
1099<ul>
1100 <li><p>Change directory to where the LLVM object files should live:</p>
1101
1102 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1103
1104 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1105 directory:</p>
1106
1107 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1108</ul>
1109
1110<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1111named after the build type:</p>
1112
1113<dl>
1114 <dt>Debug Builds
1115 <dd>
1116 <dl>
1117 <dt>Tools
1118 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1119 <dt>Libraries
1120 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1121 </dl>
1122 <br><br>
1123
1124 <dt>Release Builds
1125 <dd>
1126 <dl>
1127 <dt>Tools
1128 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1129 <dt>Libraries
1130 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1131 </dl>
1132 <br><br>
1133
1134 <dt>Profile Builds
1135 <dd>
1136 <dl>
1137 <dt>Tools
1138 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1139 <dt>Libraries
1140 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1141 </dl>
1142</dl>
1143
1144</div>
1145
1146<!-- ======================================================================= -->
1147<div class="doc_subsection">
1148 <a name="optionalconfig">Optional Configuration Items</a>
1149</div>
1150
1151<div class="doc_text">
1152
1153<p>
1154If you're running on a Linux system that supports the "<a
1155href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1156module, and you have root access on the system, you can set your system up to
1157execute LLVM bitcode files directly. To do this, use commands like this (the
1158first command may not be required if you are already using the module):</p>
1159
1160<div class="doc_code">
1161<pre>
1162$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1163$ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1164$ chmod u+x hello.bc (if needed)
1165$ ./hello.bc
1166</pre>
1167</div>
1168
1169<p>
1170This allows you to execute LLVM bitcode files directly. Thanks to Jack
1171Cummings for pointing this out!
1172</p>
1173
1174</div>
1175
1176
1177<!-- *********************************************************************** -->
1178<div class="doc_section">
1179 <a name="layout"><b>Program Layout</b></a>
1180</div>
1181<!-- *********************************************************************** -->
1182
1183<div class="doc_text">
1184
1185<p>One useful source of information about the LLVM source base is the LLVM <a
1186href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1187href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1188The following is a brief introduction to code layout:</p>
1189
1190</div>
1191
1192<!-- ======================================================================= -->
1193<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1194<div class="doc_text">
1195 <p>This directory contains some simple examples of how to use the LLVM IR and
1196 JIT.</p>
1197</div>
1198
1199<!-- ======================================================================= -->
1200<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1201<div class="doc_text">
1202
1203<p>This directory contains public header files exported from the LLVM
1204library. The three main subdirectories of this directory are:</p>
1205
1206<dl>
1207 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1208 <dd>This directory contains all of the LLVM specific header files. This
1209 directory also has subdirectories for different portions of LLVM:
1210 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1211 etc...</dd>
1212
1213 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1214 <dd>This directory contains generic support libraries that are provided with
1215 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1216 and a Command Line option processing library store their header files here.
