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11 <div class="doc_title">
12 Getting Started with the LLVM System
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>
20 <li><a href="#hardware">Hardware</a>
21 <li><a href="#software">Software</a>
22 <li><a href="#brokengcc">Broken versions of GCC</a>
25 <li><a href="#starting">Getting Started with LLVM</a>
27 <li><a href="#terminology">Terminology and Notation</a>
28 <li><a href="#environment">Setting Up Your Environment</a>
29 <li><a href="#unpack">Unpacking the LLVM Archives</a>
30 <li><a href="#checkout">Checkout LLVM from CVS</a>
31 <li><a href="#installcf">Install the GCC Front End</a>
32 <li><a href="#config">Local LLVM Configuration</a>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
34 <li><a href="#cross-compile">Cross-Compiling LLVM</a>
35 <li><a href="#objfiles">The Location of LLVM Object Files</a>
36 <li><a href="#optionalconfig">Optional Configuration Items</a>
39 <li><a href="#layout">Program layout</a>
41 <li><a href="#cvsdir"><tt>CVS</tt> directories</a>
42 <li><a href="#examples"><tt>llvm/examples</tt></a>
43 <li><a href="#include"><tt>llvm/include</tt></a>
44 <li><a href="#lib"><tt>llvm/lib</tt></a>
45 <li><a href="#projects"><tt>llvm/projects</tt></a>
46 <li><a href="#runtime"><tt>llvm/runtime</tt></a>
47 <li><a href="#test"><tt>llvm/test</tt></a>
48 <li><a href="#llvmtest"><tt>llvm-test</tt></a>
49 <li><a href="#tools"><tt>llvm/tools</tt></a>
50 <li><a href="#utils"><tt>llvm/utils</tt></a>
51 <li><a href="#win32"><tt>llvm/win32</tt></a>
54 <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
56 <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
58 <li><a href="#problems">Common Problems</a>
59 <li><a href="#links">Links</a>
62 <div class="doc_author">
64 <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
65 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
66 <a href="http://misha.brukman.net">Misha Brukman</a>,
67 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
68 <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
73 <!-- *********************************************************************** -->
74 <div class="doc_section">
75 <a name="overview"><b>Overview</b></a>
77 <!-- *********************************************************************** -->
79 <div class="doc_text">
81 <p>Welcome to LLVM! In order to get started, you first need to know some
82 basic information.</p>
84 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
85 contains all of the tools, libraries, and header files needed to use the low
86 level virtual machine. It contains an assembler, disassembler, bytecode
87 analyzer and bytecode optimizer. It also contains a test suite that can be
88 used to test the LLVM tools and the GCC front end.</p>
90 <p>The second piece is the GCC front end. This component provides a version of
91 GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
92 end uses the GCC parser to convert code to LLVM. Once
93 compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
94 from the LLVM suite.</p>
97 There is a third, optional piece called llvm-test. It is a suite of programs
98 with a testing harness that can be used to further test LLVM's functionality
104 <!-- *********************************************************************** -->
105 <div class="doc_section">
106 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
108 <!-- *********************************************************************** -->
110 <div class="doc_text">
112 <p>Here's the short story for getting up and running quickly with LLVM:</p>
115 <li>Read the documentation.</li>
116 <li>Read the documentation.</li>
117 <li>Remember that you were warned twice about reading the documentation.</li>
118 <li>Install the GCC front end if you intend to compile C or C++:
120 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
121 <li><tt>gunzip --stdout llvm-gcc.<i>platform</i>.tar.gz | tar -xvf -</tt>
123 <li><tt>cd llvm-gcc3.4/<i>platform</i> (llvm-gcc3.4 only)<br>
124 ./fixheaders</tt></li>
125 <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
128 <li>Get the LLVM Source Code
130 <li>With the distributed files (or use <a href="#checkout">CVS</a>):
132 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
133 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
138 <li><b>[Optional]</b> Get the Test Suite Source Code
140 <li>With the distributed files (or use <a href="#checkout">CVS</a>):
142 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
143 <li><tt>cd llvm/projects</tt>
144 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
150 <li>Configure the LLVM Build Environment
152 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
153 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
157 <li><tt>--prefix=<i>directory</i></tt>
158 <p>Specify for <i>directory</i> the full pathname of where you
159 want the LLVM tools and libraries to be installed (default
160 <tt>/usr/local</tt>).</p></li>
161 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
162 <p>Optionally, specify for <i>directory</i> the full pathname of the
163 C/C++ front end installation to use with this LLVM configuration. If
164 not specified, the PATH will be searched.</p></li>
165 <li><tt>--enable-spec2000=<i>directory</i></tt>
166 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
167 benchmarks should be available in
168 <tt><i>directory</i></tt>.</p></li>
172 <li>Build the LLVM Suite:
174 <li><tt>gmake -k |& tee gnumake.out
175 # this is csh or tcsh syntax</tt></li>
176 <li>If you get an "internal compiler error (ICE)" or test failures, see
177 <a href="#brokengcc">below</a>.</li>
182 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
183 detailed information on configuring and compiling LLVM. See <a
184 href="#environment">Setting Up Your Environment</a> for tips that simplify
185 working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
186 Layout</a> to learn about the layout of the source code tree.</p>
190 <!-- *********************************************************************** -->
191 <div class="doc_section">
192 <a name="requirements"><b>Requirements</b></a>
194 <!-- *********************************************************************** -->
196 <div class="doc_text">
198 <p>Before you begin to use the LLVM system, review the requirements given below.
