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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>
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>
Chris Lattner6abf6762009-07-22 04:21:40 +0000[diff] [blame]219 <td>AuroraUX</td>
220 <td>x86<sup><a href="#pf_1">1</a></sup></td>
221 <td>GCC</td>
Chris Lattnera8f23072009-07-21 22:47:03 +0000[diff] [blame]222</tr>
223<tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]224 <td>Linux</td>
225 <td>x86<sup><a href="#pf_1">1</a></sup></td>
226 <td>GCC</td>
227</tr>
228<tr>
Edward O'Callaghan82a57db2009-08-04 05:24:28 +0000[diff] [blame^]229 <td>Linux</td>
230 <td>amd64</td>
231 <td>GCC</td>
232</tr>
233<tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]234 <td>Solaris</td>
235 <td>V9 (Ultrasparc)</td>
236 <td>GCC</td>
237</tr>
238<tr>
239 <td>FreeBSD</td>
240 <td>x86<sup><a href="#pf_1">1</a></sup></td>
241 <td>GCC</td>
242</tr>
243<tr>
244 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
245 <td>PowerPC</td>
246 <td>GCC</td>
247</tr>
248<tr>
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]249 <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]250 <td>x86</td>
251 <td>GCC</td>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]252</tr>
253<tr>
254 <td>Cygwin/Win32</td>
255 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
256 <td>GCC 3.4.X, binutils 2.15</td>
257</tr>
258<tr>
259 <td>MinGW/Win32</td>
260 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
261 <td>GCC 3.4.X, binutils 2.15</td>
262</tr>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]263</table>
264
265<p>LLVM has partial support for the following platforms:</p>
266
267<table summary="LLVM partial platform support">
268<tr>
269 <th>OS</th>
270 <th>Arch</th>
271 <th>Compilers</th>
272</tr>
273<tr>
274 <td>Windows</td>
275 <td>x86<sup><a href="#pf_1">1</a></sup></td>
Nick Lewycky18b90af2008-12-08 00:45:02 +0000[diff] [blame]276 <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]277<tr>
278 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
279 <td>PowerPC</td>
280 <td>GCC</td>
281</tr>
282<tr>
283 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
284 <td>PowerPC</td>
285 <td>GCC</td>
286</tr>
287
288<tr>
289 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
290 <td>Alpha</td>
291 <td>GCC</td>
292</tr>
293<tr>
294 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
295 <td>Itanium (IA-64)</td>
296 <td>GCC</td>
297</tr>
298<tr>
299 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
300 <td>Itanium (IA-64)</td>
301 <td>HP aCC</td>
302</tr>
303</table>
304
305<p><b>Notes:</b></p>
306
307<div class="doc_notes">
308<ol>
309<li><a name="pf_1">Code generation supported for Pentium processors and
310up</a></li>
311<li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
312<li><a name="pf_3">No native code generation</a></li>
Nick Lewycky18b90af2008-12-08 00:45:02 +0000[diff] [blame]313<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]314<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]315<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]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>
Chris Lattnerfdae8682008-11-09 17:19:14 +0000[diff] [blame]323<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]324 internal LLVM assert messages when compiled for Release at optimization
Chris Lattnerfdae8682008-11-09 17:19:14 +0000[diff] [blame]325 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
326 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
Scott Michel6de83ff2008-03-18 23:13:26 +0000[diff] [blame]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
Chris Lattner15aeb9a2009-04-25 22:08:52 +0000[diff] [blame]334tools). If you do not need many of the tools and you are space-conscious, you
335can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
336requires considerably less space.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]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>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]380 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
381 <td>&ge;1.3</td>
382 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
383 </tr>
384
385 <tr>
386 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
387 <td>1.4.2</td>
388 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
389 </tr>
390
391 <tr>
392 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
393 <td>8.3, 8.4</td>
394 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
395 </tr>
396
397 <tr>
398 <td><a href="http://expect.nist.gov/">expect</a></td>
399 <td>5.38.0</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.perl.com/download.csp">perl</a></td>
405 <td>&ge;5.6.0</td>
406 <td>Nightly tester, utilities</td>
407 </tr>
408
409 <tr>
410 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
411 <td>1.4</td>
412 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
413 </tr>
414
415 <tr>
416 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
417 <td>2.59</td>
418 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
419 </tr>
420
421 <tr>
422 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
423 <td>1.9.2</td>
424 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
425 </tr>
426
427 <tr>
428 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
429 <td>1.5.10</td>
430 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
431 </tr>
432
433 </table>
434
435 <p><b>Notes:</b></p>
436 <div class="doc_notes">
437 <ol>
438 <li><a name="sf1">Only the C and C++ languages are needed so there's no
439 need to build the other languages for LLVM's purposes.</a> See
440 <a href="#brokengcc">below</a> for specific version info.</li>
441 <li><a name="sf2">You only need Subversion if you intend to build from the
442 latest LLVM sources. If you're working from a release distribution, you
443 don't need Subversion.</a></li>
444 <li><a name="sf3">Only needed if you want to run the automated test
445 suite in the <tt>llvm/test</tt> directory.</a></li>
446 <li><a name="sf4">If you want to make changes to the configure scripts,
447 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
448 or higher). You will also need automake (1.9.2). We only use aclocal
449 from that package.</a></li>
450 </ol>
451 </div>
452
453 <p>Additionally, your compilation host is expected to have the usual
454 plethora of Unix utilities. Specifically:</p>
455 <ul>
456 <li><b>ar</b> - archive library builder</li>
457 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
458 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
459 <li><b>chmod</b> - change permissions on a file</li>
460 <li><b>cat</b> - output concatenation utility</li>
461 <li><b>cp</b> - copy files</li>
462 <li><b>date</b> - print the current date/time </li>
463 <li><b>echo</b> - print to standard output</li>
464 <li><b>egrep</b> - extended regular expression search utility</li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]465 <li><b>find</b> - find files/dirs in a file system</li>
466 <li><b>grep</b> - regular expression search utility</li>
467 <li><b>gzip*</b> - gzip command for distribution generation</li>
468 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
469 <li><b>install</b> - install directories/files </li>
470 <li><b>mkdir</b> - create a directory</li>
471 <li><b>mv</b> - move (rename) files</li>
472 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
473 <li><b>rm</b> - remove (delete) files and directories</li>
