Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / 30403a0a6c6fe3e0a79aa476b833d27acfbbd037 / . / docs / GettingStarted.html
blob: 1cca5ac8e0910073a4ceb501f893f04eac70ddf8 [file] [log] [blame]
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <title>Getting Started with LLVM System</title>
7 <link rel="stylesheet" href="llvm.css" type="text/css">
8</head>
9<body>
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>
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]117 <li>Install the llvm-gcc-4.2 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>
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]120 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]121 </li>
Chris Lattnerfdae8682008-11-09 17:19:14 +0000[diff] [blame]122 <li>Note: If the binary extension is ".bz" use bunzip2 instead of gunzip.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]123 <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
124 </ol></li>
125
126 <li>Get the LLVM Source Code
127 <ul>
128 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
129 <ol>
130 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
131 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
132 </ol></li>
133
134 </ul></li>
135
136 <li><b>[Optional]</b> Get the Test Suite Source Code
137 <ul>
138 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
139 <ol>
140 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
141 <li><tt>cd llvm/projects</tt>
142 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
143 </ol></li>
144
145 </ul></li>
146
147
148 <li>Configure the LLVM Build Environment
149 <ol>
150 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
151 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
152 Some common options:
153
154 <ul>
155 <li><tt>--prefix=<i>directory</i></tt>
156 <p>Specify for <i>directory</i> the full pathname of where you
157 want the LLVM tools and libraries to be installed (default
158 <tt>/usr/local</tt>).</p></li>
159 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
160 <p>Optionally, specify for <i>directory</i> the full pathname of the
161 C/C++ front end installation to use with this LLVM configuration. If
Duncan Sandscff3d042009-04-18 12:40:19 +0000[diff] [blame]162 not specified, the PATH will be searched. This is only needed if you
163 want to run the testsuite or do some special kinds of LLVM builds.</p></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
Dan Gohman99fc2442008-11-13 19:07:07 +0000[diff] [blame]256 <td>amd64</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
Nick Lewycky18b90af2008-12-08 00:45:02 +0000[diff] [blame]272 <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
Nick Lewycky18b90af2008-12-08 00:45:02 +0000[diff] [blame]309<li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]310<li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
Chris Lattner789ce3a2009-01-02 07:10:51 +0000[diff] [blame]311<li><a name="pf_6">The port is done using the MSYS shell.</a></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]312<li><a name="pf_7">Native code generation exists but is not complete.</a></li>
313<li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
314 preventing LLVM from building correctly. Several workarounds have been
315 introduced into LLVM build system, but the bug can occur anytime in the
316 future. We highly recommend that you rebuild your current binutils with the
317 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
318 Binutils bugzilla</a>, if it wasn't already applied.</li>
Chris Lattnerfdae8682008-11-09 17:19:14 +0000[diff] [blame]319<li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]320 internal LLVM assert messages when compiled for Release at optimization
Chris Lattnerfdae8682008-11-09 17:19:14 +0000[diff] [blame]321 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
322 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]323 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]324</ol>
325</div>
326
327<p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
328mode, depending on the system (it is so large because of all the debugging
329information and the fact that the libraries are statically linked into multiple
Chris Lattner15aeb9a2009-04-25 22:08:52 +0000[diff] [blame]330tools). If you do not need many of the tools and you are space-conscious, you
331can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
332requires considerably less space.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]333
334<p>The LLVM suite <i>may</i> compile on other platforms, but it is not
335guaranteed to do so. If compilation is successful, the LLVM utilities should be
336able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
337generation should work as well, although the generated native code may not work
338on your platform.</p>
339
340<p>The GCC front end is not very portable at the moment. If you want to get it
341to work on another platform, you can download a copy of the source and <a
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]342href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]343
344</div>
345
346<!-- ======================================================================= -->
347<div class="doc_subsection"><a name="software"><b>Software</b></a></div>
348<div class="doc_text">
349 <p>Compiling LLVM requires that you have several software packages
350 installed. The table below lists those required packages. The Package column
351 is the usual name for the software package that LLVM depends on. The Version
352 column provides "known to work" versions of the package. The Notes column
353 describes how LLVM uses the package and provides other details.</p>
354 <table summary="Packages required to compile LLVM">
355 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
356
357 <tr>
358 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
359 <td>3.79, 3.79.1</td>
360 <td>Makefile/build processor</td>
361 </tr>
362
363 <tr>
364 <td><a href="http://gcc.gnu.org">GCC</a></td>
365 <td>3.4.2</td>
366 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
367 </tr>
368
369 <tr>
370 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
371 <td>4.5</td>
372 <td>For building the CFE</td>
373 </tr>
374
375 <tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]376 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
377 <td>&ge;1.3</td>
378 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
379 </tr>
380
381 <tr>
382 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
383 <td>1.4.2</td>
384 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
385 </tr>
386
387 <tr>
388 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
389 <td>8.3, 8.4</td>
390 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
391 </tr>
392
393 <tr>
394 <td><a href="http://expect.nist.gov/">expect</a></td>
395 <td>5.38.0</td>
396 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
397 </tr>
398
399 <tr>
400 <td><a href="http://www.perl.com/download.csp">perl</a></td>
401 <td>&ge;5.6.0</td>
402 <td>Nightly tester, utilities</td>
403 </tr>
404
405 <tr>
406 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
407 <td>1.4</td>
408 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
409 </tr>
410
411 <tr>
412 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
413 <td>2.59</td>
414 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
415 </tr>
416
417 <tr>
418 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
419 <td>1.9.2</td>
420 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
421 </tr>
422
423 <tr>
424 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
425 <td>1.5.10</td>
426 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
427 </tr>
428
429 </table>
430
431 <p><b>Notes:</b></p>
432 <div class="doc_notes">
433 <ol>
434 <li><a name="sf1">Only the C and C++ languages are needed so there's no
435 need to build the other languages for LLVM's purposes.</a> See
436 <a href="#brokengcc">below</a> for specific version info.</li>
437 <li><a name="sf2">You only need Subversion if you intend to build from the
438 latest LLVM sources. If you're working from a release distribution, you
439 don't need Subversion.</a></li>
440 <li><a name="sf3">Only needed if you want to run the automated test
441 suite in the <tt>llvm/test</tt> directory.</a></li>
442 <li><a name="sf4">If you want to make changes to the configure scripts,
443 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
444 or higher). You will also need automake (1.9.2). We only use aclocal