1217 </dd>
1218
1219 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1220 <dd>This directory contains header files configured by the <tt>configure</tt>
1221 script. They wrap "standard" UNIX and C header files. Source code can
1222 include these header files which automatically take care of the conditional
1223 #includes that the <tt>configure</tt> script generates.</dd>
1224</dl>
1225</div>
1226
1227<!-- ======================================================================= -->
1228<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1229<div class="doc_text">
1230
1231<p>This directory contains most of the source files of the LLVM system. In LLVM,
1232almost all code exists in libraries, making it very easy to share code among the
1233different <a href="#tools">tools</a>.</p>
1234
1235<dl>
1236 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1237 <dd> This directory holds the core LLVM source files that implement core
1238 classes like Instruction and BasicBlock.</dd>
1239
1240 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1241 <dd>This directory holds the source code for the LLVM assembly language parser
1242 library.</dd>
1243
1244 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1245 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1246
1247 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1248 different program analyses, such as Dominator Information, Call Graphs,
1249 Induction Variables, Interval Identification, Natural Loop Identification,
1250 etc.</dd>
1251
1252 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1253 <dd> This directory contains the source code for the LLVM to LLVM program
1254 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1255 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1256 Elimination, and many others.</dd>
1257
1258 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1259 <dd> This directory contains files that describe various target architectures
1260 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1261 directory holds the X86 machine description while
1262 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1263
1264 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1265 <dd> This directory contains the major parts of the code generator: Instruction
1266 Selector, Instruction Scheduling, and Register Allocation.</dd>
1267
1268 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1269 <dd> This directory contains the source level debugger library that makes
1270 it possible to instrument LLVM programs so that a debugger could identify
1271 source code locations at which the program is executing.</dd>
1272
1273 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1274 <dd> This directory contains libraries for executing LLVM bitcode directly
1275 at runtime in both interpreted and JIT compiled fashions.</dd>
1276
1277 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1278 <dd> This directory contains the source code that corresponds to the header
1279 files located in <tt>llvm/include/Support/</tt>.</dd>
1280
1281 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1282 <dd>This directory contains the operating system abstraction layer that
1283 shields LLVM from platform-specific coding.</dd>
1284</dl>
1285
1286</div>
1287
1288<!-- ======================================================================= -->
1289<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1290<div class="doc_text">
1291 <p>This directory contains projects that are not strictly part of LLVM but are
1292 shipped with LLVM. This is also the directory where you should create your own
1293 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1294 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1295 functional example of a compiler front end.</p>
1296</div>
1297
1298<!-- ======================================================================= -->
1299<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1300<div class="doc_text">
1301
1302<p>This directory contains libraries which are compiled into LLVM bitcode and
1303used when linking programs with the GCC front end. Most of these libraries are
1304skeleton versions of real libraries; for example, libc is a stripped down
1305version of glibc.</p>
1306
1307<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1308end to compile.</p>
1309
1310</div>
1311
1312<!-- ======================================================================= -->
1313<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1314<div class="doc_text">
1315 <p>This directory contains feature and regression tests and other basic sanity
1316 checks on the LLVM infrastructure. These are intended to run quickly and cover
1317 a lot of territory without being exhaustive.</p>
1318</div>
1319
1320<!-- ======================================================================= -->
1321<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1322<div class="doc_text">
1323 <p>This is not a directory in the normal llvm module; it is a separate
1324 Subversion
1325 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1326 This
1327 module contains a comprehensive correctness, performance, and benchmarking
1328 test
1329 suite for LLVM. It is a separate Subversion module because not every LLVM
1330 user is
1331 interested in downloading or building such a comprehensive test suite. For
1332 further details on this test suite, please see the
1333 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1334</div>
1335
1336<!-- ======================================================================= -->
1337<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1338<div class="doc_text">
1339
1340<p>The <b>tools</b> directory contains the executables built out of the
1341libraries above, which form the main part of the user interface. You can
1342always get help for a tool by typing <tt>tool_name --help</tt>. The
1343following is a brief introduction to the most important tools. More detailed
1344information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1345
1346<dl>
1347
1348 <dt><tt><b>bugpoint</b></tt></dt>
1349 <dd><tt>bugpoint</tt> is used to debug
1350 optimization passes or code generation backends by narrowing down the
1351 given test case to the minimum number of passes and/or instructions that
1352 still cause a problem, whether it is a crash or miscompilation. See <a
1353 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1354 on using <tt>bugpoint</tt>.</dd>
1355
1356 <dt><tt><b>llvmc</b></tt></dt>
1357 <dd>The LLVM Compiler Driver. This program can
