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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 and other tools</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 Subversion</a>
31 <li><a href="#installcf">Install the GCC Front End</a>
32 <li><a href="#config">Local LLVM Configuration</a>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
34 <li><a href="#cross-compile">Cross-Compiling LLVM</a>
35 <li><a href="#objfiles">The Location of LLVM Object Files</a>
36 <li><a href="#optionalconfig">Optional Configuration Items</a>
39 <li><a href="#layout">Program layout</a>
41 <li><a href="#examples"><tt>llvm/examples</tt></a>
42 <li><a href="#include"><tt>llvm/include</tt></a>
43 <li><a href="#lib"><tt>llvm/lib</tt></a>
44 <li><a href="#projects"><tt>llvm/projects</tt></a>
45 <li><a href="#runtime"><tt>llvm/runtime</tt></a>
46 <li><a href="#test"><tt>llvm/test</tt></a>
47 <li><a href="#llvmtest"><tt>llvm-test</tt></a>
48 <li><a href="#tools"><tt>llvm/tools</tt></a>
49 <li><a href="#utils"><tt>llvm/utils</tt></a>
50 <li><a href="#win32"><tt>llvm/win32</tt></a>
53 <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
55 <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
57 <li><a href="#problems">Common Problems</a>
58 <li><a href="#links">Links</a>
61 <div class="doc_author">
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>.
72 <!-- *********************************************************************** -->
73 <div class="doc_section">
74 <a name="overview"><b>Overview</b></a>
76 <!-- *********************************************************************** -->
78 <div class="doc_text">
80 <p>Welcome to LLVM! In order to get started, you first need to know some
81 basic information.</p>
83 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
84 contains all of the tools, libraries, and header files needed to use the low
85 level virtual machine. It contains an assembler, disassembler, bytecode
86 analyzer and bytecode optimizer. It also contains a test suite that can be
87 used to test the LLVM tools and the GCC front end.</p>
89 <p>The second piece is the GCC front end. This component provides a version of
90 GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
91 end uses the GCC parser to convert code to LLVM. Once
92 compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
93 from the LLVM suite.</p>
96 There is a third, optional piece called llvm-test. It is a suite of programs
97 with a testing harness that can be used to further test LLVM's functionality
103 <!-- *********************************************************************** -->
104 <div class="doc_section">
105 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
107 <!-- *********************************************************************** -->
109 <div class="doc_text">
111 <p>Here's the short story for getting up and running quickly with LLVM:</p>
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>
117 <li>Install the GCC front end if you intend to compile C or C++:
119 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
120 <li><tt>gunzip --stdout llvm-gcc.<i>platform</i>.tar.gz | tar -xvf -</tt>
122 <li><tt>cd llvm-gcc3.4/<i>platform</i> (llvm-gcc3.4 only)<br>
123 ./fixheaders</tt></li>
124 <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
127 <li>Get the LLVM Source Code
129 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
131 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
132 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
137 <li><b>[Optional]</b> Get the Test Suite Source Code
139 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
141 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
142 <li><tt>cd llvm/projects</tt>
143 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
149 <li>Configure the LLVM Build Environment
151 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
152 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
156 <li><tt>--prefix=<i>directory</i></tt>
157 <p>Specify for <i>directory</i> the full pathname of where you
158 want the LLVM tools and libraries to be installed (default
159 <tt>/usr/local</tt>).</p></li>
160 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
161 <p>Optionally, specify for <i>directory</i> the full pathname of the
162 C/C++ front end installation to use with this LLVM configuration. If
163 not specified, the PATH will be searched.</p></li>
164 <li><tt>--enable-spec2000=<i>directory</i></tt>
165 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
166 benchmarks should be available in
167 <tt><i>directory</i></tt>.</p></li>
171 <li>Build the LLVM Suite:
173 <li><tt>gmake -k |& tee gnumake.out
174 # 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>
181 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
182 detailed information on configuring and compiling LLVM. See <a
183 href="#environment">Setting Up Your Environment</a> for tips that simplify
184 working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
185 Layout</a> to learn about the layout of the source code tree.</p>
189 <!-- *********************************************************************** -->
190 <div class="doc_section">
191 <a name="requirements"><b>Requirements</b></a>
193 <!-- *********************************************************************** -->
195 <div class="doc_text">
197 <p>Before you begin to use the LLVM system, review the requirements given below.