199 This may save you some trouble by knowing ahead of time what hardware and
200 software you will need.</p>
204 <!-- ======================================================================= -->
205 <div class="doc_subsection">
206 <a name="hardware"><b>Hardware</b></a>
209 <div class="doc_text">
211 <p>LLVM is known to work on the following platforms:</p>
213 <table cellpadding="3" summary="Known LLVM platforms">
221 <td>x86<sup><a href="#pf_1">1</a></sup></td>
226 <td>V9 (Ultrasparc)</td>
231 <td>x86<sup><a href="#pf_1">1</a></sup></td>
235 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
240 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
246 <td>Cygwin/Win32</td>
247 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
248 <td>GCC 3.4.X, binutils 2.15</td>
252 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
253 <td>GCC 3.4.X, binutils 2.15</td>
257 <td>amd64<sup><a href="#pf_3">3</a></sup></td>
262 <p>LLVM has partial support for the following platforms:</p>
264 <table summary="LLVM partial platform support">
272 <td>x86<sup><a href="#pf_1">1</a></sup></td>
273 <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
275 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
280 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
286 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
291 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
292 <td>Itanium (IA-64)</td>
296 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
297 <td>Itanium (IA-64)</td>
304 <div class="doc_notes">
306 <li><a name="pf_1">Code generation supported for Pentium processors and
308 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
309 <li><a name="pf_3">No native code generation</a></li>
310 <li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
311 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
312 <li><a name="pf_6">The port is done using the MSYS shell.</a>
313 <a href="http://www.mingw.org/MinGWiki/">Download</a> and install
314 bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
315 if necessary. Bison & flex can be also grabbed from GNUWin32 sf.net
317 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
318 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
319 preventing LLVM from building correctly. Several workarounds have been
320 introduced into LLVM build system, but the bug can occur anytime in the
321 future. We highly recommend that you rebuild your current binutils with the
322 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
323 Binutils bugzilla</a>, if it wasn't already applied.</li>
327 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
328 mode, depending on the system (it is so large because of all the debugging
329 information and the fact that the libraries are statically linked into multiple
330 tools). If you do not need many of the tools and you are space-conscious,
331 you can disable them individually in <tt>llvm/tools/Makefile</tt>. The Release
332 build requires considerably less space.</p>
334 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
335 guaranteed to do so. If compilation is successful, the LLVM utilities should be
336 able to assemble, disassemble, analyze, and optimize LLVM bytecode. Code
337 generation should work as well, although the generated native code may not work
338 on your platform.</p>
340 <p>The GCC front end is not very portable at the moment. If you want to get it
341 to work on another platform, you can download a copy of the source and <a
342 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
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>
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>
364 <td><a href="http://gcc.gnu.org">GCC</a></td>
366 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
370 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
372 <td>For building the CFE</td>
376 <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
378 <td>LEX compiler</td>
382 <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
383 <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
384 <td>YACC compiler</td>
388 <td><a href="https://www.cvshome.org/downloads.html">CVS</a></td>
390 <td>CVS access to LLVM<sup><a href="#sf2">2</a></sup></td>
394 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
396 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
400 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
402 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
406 <td><a href="http://expect.nist.gov/">expect</a></td>
408 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
412 <td><a href="http://www.perl.com/download.csp">perl</a></td>
414 <td>Nightly tester, utilities</td>
418 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
420 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
424 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
426 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
430 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
432 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
436 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
438 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
444 <div class="doc_notes">
446 <li><a name="sf1">Only the C and C++ languages are needed so there's no
447 need to build the other languages for LLVM's purposes.</a> See
448 <a href="#brokengcc">below</a> for specific version info.</li>
449 <li><a name="sf2">You only need CVS if you intend to build from the
450 latest LLVM sources. If you're working from a release distribution, you
451 don't need CVS.</a></li>
452 <li><a name="sf3">Only needed if you want to run the automated test
453 suite in the <tt>llvm/test</tt> directory.</a></li>
454 <li><a name="sf4">If you want to make changes to the configure scripts,
455 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
456 or higher). You will also need automake (1.9.2). We only use aclocal
457 from that package.</a></li>
461 <p>Additionally, your compilation host is expected to have the usual
462 plethora of Unix utilities. Specifically:</p>
464 <li><b>ar</b> - archive library builder</li>
465 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
466 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
467 <li><b>chmod</b> - change permissions on a file</li>
468 <li><b>cat</b> - output concatenation utility</li>
469 <li><b>cp</b> - copy files</li>
470 <li><b>date</b> - print the current date/time </li>
471 <li><b>echo</b> - print to standard output</li>
472 <li><b>egrep</b> - extended regular expression search utility</li>
473 <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
474 <li><b>find</b> - find files/dirs in a file system</li>
475 <li><b>grep</b> - regular expression search utility</li>
476 <li><b>gzip*</b> - gzip command for distribution generation</li>
477 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
478 <li><b>install</b> - install directories/files </li>
479 <li><b>mkdir</b> - create a directory</li>
480 <li><b>mv</b> - move (rename) files</li>
481 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
482 <li><b>rm</b> - remove (delete) files and directories</li>
483 <li><b>sed</b> - stream editor for transforming output</li>
484 <li><b>sh</b> - Bourne shell for make build scripts</li>
485 <li><b>tar</b> - tape archive for distribution generation</li>
486 <li><b>test</b> - test things in file system</li>
487 <li><b>unzip*</b> - unzip command for distribution checking</li>
488 <li><b>zip*</b> - zip command for distribution generation</li>
492 <!-- ======================================================================= -->
493 <div class="doc_subsection">
494 <a name="brokengcc">Broken versions of GCC</a>
497 <div class="doc_text">
499 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
500 bugs in the compiler. In particular, several versions of GCC crash when trying
501 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
502 successfully with them (however, see below). Other versions of GCC will
503 probably work as well. GCC versions listed
504 here are known to not work. If you are using one of these versions, please try
505 to upgrade your GCC to something more recent. If you run into a problem with a
506 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
507 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
508 of GCC you are using.