474 <li><b>sed</b> - stream editor for transforming output</li>
475 <li><b>sh</b> - Bourne shell for make build scripts</li>
476 <li><b>tar</b> - tape archive for distribution generation</li>
477 <li><b>test</b> - test things in file system</li>
478 <li><b>unzip*</b> - unzip command for distribution checking</li>
479 <li><b>zip*</b> - zip command for distribution generation</li>
480 </ul>
481</div>
482
483<!-- ======================================================================= -->
484<div class="doc_subsection">
485 <a name="brokengcc">Broken versions of GCC and other tools</a>
486</div>
487
488<div class="doc_text">
489
490<p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
491bugs in the compiler. In particular, several versions of GCC crash when trying
492to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
493successfully with them (however, see important notes below). Other versions
494of GCC will probably work as well. GCC versions listed
495here are known to not work. If you are using one of these versions, please try
496to upgrade your GCC to something more recent. If you run into a problem with a
497version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
498us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
499of GCC you are using.
500</p>
501
502<p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
503problems in the STL that effectively prevent it from compiling LLVM.
504</p>
505
Chris Lattner76bb5302008-02-13 17:50:24 +0000[diff] [blame]506<p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
507a bogus template error. This was fixed in later GCCs.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]508
509<p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
510href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
511the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
512
513<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]514 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]515 to a newer version</a> if possible.</p>
516<p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
517 possibly others) does not compile LLVM correctly (it appears that exception
518 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
519 to a newer version of GCC.</p>
520<p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
521 code generator, causing an infinite loop in the llvm-gcc build when built
522 with optimizations enabled (i.e. a release build).</p>
523<p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
524 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
525 correctly compiles LLVM at -O2. A work around is to build release LLVM
526 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
527<p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
528 miscompiles portions of LLVM</a>.</p>
Chris Lattner05300e42007-11-01 04:20:16 +0000[diff] [blame]529<p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
530 when building with optimizations enabled. It appears to work with
531 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
532 build.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]533<p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
534 miscompile LLVM.</p>
535<p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
536 default with ENABLE_OPTIMIZED=1. To work around this, build with
537 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
538<p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
539 compiling some files. At the time of this writing, GCC mainline (4.2)
540 did not share the problem.</p>
541<p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
542 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
543 code. LLVM will appear to mostly work but will be buggy, e.g. failing
544 portions of its testsuite.</p>
545<p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
546platforms compiling md5.c gets a mangled constant.</p>
Daniel Dunbar597fdcd2008-10-11 18:40:33 +0000[diff] [blame]547<p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
548to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
549about symbols remaining in the table on destruction.</p>
Nuno Lopesfc375a62008-12-10 16:11:10 +0000[diff] [blame]550<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]551as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
Anton Korobeynikov30403a02009-05-04 10:24:46 +0000[diff] [blame]552<p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
553 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
554 with link errors when using this GCC version.</p>
Nick Lewyckyadb7b152009-07-17 06:32:10 +0000[diff] [blame]555<p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
556when optimizations are turned on. The symptom is an infinite loop in
557FoldingSetImpl::RemoveNode while running the code generator.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]558<p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
559long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
560defined in a discarded section. You can safely ignore these messages as they are
561erroneous and the linkage is correct. These messages disappear using ld
5622.17.</p>
563
564<p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
565href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
566causes huge link times (minutes instead of seconds) when building LLVM. We
567recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
568
Nick Lewycky87da07c2009-03-03 05:41:16 +0000[diff] [blame]569<p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
Nick Lewycky829108e2009-02-25 06:29:47 +0000[diff] [blame]570<a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
571which causes intermittent failures when building LLVM with position independent
Nick Lewycky87da07c2009-03-03 05:41:16 +0000[diff] [blame]572code. The symptom is an error about cyclic dependencies. We recommend
573upgrading to a newer version of Gold.</p>
Nick Lewycky829108e2009-02-25 06:29:47 +0000[diff] [blame]574
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]575</div>
576
577
578
579<!-- *********************************************************************** -->
580<div class="doc_section">
581 <a name="starting"><b>Getting Started with LLVM</b></a>
582</div>
583<!-- *********************************************************************** -->
584
585<div class="doc_text">
586
587<p>The remainder of this guide is meant to get you up and running with
588LLVM and to give you some basic information about the LLVM environment.</p>
589
590<p>The later sections of this guide describe the <a
591href="#layout">general layout</a> of the the LLVM source tree, a <a
592href="#tutorial">simple example</a> using the LLVM tool chain, and <a
593href="#links">links</a> to find more information about LLVM or to get
594help via e-mail.</p>
595</div>
596
597<!-- ======================================================================= -->
598<div class="doc_subsection">
599 <a name="terminology">Terminology and Notation</a>
600</div>
601
602<div class="doc_text">
603
604<p>Throughout this manual, the following names are used to denote paths
605specific to the local system and working environment. <i>These are not
606environment variables you need to set but just strings used in the rest
607of this document below</i>. In any of the examples below, simply replace
608each of these names with the appropriate pathname on your local system.