445 from that package.</a></li>
446 </ol>
447 </div>
448
449 <p>Additionally, your compilation host is expected to have the usual
450 plethora of Unix utilities. Specifically:</p>
451 <ul>
452 <li><b>ar</b> - archive library builder</li>
453 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
454 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
455 <li><b>chmod</b> - change permissions on a file</li>
456 <li><b>cat</b> - output concatenation utility</li>
457 <li><b>cp</b> - copy files</li>
458 <li><b>date</b> - print the current date/time </li>
459 <li><b>echo</b> - print to standard output</li>
460 <li><b>egrep</b> - extended regular expression search utility</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]461 <li><b>find</b> - find files/dirs in a file system</li>
462 <li><b>grep</b> - regular expression search utility</li>
463 <li><b>gzip*</b> - gzip command for distribution generation</li>
464 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
465 <li><b>install</b> - install directories/files </li>
466 <li><b>mkdir</b> - create a directory</li>
467 <li><b>mv</b> - move (rename) files</li>
468 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
469 <li><b>rm</b> - remove (delete) files and directories</li>
470 <li><b>sed</b> - stream editor for transforming output</li>
471 <li><b>sh</b> - Bourne shell for make build scripts</li>
472 <li><b>tar</b> - tape archive for distribution generation</li>
473 <li><b>test</b> - test things in file system</li>
474 <li><b>unzip*</b> - unzip command for distribution checking</li>
475 <li><b>zip*</b> - zip command for distribution generation</li>
476 </ul>
477</div>
478
479<!-- ======================================================================= -->
480<div class="doc_subsection">
481 <a name="brokengcc">Broken versions of GCC and other tools</a>
482</div>
483
484<div class="doc_text">
485
486<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
487bugs in the compiler. In particular, several versions of GCC crash when trying
488to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
489successfully with them (however, see important notes below). Other versions
490of GCC will probably work as well. GCC versions listed
491here are known to not work. If you are using one of these versions, please try
492to upgrade your GCC to something more recent. If you run into a problem with a
493version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
494us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
495of GCC you are using.
496</p>
497
498<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
499problems in the STL that effectively prevent it from compiling LLVM.
500</p>
501
Chris Lattner76bb5302008-02-13 17:50:24 +0000[diff] [blame]502<p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
503a bogus template error. This was fixed in later GCCs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]504
505<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
506href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
507the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
508
509<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]510 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]511 to a newer version</a> if possible.</p>
512<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
513 possibly others) does not compile LLVM correctly (it appears that exception
514 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
515 to a newer version of GCC.</p>
516<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
517 code generator, causing an infinite loop in the llvm-gcc build when built
518 with optimizations enabled (i.e. a release build).</p>
519<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
520 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
521 correctly compiles LLVM at -O2. A work around is to build release LLVM
522 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
523<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
524 miscompiles portions of LLVM</a>.</p>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]525<p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
526 when building with optimizations enabled. It appears to work with
527 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
528 build.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]529<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
530 miscompile LLVM.</p>
531<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
532 default with ENABLE_OPTIMIZED=1. To work around this, build with
533 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
534<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
535 compiling some files. At the time of this writing, GCC mainline (4.2)
536 did not share the problem.</p>
537<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
538 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
539 code. LLVM will appear to mostly work but will be buggy, e.g. failing
540 portions of its testsuite.</p>
541<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
542platforms compiling md5.c gets a mangled constant.</p>
Daniel Dunbar597fdcd2008-10-11 18:40:33 +0000[diff] [blame]543<p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
544to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
545about symbols remaining in the table on destruction.</p>
Nuno Lopesfc375a62008-12-10 16:11:10 +0000[diff] [blame]546<p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
Nuno Lopesc36ac042008-12-10 16:01:22 +0000[diff] [blame]547as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
Anton Korobeynikov30403a02009-05-04 10:24:46 +0000[diff] [blame^]548<p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
549 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
550 with link errors when using this GCC version.</p>
Daniel Dunbar597fdcd2008-10-11 18:40:33 +0000[diff] [blame]551
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]552<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
553long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
554defined in a discarded section. You can safely ignore these messages as they are
555erroneous and the linkage is correct. These messages disappear using ld
5562.17.</p>
557
558<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
559href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
560causes huge link times (minutes instead of seconds) when building LLVM. We
561recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
562
Nick Lewycky87da07c2009-03-03 05:41:16 +0000[diff] [blame]563<p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
Nick Lewycky829108e2009-02-25 06:29:47 +0000[diff] [blame]564<a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
565which causes intermittent failures when building LLVM with position independent
Nick Lewycky87da07c2009-03-03 05:41:16 +0000[diff] [blame]566code. The symptom is an error about cyclic dependencies. We recommend
567upgrading to a newer version of Gold.</p>
Nick Lewycky829108e2009-02-25 06:29:47 +0000[diff] [blame]568
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]569</div>
570
571
572
573<!-- *********************************************************************** -->
574<div class="doc_section">
575 <a name="starting"><b>Getting Started with LLVM</b></a>
576</div>
577<!-- *********************************************************************** -->
578
579<div class="doc_text">
580
581<p>The remainder of this guide is meant to get you up and running with
582LLVM and to give you some basic information about the LLVM environment.</p>
583
584<p>The later sections of this guide describe the <a
585href="#layout">general layout</a> of the the LLVM source tree, a <a
586href="#tutorial">simple example</a> using the LLVM tool chain, and <a
587href="#links">links</a> to find more information about LLVM or to get
588help via e-mail.</p>
589</div>
590
591<!-- ======================================================================= -->
592<div class="doc_subsection">
593 <a name="terminology">Terminology and Notation</a>
594</div>
595
596<div class="doc_text">
597
598<p>Throughout this manual, the following names are used to denote paths
599specific to the local system and working environment. <i>These are not
600environment variables you need to set but just strings used in the rest
601of this document below</i>. In any of the examples below, simply replace
602each of these names with the appropriate pathname on your local system.