511 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
512 problems in the STL that effectively prevent it from compiling LLVM.
515 <p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
517 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
518 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
519 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
521 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
522 Cygwin does not work. Please <a href="CFEBuildInstrs.html#cygwin">upgrade
523 to a newer version</a> if possible.</p>
524 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
525 possibly others) does not compile LLVM correctly (it appears that exception
526 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
527 to a newer version of GCC.</p>
528 <p><b>GCC 3.4.x</b> on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
529 miscompiles portions of LLVM</a>.</p>
530 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
532 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
533 default with ENABLE_OPTIMIZED=1. To work around this, build with
534 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
535 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
536 compiling some files. At the time of this writing, GCC mainline (4.2)
537 did not share the problem.</p>
538 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
539 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
540 code. LLVM will appear to mostly work but will be buggy, e.g. failing
541 portions of its testsuite.</p>
542 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
543 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
544 defined in a discarded section. You can safely ignore these messages as they are
545 erroneous and the linkage is correct. These messages disappear using ld
551 <!-- *********************************************************************** -->
552 <div class="doc_section">
553 <a name="starting"><b>Getting Started with LLVM</b></a>
555 <!-- *********************************************************************** -->
557 <div class="doc_text">
559 <p>The remainder of this guide is meant to get you up and running with
560 LLVM and to give you some basic information about the LLVM environment.</p>
562 <p>The later sections of this guide describe the <a
563 href="#layout">general layout</a> of the the LLVM source tree, a <a
564 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
565 href="#links">links</a> to find more information about LLVM or to get
569 <!-- ======================================================================= -->
570 <div class="doc_subsection">
571 <a name="terminology">Terminology and Notation</a>
574 <div class="doc_text">
576 <p>Throughout this manual, the following names are used to denote paths
577 specific to the local system and working environment. <i>These are not
578 environment variables you need to set but just strings used in the rest
579 of this document below</i>. In any of the examples below, simply replace
580 each of these names with the appropriate pathname on your local system.
581 All these paths are absolute:</p>
586 This is the top level directory of the LLVM source tree.
591 This is the top level directory of the LLVM object tree (i.e. the
592 tree where object files and compiled programs will be placed. It
593 can be the same as SRC_ROOT).
598 This is where the LLVM GCC Front End is installed.
600 For the pre-built GCC front end binaries, the LLVMGCCDIR is
601 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
606 <!-- ======================================================================= -->
607 <div class="doc_subsection">
608 <a name="environment">Setting Up Your Environment</a>
611 <div class="doc_text">
614 In order to compile and use LLVM, you may need to set some environment
618 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bytecode/libs</tt></dt>
619 <dd>[Optional] This environment variable helps LLVM linking tools find the
620 locations of your bytecode libraries. It is provided only as a
621 convenience since you can specify the paths using the -L options of the
622 tools and the C/C++ front-end will automatically use the bytecode files
624 <tt>lib</tt> directory.</dd>
629 <!-- ======================================================================= -->
630 <div class="doc_subsection">
631 <a name="unpack">Unpacking the LLVM Archives</a>
634 <div class="doc_text">
637 If you have the LLVM distribution, you will need to unpack it before you
638 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
639 suite and the LLVM GCC front end compiled for your platform. There is an
640 additional test suite that is optional. Each file is a TAR archive that is
641 compressed with the gzip program.