609All these paths are absolute:</p>
610
611<dl>
612 <dt>SRC_ROOT
613 <dd>
614 This is the top level directory of the LLVM source tree.
615 <br><br>
616
617 <dt>OBJ_ROOT
618 <dd>
619 This is the top level directory of the LLVM object tree (i.e. the
620 tree where object files and compiled programs will be placed. It
621 can be the same as SRC_ROOT).
622 <br><br>
623
624 <dt>LLVMGCCDIR
625 <dd>
626 This is where the LLVM GCC Front End is installed.
627 <p>
628 For the pre-built GCC front end binaries, the LLVMGCCDIR is
629 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
630</dl>
631
632</div>
633
634<!-- ======================================================================= -->
635<div class="doc_subsection">
636 <a name="environment">Setting Up Your Environment</a>
637</div>
638
639<div class="doc_text">
640
641<p>
642In order to compile and use LLVM, you may need to set some environment
643variables.
644
645<dl>
646 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
647 <dd>[Optional] This environment variable helps LLVM linking tools find the
648 locations of your bitcode libraries. It is provided only as a
649 convenience since you can specify the paths using the -L options of the
650 tools and the C/C++ front-end will automatically use the bitcode files
651 installed in its
652 <tt>lib</tt> directory.</dd>
653</dl>
654
655</div>
656
657<!-- ======================================================================= -->
658<div class="doc_subsection">
659 <a name="unpack">Unpacking the LLVM Archives</a>
660</div>
661
662<div class="doc_text">
663
664<p>
665If you have the LLVM distribution, you will need to unpack it before you
666can begin to compile it. LLVM is distributed as a set of two files: the LLVM
667suite and the LLVM GCC front end compiled for your platform. There is an
668additional test suite that is optional. Each file is a TAR archive that is
669compressed with the gzip program.
670</p>
671
672<p>The files are as follows, with <em>x.y</em> marking the version number:
673<dl>
674 <dt><tt>llvm-x.y.tar.gz</tt></dt>
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]675 <dd>Source release for the LLVM libraries and tools.<br></dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]676
677 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
678 <dd>Source release for the LLVM test suite.</dd>
679
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]680 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
681 <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]682 directory for build instructions.<br></dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]683
Misha Brukman313db032008-12-29 19:38:58 +0000[diff] [blame]684 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
685 <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]686
687</dl>
688
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]689</div>
690
691<!-- ======================================================================= -->
692<div class="doc_subsection">
693 <a name="checkout">Checkout LLVM from Subversion</a>
694</div>
695
696<div class="doc_text">
697
698<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]699the 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]700follows:</p>
701
702<ul>
703 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
704 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
705 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
706 llvm</tt></li>
707</ul>
708
709
710<p>This will create an '<tt>llvm</tt>' directory in the current
711directory and fully populate it with the LLVM source code, Makefiles,
712test directories, and local copies of documentation files.</p>
713
714<p>If you want to get a specific release (as opposed to the most recent
715revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
716'<tt>trunk</tt>'). The following releases are located in the following
Misha Brukman8e73a472008-12-17 16:27:23 +0000[diff] [blame]717subdirectories of the '<tt>tags</tt>' directory:</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]718
719<ul>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]720<li>Release 2.5: <b>RELEASE_25</b></li>
Misha Brukman8e73a472008-12-17 16:27:23 +0000[diff] [blame]721<li>Release 2.4: <b>RELEASE_24</b></li>
Tanya Lattner9eb3be52008-06-09 06:02:09 +0000[diff] [blame]722<li>Release 2.3: <b>RELEASE_23</b></li>
Tanya Lattner60030782008-02-12 02:42:55 +0000[diff] [blame]723<li>Release 2.2: <b>RELEASE_22</b></li>
Tanya Lattner2fad5b02007-09-28 22:50:54 +0000[diff] [blame]724<li>Release 2.1: <b>RELEASE_21</b></li>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]725<li>Release 2.0: <b>RELEASE_20</b></li>
726<li>Release 1.9: <b>RELEASE_19</b></li>
727<li>Release 1.8: <b>RELEASE_18</b></li>
728<li>Release 1.7: <b>RELEASE_17</b></li>
729<li>Release 1.6: <b>RELEASE_16</b></li>
730<li>Release 1.5: <b>RELEASE_15</b></li>
731<li>Release 1.4: <b>RELEASE_14</b></li>
732<li>Release 1.3: <b>RELEASE_13</b></li>
733<li>Release 1.2: <b>RELEASE_12</b></li>
734<li>Release 1.1: <b>RELEASE_11</b></li>
735<li>Release 1.0: <b>RELEASE_1</b></li>
736</ul>
737
738<p>If you would like to get the LLVM test suite (a separate package as of 1.4),
739you get it from the Subversion repository:</p>
740
741<div class="doc_code">
742<pre>
743% cd llvm/projects
744% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
745</pre>
746</div>
747
748<p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
749configured by the LLVM configure script as well as automatically updated when
750you run <tt>svn update</tt>.</p>
751
752<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]753and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]754instructions</a> to successfully get and build the LLVM GCC front-end.</p>
755
756</div>
757
758<!-- ======================================================================= -->
759<div class="doc_subsection">
760 <a name="installcf">Install the GCC Front End</a>
761</div>
762
763<div class="doc_text">
764
765<p>Before configuring and compiling the LLVM suite, you can optionally extract the
766LLVM GCC front end from the binary distribution. It is used for running the
767llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]768<a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]769main LLVM repository.</p>
770
771<p>To install the GCC front end, do the following:</p>
772
773<ol>
774 <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]775 <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]776 -</tt></li>
777</ol>
778
779<p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
780llvm-g++ to some directory in your path. When you configure LLVM, it will
781automatically detect llvm-gcc's presence (if it is in your path) enabling its
782use in llvm-test. Note that you can always build or install llvm-gcc at any
783pointer after building the main LLVM repository: just reconfigure llvm and
784llvm-test will pick it up.