1358 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1359 pre-processing, translation, optimization, assembly, and linking of programs
1360 all from one command line. <tt>llvmc</tt> also takes care of processing the
1361 dependent libraries found in bitcode. This reduces the need to get the
1362 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1363 note that this tool, while functional, is still experimental and not feature
1364 complete.</dd>
1365
1366 <dt><tt><b>llvm-ar</b></tt></dt>
1367 <dd>The archiver produces an archive containing
1368 the given LLVM bitcode files, optionally with an index for faster
1369 lookup.</dd>
1370
1371 <dt><tt><b>llvm-as</b></tt></dt>
1372 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1373 bitcode.</dd>
1374
1375 <dt><tt><b>llvm-dis</b></tt></dt>
1376 <dd>The disassembler transforms the LLVM bitcode to human readable
1377 LLVM assembly.</dd>
1378
1379 <dt><tt><b>llvm-ld</b></tt></dt>
1380 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1381 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1382 optimizations and allows optimization modules to be loaded and run so that
1383 language specific optimizations can be applied at link time.</dd>
1384
1385 <dt><tt><b>llvm-link</b></tt></dt>
1386 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1387 a single program.</dd>
1388
1389 <dt><tt><b>lli</b></tt></dt>
1390 <dd><tt>lli</tt> is the LLVM interpreter, which
Nick Lewycky32dc2a12007-12-03 01:58:01 +0000[diff] [blame]1391 can directly execute LLVM bitcode (although very slowly...). For architectures
1392 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1393 will function as a Just-In-Time compiler (if the functionality was compiled
1394 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1395
1396 <dt><tt><b>llc</b></tt></dt>
1397 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1398 translates LLVM bitcode to a native code assembly file or to C code (with
1399 the -march=c option).</dd>
1400
1401 <dt><tt><b>llvm-gcc</b></tt></dt>
1402 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1403 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1404 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1405 usual machine code output. It works just like any other GCC compiler,
1406 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1407 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1408 separate Subversion module.</dd>
1409
1410 <dt><tt><b>opt</b></tt></dt>
1411 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1412 transformations (which are specified on the command line), and then outputs
1413 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1414 get a list of the program transformations available in LLVM.<br/>
1415 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1416 LLVM bitcode file and print out the results. It is primarily useful for
1417 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1418</dl>
1419</div>
1420
1421<!-- ======================================================================= -->
1422<div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1423<div class="doc_text">
1424
1425<p>This directory contains utilities for working with LLVM source code, and some
1426of the utilities are actually required as part of the build process because they
1427are code generators for parts of LLVM infrastructure.</p>
1428
1429<dl>
1430 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1431 that finds differences between code that LLC generates and code that LLI
1432 generates. This is a useful tool if you are debugging one of them,
1433 assuming that the other generates correct output. For the full user
1434 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1435
1436 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1437 syntax-highlighting files which will work with Emacs and XEmacs editors,
1438 providing syntax highlighting support for LLVM assembly files and TableGen
1439 description files. For information on how to use the syntax files, consult
1440 the <tt>README</tt> file in that directory.<br><br>
1441
1442 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1443 and outputs all non-generated source files, which is useful if one wishes
1444 to do a lot of development across directories and does not want to
1445 individually find each file. One way to use it is to run, for example:
1446 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1447 tree.<br><br>
1448
1449 <dt><tt><b>llvmgrep</b></tt></dt>
1450 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1451 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1452 line. This is a very efficient way of searching the source base for a
1453 particular regular expression.</dd>
1454
1455 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1456 files in the current directory and then compiles and links the tool that
1457 is the first argument. For example, assuming you are in the directory
1458 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1459 simply running <tt>makellvm llc</tt> will make a build of the current
1460 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1461 causing a re-linking of LLC.<br><br>
1462
1463 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1464 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1465 cron script to generate nightly status reports of the functionality of
1466 tools, and the results can be seen by following the appropriate link on
1467 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1468
1469 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1470 the tool used to generate register descriptions, instruction set
1471 descriptions, and even assemblers from common TableGen description
1472 files.<br><br>
1473
1474 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1475 syntax-highlighting files which will work with the VIM editor, providing
1476 syntax highlighting support for LLVM assembly files and TableGen
1477 description files. For information on how to use the syntax files, consult
1478 the <tt>README</tt> file in that directory.<br><br>
1479
1480</dl>
1481
1482</div>
1483
1484<!-- ======================================================================= -->
1485<div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1486<div class="doc_text">
1487 <p>This directory contains build scripts and project files for use with
1488 Visual C++. This allows developers on Windows to build LLVM without the need
1489 for Cygwin. The contents of this directory should be considered experimental
1490 at this time.