644 <p>The files are as follows, with <em>x.y</em> marking the version number:
646 <dt><tt>llvm-x.y.tar.gz</tt></dt>
647 <dd>Source release for the LLVM libraries and tools.<br/></dd>
649 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
650 <dd>Source release for the LLVM test suite.</dd>
652 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
653 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
654 directory for build instructions.<br/></dd>
656 <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
657 <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
661 <p>It is also possible to download the sources of the llvm-gcc4 front end from a
662 read-only subversion mirror at
663 svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
667 <!-- ======================================================================= -->
668 <div class="doc_subsection">
669 <a name="checkout">Checkout LLVM from CVS</a>
672 <div class="doc_text">
674 <p>If you have access to our CVS repository, you can get a fresh copy of
675 the entire source code. All you need to do is check it out from CVS as
679 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
680 <li><tt>cvs -d :pserver:anon@llvm.org:/var/cvs/llvm login</tt>
681 <li>Hit the return key when prompted for the password.
682 <li><tt>cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co
686 <p>This will create an '<tt>llvm</tt>' directory in the current
687 directory and fully populate it with the LLVM source code, Makefiles,
688 test directories, and local copies of documentation files.</p>
690 <p>If you want to get a specific release (as opposed to the most recent
691 revision), you can specify a label. The following releases have the following
695 <li>Release 1.9: <b>RELEASE_19</b></li>
696 <li>Release 1.8: <b>RELEASE_18</b></li>
697 <li>Release 1.7: <b>RELEASE_17</b></li>
698 <li>Release 1.6: <b>RELEASE_16</b></li>
699 <li>Release 1.5: <b>RELEASE_15</b></li>
700 <li>Release 1.4: <b>RELEASE_14</b></li>
701 <li>Release 1.3: <b>RELEASE_13</b></li>
702 <li>Release 1.2: <b>RELEASE_12</b></li>
703 <li>Release 1.1: <b>RELEASE_11</b></li>
704 <li>Release 1.0: <b>RELEASE_1</b></li>
707 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
708 you get it from the CVS repository:</p>
711 cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-test
713 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
714 configured by the LLVM configure script as well as automatically updated when
715 you run <tt>cvs update</tt>.</p>
717 <p>If you would like to get the GCC front end source code, you can also get it
718 and build it yourself. Please follow <a href="CFEBuildInstrs.html">these
719 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
723 <!-- ======================================================================= -->
724 <div class="doc_subsection">
725 <a name="installcf">Install the GCC Front End</a>
728 <div class="doc_text">
730 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
731 LLVM GCC front end from the binary distribution. It is used for running the
732 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
733 <a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
734 main LLVM repository.</p>
736 <p>To install the GCC front end, do the following:</p>
739 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
740 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
744 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
745 llvm-g++ to some directory in your path. When you configure LLVM, it will
746 automatically detect llvm-gcc's presence (if it is in your path) enabling its
747 use in llvm-test. Note that you can always build or install llvm-gcc at any
748 pointer after building the main LLVM repository: just reconfigure llvm and
749 llvm-test will pick it up.
752 <p>The binary versions of the GCC front end may not suit all of your needs. For
753 example, the binary distribution may include an old version of a system header
754 file, not "fix" a header file that needs to be fixed for GCC, or it may be
755 linked with libraries not available on your system.</p>
757 <p>In cases like these, you may want to try <a
758 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
759 much easier now than it was in the past.</p>
763 <!-- ======================================================================= -->
764 <div class="doc_subsection">
765 <a name="config">Local LLVM Configuration</a>
768 <div class="doc_text">
770 <p>Once checked out from the CVS repository, the LLVM suite source code must be
771 configured via the <tt>configure</tt> script. This script sets variables in the
772 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
773 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
774 the Makefiles needed to begin building LLVM.</p>
776 <p>The following environment variables are used by the <tt>configure</tt>
777 script to configure the build system:</p>
779 <table summary="LLVM configure script environment variables">
780 <tr><th>Variable</th><th>Purpose</th></tr>
783 <td>Tells <tt>configure</tt> which C compiler to use. By default,
784 <tt>configure</tt> will look for the first GCC C compiler in
785 <tt>PATH</tt>. Use this variable to override
786 <tt>configure</tt>'s default behavior.</td>
790 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
791 <tt>configure</tt> will look for the first GCC C++ compiler in
792 <tt>PATH</tt>. Use this variable to override
793 <tt>configure</tt>'s default behavior.</td>
797 <p>The following options can be used to set or enable LLVM specific options:</p>
800 <dt><i>--with-llvmgccdir</i></dt>
801 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
802 The value of this option should specify the full pathname of the C/C++ Front
803 End to be used. If this option is not provided, the PATH will be searched for
804 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
805 be inferred from the path found. If the option is not given, and no llvm-gcc
806 can be found in the path then a warning will be produced by
807 <tt>configure</tt> indicating this situation. LLVM may still be built with
808 the <tt>tools-only</tt> target but attempting to build the runtime libraries
809 will fail as these libraries require llvm-gcc and llvm-g++. See
810 <a href="#installcf">Install the GCC Front End</a> for details on installing
811 the C/C++ Front End. See
812 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
813 for details on building the C/C++ Front End.</dd>
814 <dt><i>--with-tclinclude</i></dt>
815 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
816 found. Use this if you have multiple tcl installations on your machine and you
817 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
818 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
819 option, the LLVM configure script will search for the tcl 8.4 and 8.3
823 <dt><i>--enable-optimized</i></dt>
825 Enables optimized compilation by default (debugging symbols are removed
826 and GCC optimization flags are enabled). The default is to use an
827 unoptimized build (also known as a debug build).