785</p>
786
787<p>The binary versions of the GCC front end may not suit all of your needs. For
788example, the binary distribution may include an old version of a system header
789file, not "fix" a header file that needs to be fixed for GCC, or it may be
790linked with libraries not available on your system.</p>
791
792<p>In cases like these, you may want to try <a
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]793href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]794much easier now than it was in the past.</p>
795
796</div>
797
798<!-- ======================================================================= -->
799<div class="doc_subsection">
800 <a name="config">Local LLVM Configuration</a>
801</div>
802
803<div class="doc_text">
804
805 <p>Once checked out from the Subversion repository, the LLVM suite source
806 code must be
807configured via the <tt>configure</tt> script. This script sets variables in the
808various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
809<tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
810the Makefiles needed to begin building LLVM.</p>
811
812<p>The following environment variables are used by the <tt>configure</tt>
813script to configure the build system:</p>
814
815<table summary="LLVM configure script environment variables">
816 <tr><th>Variable</th><th>Purpose</th></tr>
817 <tr>
818 <td>CC</td>
819 <td>Tells <tt>configure</tt> which C compiler to use. By default,
820 <tt>configure</tt> will look for the first GCC C compiler in
821 <tt>PATH</tt>. Use this variable to override
822 <tt>configure</tt>'s default behavior.</td>
823 </tr>
824 <tr>
825 <td>CXX</td>
826 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
827 <tt>configure</tt> will look for the first GCC C++ compiler in
828 <tt>PATH</tt>. Use this variable to override
829 <tt>configure</tt>'s default behavior.</td>
830 </tr>
831</table>
832
833<p>The following options can be used to set or enable LLVM specific options:</p>
834
835<dl>
836 <dt><i>--with-llvmgccdir</i></dt>
837 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
838 The value of this option should specify the full pathname of the C/C++ Front
839 End to be used. If this option is not provided, the PATH will be searched for
840 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
841 be inferred from the path found. If the option is not given, and no llvm-gcc
842 can be found in the path then a warning will be produced by
843 <tt>configure</tt> indicating this situation. LLVM may still be built with
844 the <tt>tools-only</tt> target but attempting to build the runtime libraries
845 will fail as these libraries require llvm-gcc and llvm-g++. See
846 <a href="#installcf">Install the GCC Front End</a> for details on installing
847 the C/C++ Front End. See
Duncan Sandse38f3dc2008-02-14 17:53:22 +0000[diff] [blame]848 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]849 for details on building the C/C++ Front End.</dd>
850 <dt><i>--with-tclinclude</i></dt>
851 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
852 found. Use this if you have multiple tcl installations on your machine and you
853 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
854 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
855 option, the LLVM configure script will search for the tcl 8.4 and 8.3
856 releases.
857 <br><br>
858 </dd>
859 <dt><i>--enable-optimized</i></dt>
860 <dd>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]861 Enables optimized compilation (debugging symbols are removed
862 and GCC optimization flags are enabled). Note that this is the default
863 setting if you are using the LLVM distribution. The default behavior
864 of an Subversion checkout is to use an unoptimized build (also known as a
865 debug build).
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]866 <br><br>
867 </dd>
868 <dt><i>--enable-debug-runtime</i></dt>
869 <dd>
870 Enables debug symbols in the runtime libraries. The default is to strip
871 debug symbols from the runtime libraries.
872 </dd>
873 <dt><i>--enable-jit</i></dt>
874 <dd>
875 Compile the Just In Time (JIT) compiler functionality. This is not
876 available
877 on all platforms. The default is dependent on platform, so it is best
878 to explicitly enable it if you want it.