603All these paths are absolute:</p>
604
605<dl>
606 <dt>SRC_ROOT
607 <dd>
608 This is the top level directory of the LLVM source tree.
609 <br><br>
610
611 <dt>OBJ_ROOT
612 <dd>
613 This is the top level directory of the LLVM object tree (i.e. the
614 tree where object files and compiled programs will be placed. It
615 can be the same as SRC_ROOT).
616 <br><br>
617
618 <dt>LLVMGCCDIR
619 <dd>
620 This is where the LLVM GCC Front End is installed.
621 <p>
622 For the pre-built GCC front end binaries, the LLVMGCCDIR is
623 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
624</dl>
625
626</div>
627
628<!-- ======================================================================= -->
629<div class="doc_subsection">
630 <a name="environment">Setting Up Your Environment</a>
631</div>
632
633<div class="doc_text">
634
635<p>
636In order to compile and use LLVM, you may need to set some environment
637variables.
638
639<dl>
640 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
641 <dd>[Optional] This environment variable helps LLVM linking tools find the
642 locations of your bitcode libraries. It is provided only as a
643 convenience since you can specify the paths using the -L options of the
644 tools and the C/C++ front-end will automatically use the bitcode files
645 installed in its
646 <tt>lib</tt> directory.</dd>
647</dl>
648
649</div>
650
651<!-- ======================================================================= -->
652<div class="doc_subsection">
653 <a name="unpack">Unpacking the LLVM Archives</a>
654</div>
655
656<div class="doc_text">
657
658<p>
659If you have the LLVM distribution, you will need to unpack it before you
660can begin to compile it. LLVM is distributed as a set of two files: the LLVM
661suite and the LLVM GCC front end compiled for your platform. There is an
662additional test suite that is optional. Each file is a TAR archive that is
663compressed with the gzip program.
664</p>
665
666<p>The files are as follows, with <em>x.y</em> marking the version number:
667<dl>
668 <dt><tt>llvm-x.y.tar.gz</tt></dt>
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]669 <dd>Source release for the LLVM libraries and tools.<br></dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]670
671 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
672 <dd>Source release for the LLVM test suite.</dd>
673
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]674 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
675 <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]676 directory for build instructions.<br></dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]677
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]678 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
679 <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]680
681</dl>
682
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]683</div>
684
685<!-- ======================================================================= -->
686<div class="doc_subsection">
687 <a name="checkout">Checkout LLVM from Subversion</a>
688</div>
689
690<div class="doc_text">
691
692<p>If you have access to our Subversion repository, you can get a fresh copy of
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]693the entire source code. All you need to do is check it out from Subversion as
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]694follows:</p>
695
696<ul>
697 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
698 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
699 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
700 llvm</tt></li>
701</ul>
702
703
704<p>This will create an '<tt>llvm</tt>' directory in the current
705directory and fully populate it with the LLVM source code, Makefiles,
706test directories, and local copies of documentation files.</p>
707
708<p>If you want to get a specific release (as opposed to the most recent
709revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
710'<tt>trunk</tt>'). The following releases are located in the following
Misha Brukman8e73a472008-12-17 16:27:23 +0000[diff] [blame]711subdirectories of the '<tt>tags</tt>' directory:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]712
713<ul>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]714<li>Release 2.5: <b>RELEASE_25</b></li>
Misha Brukman8e73a472008-12-17 16:27:23 +0000[diff] [blame]715<li>Release 2.4: <b>RELEASE_24</b></li>
Tanya Lattner9eb3be52008-06-09 06:02:09 +0000[diff] [blame]716<li>Release 2.3: <b>RELEASE_23</b></li>
Tanya Lattner60030782008-02-12 02:42:55 +0000[diff] [blame]717<li>Release 2.2: <b>RELEASE_22</b></li>
Tanya Lattner2fad5b02007-09-28 22:50:54 +0000[diff] [blame]718<li>Release 2.1: <b>RELEASE_21</b></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]719<li>Release 2.0: <b>RELEASE_20</b></li>
720<li>Release 1.9: <b>RELEASE_19</b></li>
721<li>Release 1.8: <b>RELEASE_18</b></li>
722<li>Release 1.7: <b>RELEASE_17</b></li>
723<li>Release 1.6: <b>RELEASE_16</b></li>
724<li>Release 1.5: <b>RELEASE_15</b></li>
725<li>Release 1.4: <b>RELEASE_14</b></li>
726<li>Release 1.3: <b>RELEASE_13</b></li>
727<li>Release 1.2: <b>RELEASE_12</b></li>
728<li>Release 1.1: <b>RELEASE_11</b></li>
729<li>Release 1.0: <b>RELEASE_1</b></li>
730</ul>
731
732<p>If you would like to get the LLVM test suite (a separate package as of 1.4),
733you get it from the Subversion repository:</p>
734
735<div class="doc_code">
736<pre>
737% cd llvm/projects
738% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
739</pre>
740</div>
741
742<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
743configured by the LLVM configure script as well as automatically updated when