1491 </p>
1492</div>
1493<!-- *********************************************************************** -->
1494<div class="doc_section">
1495 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1496</div>
1497<!-- *********************************************************************** -->
1498
1499<div class="doc_text">
1500<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1501so we only include instructiosn for llvm-gcc4.
1502</p>
1503
1504<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1505from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1506create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1507the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1508<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1509output.</p>
1510</div>
1511
1512<!-- ======================================================================= -->
1513<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1514
1515<div class="doc_text">
1516
1517<ol>
1518 <li><p>First, create a simple C file, name it 'hello.c':</p>
1519
1520<div class="doc_code">
1521<pre>
1522#include &lt;stdio.h&gt;
1523
1524int main() {
1525 printf("hello world\n");
1526 return 0;
1527}
1528</pre></div></li>
1529
1530 <li><p>Next, compile the C file into a native executable:</p>
1531
1532 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1533
1534 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1535 -c arguments work as usual (producing a native .s or .o file,
1536 respectively).</p></li>
1537
1538 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1539
1540 <div class="doc_code">
1541 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1542
1543 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1544 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1545 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1546 the bitcode file.</p>
1547
1548 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1549 </p></li>
1550
1551 <li><p>Run the program in both forms. To run the program, use:</p>
1552
1553 <div class="doc_code"><pre>% ./hello</pre></div>
1554
1555 <p>and</p>
1556
1557 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1558
1559 <p>The second examples shows how to invoke the LLVM JIT, <a
1560 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1561
1562 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1563 code:</p>
1564
1565<div class="doc_code">
1566<pre>llvm-dis &lt; hello.bc | less</pre>
1567</div></li>
1568
1569 <li><p>Compile the program to native assembly using the LLC code
1570 generator:</p>
1571
1572 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1573
1574 <li><p>Assemble the native assembly language file into a program:</p>
1575
1576<div class="doc_code">
1577<pre>
1578<b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1579
1580<b>Others:</b> % gcc hello.s -o hello.native
1581</pre>
1582</div></li>
1583
1584 <li><p>Execute the native code program:</p>
1585
1586 <div class="doc_code"><pre>% ./hello.native</pre></div>
1587
1588 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1589 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1590 </li>
1591
1592</ol>
1593
1594</div>
1595
1596
1597<!-- *********************************************************************** -->
1598<div class="doc_section">
1599 <a name="problems">Common Problems</a>
1600</div>
1601<!-- *********************************************************************** -->
1602
1603<div class="doc_text">
1604
1605<p>If you are having problems building or using LLVM, or if you have any other
1606general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1607Asked Questions</a> page.</p>
1608
1609</div>
1610
1611<!-- *********************************************************************** -->
1612<div class="doc_section">
1613 <a name="links">Links</a>
1614</div>
1615<!-- *********************************************************************** -->
1616
1617<div class="doc_text">
1618
1619<p>This document is just an <b>introduction</b> to how to use LLVM to do
1620some simple things... there are many more interesting and complicated things
1621that you can do that aren't documented here (but we'll gladly accept a patch
1622if you want to write something up!). For more information about LLVM, check
1623out:</p>
1624
1625<ul>
1626 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1627 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1628 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1629 that Uses LLVM</a></li>
1630</ul>
1631
1632</div>
1633
1634<!-- *********************************************************************** -->
1635
1636<hr>
1637<address>
1638 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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1641 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
1642
1643 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1644 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1645 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1646 Last modified: $Date$
1647</address>
1648</body>
1649</html>