830 <dt><i>--enable-debug-runtime</i></dt>
832 Enables debug symbols in the runtime libraries. The default is to strip
833 debug symbols from the runtime libraries.
835 <dt><i>--enable-jit</i></dt>
837 Compile the Just In Time (JIT) compiler functionality. This is not
839 on all platforms. The default is dependent on platform, so it is best
840 to explicitly enable it if you want it.
843 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
844 <dd>Controls which targets will be built and linked into llc. The default
845 value for <tt>target_options</tt> is "all" which builds and links all
846 available targets. The value "host-only" can be specified to build only a
847 native compiler (no cross-compiler targets available). The "native" target is
848 selected as the target of the build host. You can also specify a comma
849 separated list of target names that you want available in llc. The target
850 names use all lower case. The current set of targets is: <br/>
851 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
853 <dt><i>--enable-doxygen</i></dt>
854 <dd>Look for the doxygen program and enable construction of doxygen based
855 documentation from the source code. This is disabled by default because
856 generating the documentation can take a long time and producess 100s of
857 megabytes of output.</dd>
858 <dt><i>--with-udis86</i></dt>
859 <dd>LLVM can use external disassembler library for various purposes (now it's
860 used only for examining code produced by JIT). This option will enable usage
861 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
862 bits) disassembler library.</dd>
865 <p>To configure LLVM, follow these steps:</p>
868 <li>Change directory into the object root directory:
870 <tt>cd <i>OBJ_ROOT</i></tt>
873 <li>Run the <tt>configure</tt> script located in the LLVM source tree:
875 <tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
881 <!-- ======================================================================= -->
882 <div class="doc_subsection">
883 <a name="compile">Compiling the LLVM Suite Source Code</a>
886 <div class="doc_text">
888 <p>Once you have configured LLVM, you can build it. There are three types of
894 These builds are the default when one types <tt>gmake</tt> (unless the
895 <tt>--enable-optimized</tt> option was used during configuration). The
896 build system will compile the tools and libraries with debugging
900 <dt>Release (Optimized) Builds
902 These builds are enabled with the <tt>--enable-optimized</tt> option to
903 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
904 <tt>gmake</tt> command line. For these builds, the build system will
905 compile the tools and libraries with GCC optimizations enabled and strip
906 debugging information from the libraries and executables it generates.
911 These builds are for use with profiling. They compile profiling
912 information into the code for use with programs like <tt>gprof</tt>.
913 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
914 on the <tt>gmake</tt> command line.
917 <p>Once you have LLVM configured, you can build it by entering the
918 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
920 <p><tt>gmake</tt></p>
922 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
923 are using a version of GCC that is known not to compile LLVM.</p>
926 If you have multiple processors in your machine, you may wish to use some of
927 the parallel build options provided by GNU Make. For example, you could use the
930 <p><tt>gmake -j2</tt></p>
932 <p>There are several special targets which are useful when working with the LLVM
936 <dt><tt>gmake clean</tt>
938 Removes all files generated by the build. This includes object files,
939 generated C/C++ files, libraries, and executables.
942 <dt><tt>gmake dist-clean</tt>
944 Removes everything that <tt>gmake clean</tt> does, but also removes files
945 generated by <tt>configure</tt>. It attempts to return the source tree to the
946 original state in which it was shipped.
949 <dt><tt>gmake install</tt>
951 Installs LLVM header files, libraries, tools, and documentation in a
953 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
954 defaults to <tt>/usr/local</tt>.
957 <dt><tt>gmake -C runtime install-bytecode</tt>
959 Assuming you built LLVM into $OBJDIR, when this command is run, it will
960 install bytecode libraries into the GCC front end's bytecode library
961 directory. If you need to update your bytecode libraries,
962 this is the target to use once you've built them.
966 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
967 details on these <tt>make</tt> targets and descriptions of other targets
970 <p>It is also possible to override default values from <tt>configure</tt> by
971 declaring variables on the command line. The following are some examples:</p>
974 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
976 Perform a Release (Optimized) build.
979 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
981 Perform a Release (Optimized) build without assertions enabled.
984 <dt><tt>gmake ENABLE_PROFILING=1</tt>
986 Perform a Profiling build.
989 <dt><tt>gmake VERBOSE=1</tt>
991 Print what <tt>gmake</tt> is doing on standard output.
994 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
995 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
996 the standard output. This also implies <tt>VERBOSE=1</tt>.
1000 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1001 it and any subdirectories that it contains. Entering any directory inside the
1002 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1003 that directory that is out of date.</p>
1007 <!-- ======================================================================= -->
1008 <div class="doc_subsection">
1009 <a name="cross-compile">Cross-Compiling LLVM</a>
1012 <div class="doc_text">
1013 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1014 executables and libraries for a platform different than the one one which you
1015 are compiling. To do this, a few additional steps are
1016 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1017 these instructions:</p>
1019 <li>Configure and build LLVM as a native compiler. You will need
1020 just <tt>TableGen</tt> from that build.