744you run <tt>svn update</tt>.</p>
745
746<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]747and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]748instructions</a> to successfully get and build the LLVM GCC front-end.</p>
749
750</div>
751
752<!-- ======================================================================= -->
753<div class="doc_subsection">
754 <a name="installcf">Install the GCC Front End</a>
755</div>
756
757<div class="doc_text">
758
759<p>Before configuring and compiling the LLVM suite, you can optionally extract the
760LLVM GCC front end from the binary distribution. It is used for running the
761llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]762<a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]763main LLVM repository.</p>
764
765<p>To install the GCC front end, do the following:</p>
766
767<ol>
768 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]769 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]770 -</tt></li>
771</ol>
772
773<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
774llvm-g++ to some directory in your path. When you configure LLVM, it will
775automatically detect llvm-gcc's presence (if it is in your path) enabling its
776use in llvm-test. Note that you can always build or install llvm-gcc at any
777pointer after building the main LLVM repository: just reconfigure llvm and
778llvm-test will pick it up.
779</p>
780
781<p>The binary versions of the GCC front end may not suit all of your needs. For
782example, the binary distribution may include an old version of a system header
783file, not "fix" a header file that needs to be fixed for GCC, or it may be
784linked with libraries not available on your system.</p>
785
786<p>In cases like these, you may want to try <a
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]787href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]788much easier now than it was in the past.</p>
789
790</div>
791
792<!-- ======================================================================= -->
793<div class="doc_subsection">
794 <a name="config">Local LLVM Configuration</a>
795</div>
796
797<div class="doc_text">
798
799 <p>Once checked out from the Subversion repository, the LLVM suite source
800 code must be
801configured via the <tt>configure</tt> script. This script sets variables in the
802various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
803<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
804the Makefiles needed to begin building LLVM.</p>
805
806<p>The following environment variables are used by the <tt>configure</tt>
807script to configure the build system:</p>
808
809<table summary="LLVM configure script environment variables">
810 <tr><th>Variable</th><th>Purpose</th></tr>
811 <tr>
812 <td>CC</td>
813 <td>Tells <tt>configure</tt> which C compiler to use. By default,
814 <tt>configure</tt> will look for the first GCC C compiler in
815 <tt>PATH</tt>. Use this variable to override
816 <tt>configure</tt>'s default behavior.</td>
817 </tr>
818 <tr>
819 <td>CXX</td>
820 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
821 <tt>configure</tt> will look for the first GCC C++ compiler in
822 <tt>PATH</tt>. Use this variable to override
823 <tt>configure</tt>'s default behavior.</td>
824 </tr>
825</table>
826
827<p>The following options can be used to set or enable LLVM specific options:</p>
828
829<dl>
830 <dt><i>--with-llvmgccdir</i></dt>
831 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
832 The value of this option should specify the full pathname of the C/C++ Front
833 End to be used. If this option is not provided, the PATH will be searched for
834 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
835 be inferred from the path found. If the option is not given, and no llvm-gcc
836 can be found in the path then a warning will be produced by
837 <tt>configure</tt> indicating this situation. LLVM may still be built with
838 the <tt>tools-only</tt> target but attempting to build the runtime libraries
839 will fail as these libraries require llvm-gcc and llvm-g++. See
840 <a href="#installcf">Install the GCC Front End</a> for details on installing
841 the C/C++ Front End. See
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]842 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]843 for details on building the C/C++ Front End.</dd>
844 <dt><i>--with-tclinclude</i></dt>
845 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
846 found. Use this if you have multiple tcl installations on your machine and you
847 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
848 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
849 option, the LLVM configure script will search for the tcl 8.4 and 8.3
850 releases.
851 <br><br>
852 </dd>
853 <dt><i>--enable-optimized</i></dt>
854 <dd>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]855 Enables optimized compilation (debugging symbols are removed
856 and GCC optimization flags are enabled). Note that this is the default
857 setting if you are using the LLVM distribution. The default behavior
858 of an Subversion checkout is to use an unoptimized build (also known as a
859 debug build).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]860 <br><br>
861 </dd>
862 <dt><i>--enable-debug-runtime</i></dt>
863 <dd>
864 Enables debug symbols in the runtime libraries. The default is to strip
865 debug symbols from the runtime libraries.
866 </dd>
867 <dt><i>--enable-jit</i></dt>
868 <dd>
869 Compile the Just In Time (JIT) compiler functionality. This is not
870 available
871 on all platforms. The default is dependent on platform, so it is best
872 to explicitly enable it if you want it.