879 <br><br>
880 </dd>
881 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
882 <dd>Controls which targets will be built and linked into llc. The default
883 value for <tt>target_options</tt> is "all" which builds and links all
884 available targets. The value "host-only" can be specified to build only a
885 native compiler (no cross-compiler targets available). The "native" target is
886 selected as the target of the build host. You can also specify a comma
887 separated list of target names that you want available in llc. The target
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]888 names use all lower case. The current set of targets is: <br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]889 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
890 <br><br></dd>
891 <dt><i>--enable-doxygen</i></dt>
892 <dd>Look for the doxygen program and enable construction of doxygen based
893 documentation from the source code. This is disabled by default because
894 generating the documentation can take a long time and producess 100s of
895 megabytes of output.</dd>
896 <dt><i>--with-udis86</i></dt>
897 <dd>LLVM can use external disassembler library for various purposes (now it's
898 used only for examining code produced by JIT). This option will enable usage
899 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
900 bits) disassembler library.</dd>
901</dl>
902
903<p>To configure LLVM, follow these steps:</p>
904
905<ol>
906 <li><p>Change directory into the object root directory:</p>
907
908 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
909
910 <li><p>Run the <tt>configure</tt> script located in the LLVM source
911 tree:</p>
912
913 <div class="doc_code">
914 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
915 </div></li>
916</ol>
917
918</div>
919
920<!-- ======================================================================= -->
921<div class="doc_subsection">
922 <a name="compile">Compiling the LLVM Suite Source Code</a>
923</div>
924
925<div class="doc_text">
926
927<p>Once you have configured LLVM, you can build it. There are three types of
928builds:</p>
929
930<dl>
931 <dt>Debug Builds
932 <dd>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]933 These builds are the default when one is using an Subversion checkout and
934 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
935 used during configuration). The build system will compile the tools and
936 libraries with debugging information. To get a Debug Build using the
937 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
938 to <tt>configure</tt>.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]939 <br><br>
940
941 <dt>Release (Optimized) Builds
942 <dd>
943 These builds are enabled with the <tt>--enable-optimized</tt> option to
944 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
945 <tt>gmake</tt> command line. For these builds, the build system will
946 compile the tools and libraries with GCC optimizations enabled and strip
947 debugging information from the libraries and executables it generates.
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]948 Note that Release Builds are default when using an LLVM distribution.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]949 <br><br>
950
951 <dt>Profile Builds
952 <dd>
953 These builds are for use with profiling. They compile profiling
954 information into the code for use with programs like <tt>gprof</tt>.
955 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
956 on the <tt>gmake</tt> command line.
957</dl>
958
959<p>Once you have LLVM configured, you can build it by entering the
960<i>OBJ_ROOT</i> directory and issuing the following command:</p>
961
962<div class="doc_code"><pre>% gmake</pre></div>
963
964<p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
965are using a version of GCC that is known not to compile LLVM.</p>
966
967<p>
968If you have multiple processors in your machine, you may wish to use some of
969the parallel build options provided by GNU Make. For example, you could use the
970command:</p>
971
972<div class="doc_code"><pre>% gmake -j2</pre></div>
973
974<p>There are several special targets which are useful when working with the LLVM
975source code:</p>
976
977<dl>
978 <dt><tt>gmake clean</tt>
979 <dd>
980 Removes all files generated by the build. This includes object files,
981 generated C/C++ files, libraries, and executables.
982 <br><br>
983
984 <dt><tt>gmake dist-clean</tt>
985 <dd>
986 Removes everything that <tt>gmake clean</tt> does, but also removes files
987 generated by <tt>configure</tt>. It attempts to return the source tree to the
988 original state in which it was shipped.
989 <br><br>
990
991 <dt><tt>gmake install</tt>
992 <dd>
993 Installs LLVM header files, libraries, tools, and documentation in a
994 hierarchy
995 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
996 defaults to <tt>/usr/local</tt>.
997 <br><br>
998
999 <dt><tt>gmake -C runtime install-bytecode</tt>
1000 <dd>
1001 Assuming you built LLVM into $OBJDIR, when this command is run, it will
1002 install bitcode libraries into the GCC front end's bitcode library
1003 directory. If you need to update your bitcode libraries,
1004 this is the target to use once you've built them.
1005 <br><br>
1006</dl>
1007
1008<p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1009details on these <tt>make</tt> targets and descriptions of other targets
1010available.</p>
1011
1012<p>It is also possible to override default values from <tt>configure</tt> by
1013declaring variables on the command line. The following are some examples:</p>
1014
1015<dl>
1016 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1017 <dd>
1018 Perform a Release (Optimized) build.
1019 <br><br>
1020
1021 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1022 <dd>
1023 Perform a Release (Optimized) build without assertions enabled.
1024 <br><br>
Chris Lattner3d55fb92009-04-25 22:24:49 +0000[diff] [blame]1025
1026 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1027 <dd>
1028 Perform a Debug build.
1029 <br><br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1030
1031 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1032 <dd>
1033 Perform a Profiling build.
1034 <br><br>
1035
1036 <dt><tt>gmake VERBOSE=1</tt>
1037 <dd>
1038 Print what <tt>gmake</tt> is doing on standard output.
1039 <br><br>
1040
1041 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1042 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1043 the standard output. This also implies <tt>VERBOSE=1</tt>.