1022 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1023 <tt>make -C utils/TableGen</tt> after configuring.</li>
1024 <li>Otherwise you will need to monitor building process and terminate
1025 it just after <tt>TableGen</tt> was built.</li>
1028 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1030 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1031 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1032 are different. The values of these options must be legal target triples
1033 that your GCC compiler supports.</li>
1034 <li>Put the saved <tt>TableGen</tt> executable into the
1035 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1036 <tt>.../Release/bin</tt> for a Release build).</li>
1037 <li>Build LLVM as usual.</li>
1039 <p>The result of such a build will produce executables that are not executable
1040 on your build host (--build option) but can be executed on your compile host
1041 (--host option).</p>
1042 <p><b>Notes:</b></p>
1043 <div class="doc_notes">
1045 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1046 build platform and Windows as host using mingw32 cross-compiler. Other
1047 combinations have not been tested.</li>
1052 <!-- ======================================================================= -->
1053 <div class="doc_subsection">
1054 <a name="objfiles">The Location of LLVM Object Files</a>
1057 <div class="doc_text">
1059 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1060 several LLVM builds. Hence, it is possible to build LLVM for several different
1061 platforms or configurations using the same source tree.</p>
1063 <p>This is accomplished in the typical autoconf manner:</p>
1066 <li><p>Change directory to where the LLVM object files should live:</p>
1068 <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
1070 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1073 <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
1076 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1077 named after the build type:</p>
1084 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1086 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1094 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1096 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1104 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1106 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1112 <!-- ======================================================================= -->
1113 <div class="doc_subsection">
1114 <a name="optionalconfig">Optional Configuration Items</a>
1117 <div class="doc_text">
1120 If you're running on a Linux system that supports the "<a
1121 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">
1123 module, and you have root access on the system, you can set your system up to
1124 execute LLVM bytecode files directly. To do this, use commands like this (the
1125 first command may not be required if you are already using the module):</p>
1127 <div class="doc_code">
1129 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1130 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1131 $ chmod u+x hello.bc (if needed)
1137 This allows you to execute LLVM bytecode files directly. Thanks to Jack
1138 Cummings for pointing this out!
1144 <!-- *********************************************************************** -->
1145 <div class="doc_section">
1146 <a name="layout"><b>Program Layout</b></a>
1148 <!-- *********************************************************************** -->
1150 <div class="doc_text">
1152 <p>One useful source of information about the LLVM source base is the LLVM <a
1153 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1154 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1155 The following is a brief introduction to code layout:</p>
1159 <!-- ======================================================================= -->
1160 <div class="doc_subsection"><a name="cvsdir"><tt>CVS</tt> directories</a></div>
1161 <div class="doc_text">
1162 <p>Every directory checked out of CVS will contain a <tt>CVS</tt> directory; for
1163 the most part these can just be ignored.</p>
1166 <!-- ======================================================================= -->
1167 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1168 <div class="doc_text">
1169 <p>This directory contains some simple examples of how to use the LLVM IR and
1173 <!-- ======================================================================= -->
1174 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1175 <div class="doc_text">
1177 <p>This directory contains public header files exported from the LLVM
1178 library. The three main subdirectories of this directory are:</p>
1181 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1182 <dd>This directory contains all of the LLVM specific header files. This
1183 directory also has subdirectories for different portions of LLVM:
1184 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1187 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1188 <dd>This directory contains generic support libraries that are provided with
1189 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1190 and a Command Line option processing library store their header files here.
1193 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1194 <dd>This directory contains header files configured by the <tt>configure</tt>
1195 script. They wrap "standard" UNIX and C header files. Source code can
1196 include these header files which automatically take care of the conditional
1197 #includes that the <tt>configure</tt> script generates.</dd>
1201 <!-- ======================================================================= -->
1202 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1203 <div class="doc_text">
1205 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1206 almost all code exists in libraries, making it very easy to share code among the
1207 different <a href="#tools">tools</a>.</p>
1210 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1211 <dd> This directory holds the core LLVM source files that implement core
1212 classes like Instruction and BasicBlock.</dd>
1214 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1215 <dd>This directory holds the source code for the LLVM assembly language parser
1218 <dt><tt><b>llvm/lib/ByteCode/</b></tt></dt>
1219 <dd>This directory holds code for reading and write LLVM bytecode.</dd>
1221 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1222 different program analyses, such as Dominator Information, Call Graphs,
1223 Induction Variables, Interval Identification, Natural Loop Identification,
1226 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1227 <dd> This directory contains the source code for the LLVM to LLVM program
1228 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1229 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1230 Elimination, and many others.</dd>
1232 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1233 <dd> This directory contains files that describe various target architectures
1234 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1235 directory holds the X86 machine description while
1236 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1238 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1239 <dd> This directory contains the major parts of the code generator: Instruction
1240 Selector, Instruction Scheduling, and Register Allocation.</dd>