873 <br><br>
874 </dd>
875 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
876 <dd>Controls which targets will be built and linked into llc. The default
877 value for <tt>target_options</tt> is "all" which builds and links all
878 available targets. The value "host-only" can be specified to build only a
879 native compiler (no cross-compiler targets available). The "native" target is
880 selected as the target of the build host. You can also specify a comma
881 separated list of target names that you want available in llc. The target
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]882 names use all lower case. The current set of targets is: <br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]883 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
884 <br><br></dd>
885 <dt><i>--enable-doxygen</i></dt>
886 <dd>Look for the doxygen program and enable construction of doxygen based
887 documentation from the source code. This is disabled by default because
888 generating the documentation can take a long time and producess 100s of
889 megabytes of output.</dd>
890 <dt><i>--with-udis86</i></dt>
891 <dd>LLVM can use external disassembler library for various purposes (now it's
892 used only for examining code produced by JIT). This option will enable usage
893 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
894 bits) disassembler library.</dd>
895</dl>
896
897<p>To configure LLVM, follow these steps:</p>
898
899<ol>
900 <li><p>Change directory into the object root directory:</p>
901
902 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
903
904 <li><p>Run the <tt>configure</tt> script located in the LLVM source
905 tree:</p>
906
907 <div class="doc_code">
908 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
909 </div></li>
910</ol>
911
912</div>
913
914<!-- ======================================================================= -->
915<div class="doc_subsection">
916 <a name="compile">Compiling the LLVM Suite Source Code</a>
917</div>
918
919<div class="doc_text">
920
921<p>Once you have configured LLVM, you can build it. There are three types of
922builds:</p>
923
924<dl>
925 <dt>Debug Builds
926 <dd>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]927 These builds are the default when one is using an Subversion checkout and
928 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
929 used during configuration). The build system will compile the tools and
930 libraries with debugging information. To get a Debug Build using the
931 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
932 to <tt>configure</tt>.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]933 <br><br>
934
935 <dt>Release (Optimized) Builds
936 <dd>
937 These builds are enabled with the <tt>--enable-optimized</tt> option to
938 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
939 <tt>gmake</tt> command line. For these builds, the build system will
940 compile the tools and libraries with GCC optimizations enabled and strip
941 debugging information from the libraries and executables it generates.
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]942 Note that Release Builds are default when using an LLVM distribution.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]943 <br><br>
944
945 <dt>Profile Builds
946 <dd>
947 These builds are for use with profiling. They compile profiling
948 information into the code for use with programs like <tt>gprof</tt>.
949 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
950 on the <tt>gmake</tt> command line.
951</dl>
952
953<p>Once you have LLVM configured, you can build it by entering the
954<i>OBJ_ROOT</i> directory and issuing the following command:</p>
955
956<div class="doc_code"><pre>% gmake</pre></div>
957
958<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
959are using a version of GCC that is known not to compile LLVM.</p>
960
961<p>
962If you have multiple processors in your machine, you may wish to use some of
963the parallel build options provided by GNU Make. For example, you could use the
964command:</p>
965
966<div class="doc_code"><pre>% gmake -j2</pre></div>
967
968<p>There are several special targets which are useful when working with the LLVM
969source code:</p>
970
971<dl>
972 <dt><tt>gmake clean</tt>
973 <dd>
974 Removes all files generated by the build. This includes object files,
975 generated C/C++ files, libraries, and executables.
976 <br><br>
977
978 <dt><tt>gmake dist-clean</tt>
979 <dd>
980 Removes everything that <tt>gmake clean</tt> does, but also removes files
981 generated by <tt>configure</tt>. It attempts to return the source tree to the
982 original state in which it was shipped.
983 <br><br>
984
985 <dt><tt>gmake install</tt>
986 <dd>
987 Installs LLVM header files, libraries, tools, and documentation in a
988 hierarchy
989 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
990 defaults to <tt>/usr/local</tt>.
991 <br><br>
992
993 <dt><tt>gmake -C runtime install-bytecode</tt>
994 <dd>
995 Assuming you built LLVM into $OBJDIR, when this command is run, it will
996 install bitcode libraries into the GCC front end's bitcode library
997 directory. If you need to update your bitcode libraries,
998 this is the target to use once you've built them.
999 <br><br>
1000</dl>
1001
1002<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1003details on these <tt>make</tt> targets and descriptions of other targets
1004available.</p>
1005
1006<p>It is also possible to override default values from <tt>configure</tt> by
1007declaring variables on the command line. The following are some examples:</p>
1008
1009<dl>
1010 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1011 <dd>
1012 Perform a Release (Optimized) build.
1013 <br><br>
1014
1015 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1016 <dd>
1017 Perform a Release (Optimized) build without assertions enabled.
1018 <br><br>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]1019
1020 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1021 <dd>
1022 Perform a Debug build.
1023 <br><br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1024
1025 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1026 <dd>
1027 Perform a Profiling build.
1028 <br><br>
1029
1030 <dt><tt>gmake VERBOSE=1</tt>
1031 <dd>
1032 Print what <tt>gmake</tt> is doing on standard output.
1033 <br><br>
1034
1035 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1036 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1037 the standard output. This also implies <tt>VERBOSE=1</tt>.