1044 <br><br></dd>
1045</dl>
1046
1047<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1048it and any subdirectories that it contains. Entering any directory inside the
1049LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1050that directory that is out of date.</p>
1051
1052</div>
1053
1054<!-- ======================================================================= -->
1055<div class="doc_subsection">
1056 <a name="cross-compile">Cross-Compiling LLVM</a>
1057</div>
1058
1059<div class="doc_text">
Jim Grosbachc8c74362009-04-17 17:25:16 +0000[diff] [blame]1060 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1061 executables and libraries to be hosted on a platform different from the
1062 platform where they are build (a Canadian Cross build). To configure a
1063 cross-compile, supply the configure script with <tt>--build</tt> and
1064 <tt>--host</tt> options that are different. The values of these options must
1065 be legal target triples that your GCC compiler supports.</p>
1066
1067 <p>The result of such a build is executables that are not runnable on
1068 on the build host (--build option) but can be executed on the compile host
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1069 (--host option).</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1070</div>
1071
1072<!-- ======================================================================= -->
1073<div class="doc_subsection">
1074 <a name="objfiles">The Location of LLVM Object Files</a>
1075</div>
1076
1077<div class="doc_text">
1078
1079<p>The LLVM build system is capable of sharing a single LLVM source tree among
1080several LLVM builds. Hence, it is possible to build LLVM for several different
1081platforms or configurations using the same source tree.</p>
1082
1083<p>This is accomplished in the typical autoconf manner:</p>
1084
1085<ul>
1086 <li><p>Change directory to where the LLVM object files should live:</p>
1087
1088 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1089
1090 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1091 directory:</p>
1092
1093 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1094</ul>
1095
1096<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1097named after the build type:</p>
1098
1099<dl>
1100 <dt>Debug Builds
1101 <dd>
1102 <dl>
1103 <dt>Tools
1104 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1105 <dt>Libraries
1106 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1107 </dl>
1108 <br><br>
1109
1110 <dt>Release Builds
1111 <dd>
1112 <dl>
1113 <dt>Tools
1114 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1115 <dt>Libraries
1116 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1117 </dl>
1118 <br><br>
1119
1120 <dt>Profile Builds
1121 <dd>
1122 <dl>
1123 <dt>Tools
1124 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1125 <dt>Libraries
1126 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1127 </dl>
1128</dl>
1129
1130</div>
1131
1132<!-- ======================================================================= -->
1133<div class="doc_subsection">
1134 <a name="optionalconfig">Optional Configuration Items</a>
1135</div>
1136
1137<div class="doc_text">
1138
1139<p>
1140If you're running on a Linux system that supports the "<a
1141href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1142module, and you have root access on the system, you can set your system up to
1143execute LLVM bitcode files directly. To do this, use commands like this (the
1144first command may not be required if you are already using the module):</p>
1145
1146<div class="doc_code">
1147<pre>
1148$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1149$ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1150$ chmod u+x hello.bc (if needed)
1151$ ./hello.bc
1152</pre>
1153</div>
1154
1155<p>
1156This allows you to execute LLVM bitcode files directly. Thanks to Jack
1157Cummings for pointing this out!
1158</p>
1159
1160</div>
1161
1162
1163<!-- *********************************************************************** -->
1164<div class="doc_section">
1165 <a name="layout"><b>Program Layout</b></a>
1166</div>
1167<!-- *********************************************************************** -->
1168
1169<div class="doc_text">
1170
1171<p>One useful source of information about the LLVM source base is the LLVM <a
1172href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1173href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1174The following is a brief introduction to code layout:</p>
1175
1176</div>
1177
1178<!-- ======================================================================= -->
1179<div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1180<div class="doc_text">
1181 <p>This directory contains some simple examples of how to use the LLVM IR and
1182 JIT.</p>
1183</div>
1184
1185<!-- ======================================================================= -->
1186<div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1187<div class="doc_text">
1188
1189<p>This directory contains public header files exported from the LLVM
1190library. The three main subdirectories of this directory are:</p>
1191
1192<dl>
1193 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1194 <dd>This directory contains all of the LLVM specific header files. This
1195 directory also has subdirectories for different portions of LLVM:
1196 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1197 etc...</dd>
1198
1199 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1200 <dd>This directory contains generic support libraries that are provided with
1201 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1202 and a Command Line option processing library store their header files here.
1203 </dd>
1204
1205 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1206 <dd>This directory contains header files configured by the <tt>configure</tt>
1207 script. They wrap "standard" UNIX and C header files. Source code can
1208 include these header files which automatically take care of the conditional
1209 #includes that the <tt>configure</tt> script generates.</dd>
1210</dl>
1211</div>
1212
1213<!-- ======================================================================= -->
1214<div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1215<div class="doc_text">
1216
1217<p>This directory contains most of the source files of the LLVM system. In LLVM,
1218almost all code exists in libraries, making it very easy to share code among the
1219different <a href="#tools">tools</a>.</p>
1220
1221<dl>
1222 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1223 <dd> This directory holds the core LLVM source files that implement core
1224 classes like Instruction and BasicBlock.</dd>
1225
1226 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1227 <dd>This directory holds the source code for the LLVM assembly language parser
1228 library.</dd>
1229
1230 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1231 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1232
1233 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1234 different program analyses, such as Dominator Information, Call Graphs,
1235 Induction Variables, Interval Identification, Natural Loop Identification,
1236 etc.</dd>
1237
1238 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1239 <dd> This directory contains the source code for the LLVM to LLVM program
1240 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1241 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1242 Elimination, and many others.</dd>
1243
1244 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1245 <dd> This directory contains files that describe various target architectures
1246 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1247 directory holds the X86 machine description while
1248 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1249
1250 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1251 <dd> This directory contains the major parts of the code generator: Instruction
1252 Selector, Instruction Scheduling, and Register Allocation.</dd>
1253
1254 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1255 <dd> This directory contains the source level debugger library that makes
1256 it possible to instrument LLVM programs so that a debugger could identify
1257 source code locations at which the program is executing.</dd>
1258
1259 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1260 <dd> This directory contains libraries for executing LLVM bitcode directly
1261 at runtime in both interpreted and JIT compiled fashions.</dd>
1262
1263 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1264 <dd> This directory contains the source code that corresponds to the header
1265 files located in <tt>llvm/include/Support/</tt>.</dd>
1266
1267 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1268 <dd>This directory contains the operating system abstraction layer that
1269 shields LLVM from platform-specific coding.</dd>
1270</dl>
1271
1272</div>
1273
1274<!-- ======================================================================= -->
1275<div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1276<div class="doc_text">
1277 <p>This directory contains projects that are not strictly part of LLVM but are
1278 shipped with LLVM. This is also the directory where you should create your own
1279 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