1242 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1243 <dd> This directory contains the source level debugger library that makes
1244 it possible to instrument LLVM programs so that a debugger could identify
1245 source code locations at which the program is executing.</dd>
1247 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1248 <dd> This directory contains libraries for executing LLVM bytecode directly
1249 at runtime in both interpreted and JIT compiled fashions.</dd>
1251 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1252 <dd> This directory contains the source code that corresponds to the header
1253 files located in <tt>llvm/include/Support/</tt>.</dd>
1255 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1256 <dd>This directory contains the operating system abstraction layer that
1257 shields LLVM from platform-specific coding.</dd>
1262 <!-- ======================================================================= -->
1263 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1264 <div class="doc_text">
1265 <p>This directory contains projects that are not strictly part of LLVM but are
1266 shipped with LLVM. This is also the directory where you should create your own
1267 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1268 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1269 functional example of a compiler front end.</p>
1272 <!-- ======================================================================= -->
1273 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1274 <div class="doc_text">
1276 <p>This directory contains libraries which are compiled into LLVM bytecode and
1277 used when linking programs with the GCC front end. Most of these libraries are
1278 skeleton versions of real libraries; for example, libc is a stripped down
1279 version of glibc.</p>
1281 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1286 <!-- ======================================================================= -->
1287 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1288 <div class="doc_text">
1289 <p>This directory contains feature and regression tests and other basic sanity
1290 checks on the LLVM infrastructure. These are intended to run quickly and cover
1291 a lot of territory without being exhaustive.</p>
1294 <!-- ======================================================================= -->
1295 <div class="doc_subsection"><a name="llvmtest"><tt>llvm-test</tt></a></div>
1296 <div class="doc_text">
1297 <p>This is not a directory in the normal llvm module; it is a separate CVS
1298 module that must be checked out (usually to <tt>projects/llvm-test</tt>). This
1299 module contains a comprehensive correctness, performance, and benchmarking
1301 suite for LLVM. It is a separate CVS module because not every LLVM user is
1302 interested in downloading or building such a comprehensive test suite. For
1303 further details on this test suite, please see the
1304 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1307 <!-- ======================================================================= -->
1308 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1309 <div class="doc_text">
1311 <p>The <b>tools</b> directory contains the executables built out of the
1312 libraries above, which form the main part of the user interface. You can
1313 always get help for a tool by typing <tt>tool_name --help</tt>. The
1314 following is a brief introduction to the most important tools. More detailed
1315 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1319 <dt><tt><b>bugpoint</b></tt></dt>
1320 <dd><tt>bugpoint</tt> is used to debug
1321 optimization passes or code generation backends by narrowing down the
1322 given test case to the minimum number of passes and/or instructions that
1323 still cause a problem, whether it is a crash or miscompilation. See <a
1324 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1325 on using <tt>bugpoint</tt>.</dd>
1327 <dt><tt><b>llvmc</b></tt></dt>
1328 <dd>The LLVM Compiler Driver. This program can
1329 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1330 pre-processing, translation, optimization, assembly, and linking of programs
1331 all from one command line. <tt>llvmc</tt> also takes care of processing the
1332 dependent libraries found in bytecode. This reduces the need to get the
1333 traditional <tt>-l<name></tt> options right on the command line. Please
1334 note that this tool, while functional, is still experimental and not feature
1337 <dt><tt><b>llvm-ar</b></tt></dt>
1338 <dd>The archiver produces an archive containing
1339 the given LLVM bytecode files, optionally with an index for faster
1342 <dt><tt><b>llvm-as</b></tt></dt>
1343 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1346 <dt><tt><b>llvm-dis</b></tt></dt>
1347 <dd>The disassembler transforms the LLVM bytecode to human readable
1350 <dt><tt><b>llvm-ld</b></tt></dt>
1351 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1352 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1353 optimizations and allows optimization modules to be loaded and run so that
1354 language specific optimizations can be applied at link time.</dd>
1356 <dt><tt><b>llvm-link</b></tt></dt>
1357 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1358 a single program.</dd>
1360 <dt><tt><b>lli</b></tt></dt>
1361 <dd><tt>lli</tt> is the LLVM interpreter, which
1362 can directly execute LLVM bytecode (although very slowly...). In addition
1363 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1364 specifying <tt>-trace</tt> on the command line). Finally, for
1365 architectures that support it (currently x86, Sparc, and PowerPC), by default,
1366 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1367 functionality was compiled in), and will execute the code <i>much</i>
1368 faster than the interpreter.</dd>
1370 <dt><tt><b>llc</b></tt></dt>
1371 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1372 translates LLVM bytecode to a native code assembly file or to C code (with
1373 the -march=c option).</dd>
1375 <dt><tt><b>llvm-gcc</b></tt></dt>
1376 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1377 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1378 byte code or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1379 usual machine code output. It works just like any other GCC compiler,
1380 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1381 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1382 separate CVS module.</dd>
1384 <dt><tt><b>opt</b></tt></dt>
1385 <dd><tt>opt</tt> reads LLVM bytecode, applies a series of LLVM to LLVM
1386 transformations (which are specified on the command line), and then outputs
1387 the resultant bytecode. The '<tt>opt --help</tt>' command is a good way to
1388 get a list of the program transformations available in LLVM.<br/>
1389 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1390 LLVM bytecode file and print out the results. It is primarily useful for
1391 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1395 <!-- ======================================================================= -->
1396 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1397 <div class="doc_text">
1399 <p>This directory contains utilities for working with LLVM source code, and some
1400 of the utilities are actually required as part of the build process because they
1401 are code generators for parts of LLVM infrastructure.</p>
1404 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1405 that finds differences between code that LLC generates and code that LLI