1038 <br><br></dd>
1039</dl>
1040
1041<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1042it and any subdirectories that it contains. Entering any directory inside the
1043LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1044that directory that is out of date.</p>
1045
1046</div>
1047
1048<!-- ======================================================================= -->
1049<div class="doc_subsection">
1050 <a name="cross-compile">Cross-Compiling LLVM</a>
1051</div>
1052
1053<div class="doc_text">
Jim Grosbachc8c74362009-04-17 17:25:16 +0000[diff] [blame]1054 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1055 executables and libraries to be hosted on a platform different from the
1056 platform where they are build (a Canadian Cross build). To configure a
1057 cross-compile, supply the configure script with <tt>--build</tt> and
1058 <tt>--host</tt> options that are different. The values of these options must
1059 be legal target triples that your GCC compiler supports.</p>
1060
1061 <p>The result of such a build is executables that are not runnable on
1062 on the build host (--build option) but can be executed on the compile host
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1063 (--host option).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1064</div>
1065
1066<!-- ======================================================================= -->
1067<div class="doc_subsection">
1068 <a name="objfiles">The Location of LLVM Object Files</a>
1069</div>
1070
1071<div class="doc_text">
1072
1073<p>The LLVM build system is capable of sharing a single LLVM source tree among
1074several LLVM builds. Hence, it is possible to build LLVM for several different
1075platforms or configurations using the same source tree.</p>
1076
1077<p>This is accomplished in the typical autoconf manner:</p>
1078
1079<ul>
1080 <li><p>Change directory to where the LLVM object files should live:</p>
1081
1082 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1083
1084 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1085 directory:</p>
1086
1087 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1088</ul>
1089
1090<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1091named after the build type:</p>
1092
1093<dl>
1094 <dt>Debug Builds
1095 <dd>
1096 <dl>
1097 <dt>Tools
1098 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1099 <dt>Libraries
1100 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1101 </dl>
1102 <br><br>
1103
1104 <dt>Release Builds
1105 <dd>
1106 <dl>
1107 <dt>Tools
1108 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1109 <dt>Libraries
1110 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1111 </dl>
1112 <br><br>
1113
1114 <dt>Profile Builds
1115 <dd>
1116 <dl>
1117 <dt>Tools
1118 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1119 <dt>Libraries
1120 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1121 </dl>
1122</dl>
1123
1124</div>
1125
1126<!-- ======================================================================= -->
1127<div class="doc_subsection">
1128 <a name="optionalconfig">Optional Configuration Items</a>
1129</div>
1130
1131<div class="doc_text">
1132
1133<p>
1134If you're running on a Linux system that supports the "<a
1135href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1136module, and you have root access on the system, you can set your system up to
1137execute LLVM bitcode files directly. To do this, use commands like this (the
1138first command may not be required if you are already using the module):</p>
1139
1140<div class="doc_code">
1141<pre>
1142$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1143$ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1144$ chmod u+x hello.bc (if needed)
1145$ ./hello.bc
1146</pre>
1147</div>
1148
1149<p>
1150This allows you to execute LLVM bitcode files directly. Thanks to Jack
1151Cummings for pointing this out!
1152</p>
1153
1154</div>
1155
1156
1157<!-- *********************************************************************** -->
1158<div class="doc_section">
1159 <a name="layout"><b>Program Layout</b></a>
1160</div>
1161<!-- *********************************************************************** -->
1162
1163<div class="doc_text">
1164
1165<p>One useful source of information about the LLVM source base is the LLVM <a
1166href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1167href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1168The following is a brief introduction to code layout:</p>
1169
1170</div>
1171
1172<!-- ======================================================================= -->
1173<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1174<div class="doc_text">
1175 <p>This directory contains some simple examples of how to use the LLVM IR and
1176 JIT.</p>
1177</div>
1178
1179<!-- ======================================================================= -->
1180<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1181<div class="doc_text">
1182
1183<p>This directory contains public header files exported from the LLVM
1184library. The three main subdirectories of this directory are:</p>
1185
1186<dl>
1187 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1188 <dd>This directory contains all of the LLVM specific header files. This
1189 directory also has subdirectories for different portions of LLVM:
1190 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1191 etc...</dd>
1192
1193 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1194 <dd>This directory contains generic support libraries that are provided with
1195 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1196 and a Command Line option processing library store their header files here.
1197 </dd>
1198
1199 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1200 <dd>This directory contains header files configured by the <tt>configure</tt>
1201 script. They wrap "standard" UNIX and C header files. Source code can
1202 include these header files which automatically take care of the conditional
1203 #includes that the <tt>configure</tt> script generates.</dd>
1204</dl>
1205</div>
1206
1207<!-- ======================================================================= -->
1208<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1209<div class="doc_text">
1210
1211<p>This directory contains most of the source files of the LLVM system. In LLVM,
1212almost all code exists in libraries, making it very easy to share code among the
1213different <a href="#tools">tools</a>.</p>
1214
1215<dl>
1216 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1217 <dd> This directory holds the core LLVM source files that implement core
1218 classes like Instruction and BasicBlock.</dd>
1219
1220 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1221 <dd>This directory holds the source code for the LLVM assembly language parser
1222 library.</dd>
1223
1224 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1225 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1226
1227 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1228 different program analyses, such as Dominator Information, Call Graphs,
1229 Induction Variables, Interval Identification, Natural Loop Identification,
1230 etc.</dd>
1231
1232 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1233 <dd> This directory contains the source code for the LLVM to LLVM program
1234 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1235 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1236 Elimination, and many others.</dd>
1237
1238 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1239 <dd> This directory contains files that describe various target architectures
1240 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1241 directory holds the X86 machine description while
1242 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1243
1244 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1245 <dd> This directory contains the major parts of the code generator: Instruction
1246 Selector, Instruction Scheduling, and Register Allocation.</dd>
1247