Chris Lattneraf1df782008-08-11 06:13:31 +0000[diff] [blame]1280 to set up your own project.</p>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1281</div>
1282
1283<!-- ======================================================================= -->
1284<div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1285<div class="doc_text">
1286
1287<p>This directory contains libraries which are compiled into LLVM bitcode and
1288used when linking programs with the GCC front end. Most of these libraries are
1289skeleton versions of real libraries; for example, libc is a stripped down
1290version of glibc.</p>
1291
1292<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1293end to compile.</p>
1294
1295</div>
1296
1297<!-- ======================================================================= -->
1298<div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1299<div class="doc_text">
1300 <p>This directory contains feature and regression tests and other basic sanity
1301 checks on the LLVM infrastructure. These are intended to run quickly and cover
1302 a lot of territory without being exhaustive.</p>
1303</div>
1304
1305<!-- ======================================================================= -->
1306<div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1307<div class="doc_text">
1308 <p>This is not a directory in the normal llvm module; it is a separate
1309 Subversion
1310 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1311 This
1312 module contains a comprehensive correctness, performance, and benchmarking
1313 test
1314 suite for LLVM. It is a separate Subversion module because not every LLVM
1315 user is
1316 interested in downloading or building such a comprehensive test suite. For
1317 further details on this test suite, please see the
1318 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1319</div>
1320
1321<!-- ======================================================================= -->
1322<div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1323<div class="doc_text">
1324
1325<p>The <b>tools</b> directory contains the executables built out of the
1326libraries above, which form the main part of the user interface. You can
1327always get help for a tool by typing <tt>tool_name --help</tt>. The
1328following is a brief introduction to the most important tools. More detailed
1329information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1330
1331<dl>
1332
1333 <dt><tt><b>bugpoint</b></tt></dt>
1334 <dd><tt>bugpoint</tt> is used to debug
1335 optimization passes or code generation backends by narrowing down the
1336 given test case to the minimum number of passes and/or instructions that
1337 still cause a problem, whether it is a crash or miscompilation. See <a
1338 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1339 on using <tt>bugpoint</tt>.</dd>
1340
1341 <dt><tt><b>llvmc</b></tt></dt>
1342 <dd>The LLVM Compiler Driver. This program can
1343 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1344 pre-processing, translation, optimization, assembly, and linking of programs
1345 all from one command line. <tt>llvmc</tt> also takes care of processing the
1346 dependent libraries found in bitcode. This reduces the need to get the
1347 traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1348 note that this tool, while functional, is still experimental and not feature
1349 complete.</dd>
1350
1351 <dt><tt><b>llvm-ar</b></tt></dt>
1352 <dd>The archiver produces an archive containing
1353 the given LLVM bitcode files, optionally with an index for faster
1354 lookup.</dd>
1355
1356 <dt><tt><b>llvm-as</b></tt></dt>
1357 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1358 bitcode.</dd>
1359
1360 <dt><tt><b>llvm-dis</b></tt></dt>
1361 <dd>The disassembler transforms the LLVM bitcode to human readable
1362 LLVM assembly.</dd>
1363
1364 <dt><tt><b>llvm-ld</b></tt></dt>
1365 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1366 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1367 optimizations and allows optimization modules to be loaded and run so that
1368 language specific optimizations can be applied at link time.</dd>
1369
1370 <dt><tt><b>llvm-link</b></tt></dt>
1371 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1372 a single program.</dd>
1373
1374 <dt><tt><b>lli</b></tt></dt>
1375 <dd><tt>lli</tt> is the LLVM interpreter, which
Nick Lewycky32dc2a12007-12-03 01:58:01 +0000[diff] [blame]1376 can directly execute LLVM bitcode (although very slowly...). For architectures
1377 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1378 will function as a Just-In-Time compiler (if the functionality was compiled
1379 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1380
1381 <dt><tt><b>llc</b></tt></dt>
1382 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1383 translates LLVM bitcode to a native code assembly file or to C code (with
1384 the -march=c option).</dd>
1385
1386 <dt><tt><b>llvm-gcc</b></tt></dt>
1387 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1388 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1389 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1390 usual machine code output. It works just like any other GCC compiler,
1391 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1392 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1393 separate Subversion module.</dd>
1394
1395 <dt><tt><b>opt</b></tt></dt>
1396 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1397 transformations (which are specified on the command line), and then outputs
1398 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]1399 get a list of the program transformations available in LLVM.<br>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1400 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1401 LLVM bitcode file and print out the results. It is primarily useful for
1402 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1403</dl>
1404</div>
1405
1406<!-- ======================================================================= -->
1407<div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1408<div class="doc_text">
1409
1410<p>This directory contains utilities for working with LLVM source code, and some
1411of the utilities are actually required as part of the build process because they
1412are code generators for parts of LLVM infrastructure.</p>
1413
1414<dl>
1415 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1416 that finds differences between code that LLC generates and code that LLI
1417 generates. This is a useful tool if you are debugging one of them,
1418 assuming that the other generates correct output. For the full user
1419 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1420
1421 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1422 syntax-highlighting files which will work with Emacs and XEmacs editors,
1423 providing syntax highlighting support for LLVM assembly files and TableGen
1424 description files. For information on how to use the syntax files, consult
1425 the <tt>README</tt> file in that directory.<br><br>
1426
1427 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1428 and outputs all non-generated source files, which is useful if one wishes
1429 to do a lot of development across directories and does not want to
1430 individually find each file. One way to use it is to run, for example:
1431 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1432 tree.<br><br>
1433
1434 <dt><tt><b>llvmgrep</b></tt></dt>
1435 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1436 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1437 line. This is a very efficient way of searching the source base for a
1438 particular regular expression.</dd>
1439
1440 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1441 files in the current directory and then compiles and links the tool that
1442 is the first argument. For example, assuming you are in the directory
1443 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1444 simply running <tt>makellvm llc</tt> will make a build of the current
1445 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1446 causing a re-linking of LLC.<br><br>
1447
1448 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1449 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1450 cron script to generate nightly status reports of the functionality of
1451 tools, and the results can be seen by following the appropriate link on
1452 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1453
1454 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1455 the tool used to generate register descriptions, instruction set
1456 descriptions, and even assemblers from common TableGen description
1457 files.<br><br>
1458
1459 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1460 syntax-highlighting files which will work with the VIM editor, providing
1461 syntax highlighting support for LLVM assembly files and TableGen
1462 description files. For information on how to use the syntax files, consult
1463 the <tt>README</tt> file in that directory.<br><br>
1464
1465</dl>
1466
1467</div>
1468
1469<!-- ======================================================================= -->
1470<div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1471<div class="doc_text">
1472 <p>This directory contains build scripts and project files for use with
1473 Visual C++. This allows developers on Windows to build LLVM without the need
1474 for Cygwin. The contents of this directory should be considered experimental
1475 at this time.