1406 generates. This is a useful tool if you are debugging one of them,
1407 assuming that the other generates correct output. For the full user
1408 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1410 <dt><tt><b>cvsupdate</b></tt> <dd><tt>cvsupdate</tt> is a script that will
1411 update your CVS tree, but produce a much cleaner and more organized output
1412 than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group
1413 together all the new and updated files and modified files in separate
1414 sections, so you can see at a glance what has changed. If you are at the
1415 top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the
1416 preferred way of updating the tree.<br><br>
1418 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1419 syntax-highlighting files which will work with Emacs and XEmacs editors,
1420 providing syntax highlighting support for LLVM assembly files and TableGen
1421 description files. For information on how to use the syntax files, consult
1422 the <tt>README</tt> file in that directory.<br><br>
1424 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1425 and outputs all non-generated source files, which is useful if one wishes
1426 to do a lot of development across directories and does not want to
1427 individually find each file. One way to use it is to run, for example:
1428 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1431 <dt><tt><b>llvmgrep</b></tt></dt>
1432 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1433 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1434 line. This is a very efficient way of searching the source base for a
1435 particular regular expression.</dd>
1437 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1438 files in the current directory and then compiles and links the tool that
1439 is the first argument. For example, assuming you are in the directory
1440 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1441 simply running <tt>makellvm llc</tt> will make a build of the current
1442 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1443 causing a re-linking of LLC.<br><br>
1445 <dt><tt><b>NightlyTest.pl</b></tt> and
1446 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1447 cron script to generate nightly status reports of the functionality of
1448 tools, and the results can be seen by following the appropriate link on
1449 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1451 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1452 the tool used to generate register descriptions, instruction set
1453 descriptions, and even assemblers from common TableGen description
1456 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1457 syntax-highlighting files which will work with the VIM editor, providing
1458 syntax highlighting support for LLVM assembly files and TableGen
1459 description files. For information on how to use the syntax files, consult
1460 the <tt>README</tt> file in that directory.<br><br>
1466 <!-- ======================================================================= -->
1467 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1468 <div class="doc_text">
1469 <p>This directory contains build scripts and project files for use with
1470 Visual C++. This allows developers on Windows to build LLVM without the need
1471 for Cygwin. The contents of this directory should be considered experimental
1475 <!-- *********************************************************************** -->
1476 <div class="doc_section">
1477 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1479 <!-- *********************************************************************** -->
1481 <div class="doc_text">
1482 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1483 so we only include instructiosn for llvm-gcc4.
1486 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1487 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1488 create bytecode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1489 the '--emit-llvm' flag is needed to produce LLVM bytecode output. For <i>makefiles</i> and
1490 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bytecode
1494 <!-- ======================================================================= -->
1495 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1497 <div class="doc_text">
1500 <li>First, create a simple C file, name it 'hello.c':
1502 #include <stdio.h>
1504 printf("hello world\n");
1509 <li><p>Next, compile the C file into a native executable:</p>
1511 <p><tt>% llvm-gcc hello.c -o hello</tt></p>
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,
1517 <li><p>Next, compile the C file into a LLVM bytecode file:</p>
1518 <p><tt>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</tt></p>
1520 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1521 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1522 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1523 the bytecode file.</p>
1525 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1528 <li><p>Run the program in both forms. To run the program, use:</p>
1530 <p><tt>% ./hello</tt></p>
1534 <p><tt>% lli hello.bc</tt></p>
1536 <p>The second examples shows how to invoke the LLVM JIT, <a
1537 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1539 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1542 <p><tt>% llvm-dis < hello.bc | less</tt><br><br></li>
1544 <li><p>Compile the program to native assembly using the LLC code
1547 <p><tt>% llc hello.bc -o hello.s</tt></p>
1549 <li><p>Assemble the native assembly language file into a program:</p>
1551 <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1552 <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1554 <li><p>Execute the native code program:</p>
1556 <p><tt>% ./hello.native</tt></p>
1558 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1559 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1567 <!-- *********************************************************************** -->
1568 <div class="doc_section">
1569 <a name="problems">Common Problems</a>
1571 <!-- *********************************************************************** -->
1573 <div class="doc_text">
1575 <p>If you are having problems building or using LLVM, or if you have any other
1576 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1577 Asked Questions</a> page.</p>
1581 <!-- *********************************************************************** -->
1582 <div class="doc_section">
1583 <a name="links">Links</a>
1585 <!-- *********************************************************************** -->
1587 <div class="doc_text">
1589 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1590 some simple things... there are many more interesting and complicated things
1591 that you can do that aren't documented here (but we'll gladly accept a patch
1592 if you want to write something up!). For more information about LLVM, check
1596 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1597 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1598 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1599 that Uses LLVM</a></li>
1604 <!-- *********************************************************************** -->
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1613 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
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1615 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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