1248 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1249 <dd> This directory contains the source level debugger library that makes
1250 it possible to instrument LLVM programs so that a debugger could identify
1251 source code locations at which the program is executing.</dd>
1252
1253 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1254 <dd> This directory contains libraries for executing LLVM bitcode directly
1255 at runtime in both interpreted and JIT compiled fashions.</dd>
1256
1257 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1258 <dd> This directory contains the source code that corresponds to the header
1259 files located in <tt>llvm/include/Support/</tt>.</dd>
1260
1261 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1262 <dd>This directory contains the operating system abstraction layer that
1263 shields LLVM from platform-specific coding.</dd>
1264</dl>
1265
1266</div>
1267
1268<!-- ======================================================================= -->
1269<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1270<div class="doc_text">
1271 <p>This directory contains projects that are not strictly part of LLVM but are
1272 shipped with LLVM. This is also the directory where you should create your own
1273 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
Chris Lattneraf1df782008-08-11 06:13:31 +0000[diff] [blame]1274 to set up your own project.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1275</div>
1276
1277<!-- ======================================================================= -->
1278<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1279<div class="doc_text">
1280
1281<p>This directory contains libraries which are compiled into LLVM bitcode and
1282used when linking programs with the GCC front end. Most of these libraries are
1283skeleton versions of real libraries; for example, libc is a stripped down
1284version of glibc.</p>
1285
1286<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1287end to compile.</p>
1288
1289</div>
1290
1291<!-- ======================================================================= -->
1292<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1293<div class="doc_text">
1294 <p>This directory contains feature and regression tests and other basic sanity
1295 checks on the LLVM infrastructure. These are intended to run quickly and cover
1296 a lot of territory without being exhaustive.</p>
1297</div>
1298
1299<!-- ======================================================================= -->
1300<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1301<div class="doc_text">
1302 <p>This is not a directory in the normal llvm module; it is a separate
1303 Subversion
1304 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1305 This
1306 module contains a comprehensive correctness, performance, and benchmarking
1307 test
1308 suite for LLVM. It is a separate Subversion module because not every LLVM
1309 user is
1310 interested in downloading or building such a comprehensive test suite. For
1311 further details on this test suite, please see the
1312 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1313</div>
1314
1315<!-- ======================================================================= -->
1316<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1317<div class="doc_text">
1318
1319<p>The <b>tools</b> directory contains the executables built out of the
1320libraries above, which form the main part of the user interface. You can
1321always get help for a tool by typing <tt>tool_name --help</tt>. The
1322following is a brief introduction to the most important tools. More detailed
1323information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1324
1325<dl>
1326
1327 <dt><tt><b>bugpoint</b></tt></dt>
1328 <dd><tt>bugpoint</tt> is used to debug
1329 optimization passes or code generation backends by narrowing down the
1330 given test case to the minimum number of passes and/or instructions that
1331 still cause a problem, whether it is a crash or miscompilation. See <a
1332 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1333 on using <tt>bugpoint</tt>.</dd>
1334
1335 <dt><tt><b>llvmc</b></tt></dt>
1336 <dd>The LLVM Compiler Driver. This program can
1337 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1338 pre-processing, translation, optimization, assembly, and linking of programs
1339 all from one command line. <tt>llvmc</tt> also takes care of processing the
1340 dependent libraries found in bitcode. This reduces the need to get the
1341 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1342 note that this tool, while functional, is still experimental and not feature
1343 complete.</dd>
1344
1345 <dt><tt><b>llvm-ar</b></tt></dt>
1346 <dd>The archiver produces an archive containing
1347 the given LLVM bitcode files, optionally with an index for faster
1348 lookup.</dd>
1349
1350 <dt><tt><b>llvm-as</b></tt></dt>
1351 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1352 bitcode.</dd>
1353
1354 <dt><tt><b>llvm-dis</b></tt></dt>
1355 <dd>The disassembler transforms the LLVM bitcode to human readable
1356 LLVM assembly.</dd>
1357
1358 <dt><tt><b>llvm-ld</b></tt></dt>
1359 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1360 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1361 optimizations and allows optimization modules to be loaded and run so that
1362 language specific optimizations can be applied at link time.</dd>
1363
1364 <dt><tt><b>llvm-link</b></tt></dt>
1365 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1366 a single program.</dd>
1367
1368 <dt><tt><b>lli</b></tt></dt>
1369 <dd><tt>lli</tt> is the LLVM interpreter, which
Nick Lewycky32dc2a12007-12-03 01:58:01 +0000[diff] [blame]1370 can directly execute LLVM bitcode (although very slowly...). For architectures
1371 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1372 will function as a Just-In-Time compiler (if the functionality was compiled
1373 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1374
1375 <dt><tt><b>llc</b></tt></dt>
1376 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1377 translates LLVM bitcode to a native code assembly file or to C code (with
1378 the -march=c option).</dd>
1379
1380 <dt><tt><b>llvm-gcc</b></tt></dt>
1381 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1382 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1383 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1384 usual machine code output. It works just like any other GCC compiler,
1385 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1386 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1387 separate Subversion module.</dd>
1388
1389 <dt><tt><b>opt</b></tt></dt>
1390 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1391 transformations (which are specified on the command line), and then outputs
1392 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]1393 get a list of the program transformations available in LLVM.<br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1394 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1395 LLVM bitcode file and print out the results. It is primarily useful for
1396 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1397</dl>
1398</div>
1399
1400<!-- ======================================================================= -->
1401<div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1402<div class="doc_text">
1403
1404<p>This directory contains utilities for working with LLVM source code, and some
1405of the utilities are actually required as part of the build process because they
1406are code generators for parts of LLVM infrastructure.</p>
1407
1408<dl>
1409 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1410 that finds differences between code that LLC generates and code that LLI
1411 generates. This is a useful tool if you are debugging one of them,
1412 assuming that the other generates correct output. For the full user
1413 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1414
1415 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1416 syntax-highlighting files which will work with Emacs and XEmacs editors,