1476 </p>
1477</div>
1478<!-- *********************************************************************** -->
1479<div class="doc_section">
1480 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1481</div>
1482<!-- *********************************************************************** -->
1483
1484<div class="doc_text">
1485<p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
Chris Lattnere6099642009-04-10 15:38:51 +0000[diff] [blame]1486so we only include instructions for llvm-gcc4.
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1487</p>
1488
1489<p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1490from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1491create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1492the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1493<i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1494output.</p>
1495</div>
1496
1497<!-- ======================================================================= -->
1498<div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1499
1500<div class="doc_text">
1501
1502<ol>
1503 <li><p>First, create a simple C file, name it 'hello.c':</p>
1504
1505<div class="doc_code">
1506<pre>
1507#include &lt;stdio.h&gt;
1508
1509int main() {
1510 printf("hello world\n");
1511 return 0;
1512}
1513</pre></div></li>
1514
1515 <li><p>Next, compile the C file into a native executable:</p>
1516
1517 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1518
1519 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1520 -c arguments work as usual (producing a native .s or .o file,
1521 respectively).</p></li>
1522
1523 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1524
1525 <div class="doc_code">
1526 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1527
1528 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1529 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1530 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1531 the bitcode file.</p>
1532
1533 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1534 </p></li>
1535
1536 <li><p>Run the program in both forms. To run the program, use:</p>
1537
1538 <div class="doc_code"><pre>% ./hello</pre></div>
1539
1540 <p>and</p>
1541
1542 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1543
1544 <p>The second examples shows how to invoke the LLVM JIT, <a
1545 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1546
1547 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1548 code:</p>
1549
1550<div class="doc_code">
1551<pre>llvm-dis &lt; hello.bc | less</pre>
1552</div></li>
1553
1554 <li><p>Compile the program to native assembly using the LLC code
1555 generator:</p>
1556
1557 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1558
1559 <li><p>Assemble the native assembly language file into a program:</p>
1560
1561<div class="doc_code">
1562<pre>
1563<b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1564
1565<b>Others:</b> % gcc hello.s -o hello.native
1566</pre>
1567</div></li>
1568
1569 <li><p>Execute the native code program:</p>
1570
1571 <div class="doc_code"><pre>% ./hello.native</pre></div>
1572
1573 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1574 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1575 </li>
1576
1577</ol>
1578
1579</div>
1580
1581
1582<!-- *********************************************************************** -->
1583<div class="doc_section">
1584 <a name="problems">Common Problems</a>
1585</div>
1586<!-- *********************************************************************** -->
1587
1588<div class="doc_text">
1589
1590<p>If you are having problems building or using LLVM, or if you have any other
1591general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1592Asked Questions</a> page.</p>
1593
1594</div>
1595
1596<!-- *********************************************************************** -->
1597<div class="doc_section">
1598 <a name="links">Links</a>
1599</div>
1600<!-- *********************************************************************** -->
1601
1602<div class="doc_text">
1603
Bill Wendling08f49b92008-07-22 01:10:25 +0000[diff] [blame]1604<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]1605some simple things... there are many more interesting and complicated things
1606that you can do that aren't documented here (but we'll gladly accept a patch
1607if you want to write something up!). For more information about LLVM, check
1608out:</p>
1609
1610<ul>
1611 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1612 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1613 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1614 that Uses LLVM</a></li>
1615</ul>
1616
1617</div>
1618
1619<!-- *********************************************************************** -->
1620
1621<hr>
1622<address>
1623 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman947321d2008-12-11 17:34:48 +0000[diff] [blame]1624 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Dan Gohmanf17a25c2007-07-18 16:29:46 +0000[diff] [blame]1625 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman5c1cc642008-12-11 18:23:24 +0000[diff] [blame]1626 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]1627
1628 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1629 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1630 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1631 Last modified: $Date$
1632</address>
1633</body>
1634</html>