1417 providing syntax highlighting support for LLVM assembly files and TableGen
1418 description files. For information on how to use the syntax files, consult
1419 the <tt>README</tt> file in that directory.<br><br>
1420
1421 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1422 and outputs all non-generated source files, which is useful if one wishes
1423 to do a lot of development across directories and does not want to
1424 individually find each file. One way to use it is to run, for example:
1425 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1426 tree.<br><br>
1427
1428 <dt><tt><b>llvmgrep</b></tt></dt>
1429 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1430 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1431 line. This is a very efficient way of searching the source base for a
1432 particular regular expression.</dd>
1433
1434 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1435 files in the current directory and then compiles and links the tool that
1436 is the first argument. For example, assuming you are in the directory
1437 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1438 simply running <tt>makellvm llc</tt> will make a build of the current
1439 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1440 causing a re-linking of LLC.<br><br>
1441
1442 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1443 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1444 cron script to generate nightly status reports of the functionality of
1445 tools, and the results can be seen by following the appropriate link on
1446 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1447
1448 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1449 the tool used to generate register descriptions, instruction set
1450 descriptions, and even assemblers from common TableGen description
1451 files.<br><br>
1452
1453 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1454 syntax-highlighting files which will work with the VIM editor, providing
1455 syntax highlighting support for LLVM assembly files and TableGen
1456 description files. For information on how to use the syntax files, consult
1457 the <tt>README</tt> file in that directory.<br><br>
1458
1459</dl>
1460
1461</div>
1462
1463<!-- ======================================================================= -->
1464<div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1465<div class="doc_text">
1466 <p>This directory contains build scripts and project files for use with
1467 Visual C++. This allows developers on Windows to build LLVM without the need
1468 for Cygwin. The contents of this directory should be considered experimental
1469 at this time.
1470 </p>
1471</div>
1472<!-- *********************************************************************** -->
1473<div class="doc_section">
1474 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1475</div>
1476<!-- *********************************************************************** -->
1477
1478<div class="doc_text">
1479<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
Chris Lattnere6099642009-04-10 15:38:51 +0000[diff] [blame]1480so we only include instructions for llvm-gcc4.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1481</p>
1482
1483<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1484from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1485create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1486the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1487<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1488output.</p>
1489</div>
1490
1491<!-- ======================================================================= -->
1492<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1493
1494<div class="doc_text">
1495
1496<ol>
1497 <li><p>First, create a simple C file, name it 'hello.c':</p>
1498
1499<div class="doc_code">
1500<pre>
1501#include &lt;stdio.h&gt;
1502
1503int main() {
1504 printf("hello world\n");
1505 return 0;
1506}
1507</pre></div></li>
1508
1509 <li><p>Next, compile the C file into a native executable:</p>
1510
1511 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1512
1513 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1514 -c arguments work as usual (producing a native .s or .o file,
1515 respectively).</p></li>
1516
1517 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1518
1519 <div class="doc_code">
1520 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1521
1522 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1523 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1524 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1525 the bitcode file.</p>
1526
1527 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1528 </p></li>
1529
1530 <li><p>Run the program in both forms. To run the program, use:</p>
1531
1532 <div class="doc_code"><pre>% ./hello</pre></div>
1533
1534 <p>and</p>
1535
1536 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1537
1538 <p>The second examples shows how to invoke the LLVM JIT, <a
1539 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1540
1541 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1542 code:</p>
1543
1544<div class="doc_code">
1545<pre>llvm-dis &lt; hello.bc | less</pre>
1546</div></li>
1547
1548 <li><p>Compile the program to native assembly using the LLC code
1549 generator:</p>
1550
1551 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1552
1553 <li><p>Assemble the native assembly language file into a program:</p>
1554
1555<div class="doc_code">
1556<pre>
1557<b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1558
1559<b>Others:</b> % gcc hello.s -o hello.native
1560</pre>
1561</div></li>
1562
1563 <li><p>Execute the native code program:</p>
1564
1565 <div class="doc_code"><pre>% ./hello.native</pre></div>
1566
1567 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1568 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1569 </li>
1570
1571</ol>
1572
1573</div>
1574
1575
1576<!-- *********************************************************************** -->
1577<div class="doc_section">
1578 <a name="problems">Common Problems</a>
1579</div>
1580<!-- *********************************************************************** -->
1581
1582<div class="doc_text">
1583
1584<p>If you are having problems building or using LLVM, or if you have any other
1585general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1586Asked Questions</a> page.</p>
1587
1588</div>
1589
1590<!-- *********************************************************************** -->
1591<div class="doc_section">
1592 <a name="links">Links</a>
1593</div>
1594<!-- *********************************************************************** -->
1595
1596<div class="doc_text">
1597
Bill Wendling08f49b92008-07-22 01:10:25 +0000[diff] [blame]1598<p>This document is just an <b>introduction</b> on how to use LLVM to do
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1599some simple things... there are many more interesting and complicated things
1600that you can do that aren't documented here (but we'll gladly accept a patch
1601if you want to write something up!). For more information about LLVM, check
1602out:</p>
1603
1604<ul>
1605 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1606 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1607 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1608 that Uses LLVM</a></li>
1609</ul>
1610
1611</div>
1612
1613<!-- *********************************************************************** -->
1614
1615<hr>
1616<address>
1617 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1618 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1619 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]1620 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1621
1622 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1623 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1624 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1625 Last modified: $Date$
1626</address>
1627</body>
1628</html>