198 This may save you some trouble by knowing ahead of time what hardware and
199 software you will need.</p>
203 <!-- ======================================================================= -->
204 <div class="doc_subsection">
205 <a name="hardware"><b>Hardware</b></a>
208 <div class="doc_text">
210 <p>LLVM is known to work on the following platforms:</p>
212 <table cellpadding="3" summary="Known LLVM platforms">
220 <td>x86<sup><a href="#pf_1">1</a></sup></td>
225 <td>V9 (Ultrasparc)</td>
230 <td>x86<sup><a href="#pf_1">1</a></sup></td>
234 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
239 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
245 <td>Cygwin/Win32</td>
246 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
247 <td>GCC 3.4.X, binutils 2.15</td>
251 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
252 <td>GCC 3.4.X, binutils 2.15</td>
256 <td>amd64<sup><a href="#pf_3">3</a></sup></td>
261 <p>LLVM has partial support for the following platforms:</p>
263 <table summary="LLVM partial platform support">
271 <td>x86<sup><a href="#pf_1">1</a></sup></td>
272 <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
274 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
279 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
285 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
290 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
291 <td>Itanium (IA-64)</td>
295 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
296 <td>Itanium (IA-64)</td>
303 <div class="doc_notes">
305 <li><a name="pf_1">Code generation supported for Pentium processors and
307 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
308 <li><a name="pf_3">No native code generation</a></li>
309 <li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
310 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
311 <li><a name="pf_6">The port is done using the MSYS shell.</a>
312 <a href="http://www.mingw.org/MinGWiki/">Download</a> and install
313 bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
314 if necessary. Bison & flex can be also grabbed from GNUWin32 sf.net
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>
326 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
327 mode, depending on the system (it is so large because of all the debugging
328 information and the fact that the libraries are statically linked into multiple
329 tools). If you do not need many of the tools and you are space-conscious,
330 you can disable them individually in <tt>llvm/tools/Makefile</tt>. The Release
331 build requires considerably less space.</p>
333 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
334 guaranteed to do so. If compilation is successful, the LLVM utilities should be
335 able to assemble, disassemble, analyze, and optimize LLVM bytecode. Code
336 generation should work as well, although the generated native code may not work
337 on your platform.</p>
339 <p>The GCC front end is not very portable at the moment. If you want to get it
340 to work on another platform, you can download a copy of the source and <a
341 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
345 <!-- ======================================================================= -->
346 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
347 <div class="doc_text">
348 <p>Compiling LLVM requires that you have several software packages
349 installed. The table below lists those required packages. The Package column
350 is the usual name for the software package that LLVM depends on. The Version
351 column provides "known to work" versions of the package. The Notes column
352 describes how LLVM uses the package and provides other details.</p>
353 <table summary="Packages required to compile LLVM">
354 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
357 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
358 <td>3.79, 3.79.1</td>
359 <td>Makefile/build processor</td>
363 <td><a href="http://gcc.gnu.org">GCC</a></td>
365 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
369 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
371 <td>For building the CFE</td>
375 <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
377 <td>LEX compiler</td>
381 <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
382 <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
383 <td>YACC compiler</td>
387 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
389 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
393 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
395 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
399 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
401 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
405 <td><a href="http://expect.nist.gov/">expect</a></td>
407 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
411 <td><a href="http://www.perl.com/download.csp">perl</a></td>
413 <td>Nightly tester, utilities</td>
417 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
419 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
423 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
425 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
429 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
431 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
435 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
437 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
443 <div class="doc_notes">
445 <li><a name="sf1">Only the C and C++ languages are needed so there's no
446 need to build the other languages for LLVM's purposes.</a> See
447 <a href="#brokengcc">below</a> for specific version info.</li>
448 <li><a name="sf2">You only need Subversion if you intend to build from the
449 latest LLVM sources. If you're working from a release distribution, you
450 don't need Subversion.</a></li>
451 <li><a name="sf3">Only needed if you want to run the automated test
452 suite in the <tt>llvm/test</tt> directory.</a></li>
453 <li><a name="sf4">If you want to make changes to the configure scripts,
454 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
455 or higher). You will also need automake (1.9.2). We only use aclocal
456 from that package.</a></li>
460 <p>Additionally, your compilation host is expected to have the usual
461 plethora of Unix utilities. Specifically:</p>
463 <li><b>ar</b> - archive library builder</li>
464 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
465 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
466 <li><b>chmod</b> - change permissions on a file</li>
467 <li><b>cat</b> - output concatenation utility</li>
468 <li><b>cp</b> - copy files</li>
469 <li><b>date</b> - print the current date/time </li>
470 <li><b>echo</b> - print to standard output</li>
471 <li><b>egrep</b> - extended regular expression search utility</li>
472 <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
473 <li><b>find</b> - find files/dirs in a file system</li>
474 <li><b>grep</b> - regular expression search utility</li>
475 <li><b>gzip*</b> - gzip command for distribution generation</li>
476 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
477 <li><b>install</b> - install directories/files </li>
478 <li><b>mkdir</b> - create a directory</li>
479 <li><b>mv</b> - move (rename) files</li>
480 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
481 <li><b>rm</b> - remove (delete) files and directories</li>
482 <li><b>sed</b> - stream editor for transforming output</li>
483 <li><b>sh</b> - Bourne shell for make build scripts</li>
484 <li><b>tar</b> - tape archive for distribution generation</li>
485 <li><b>test</b> - test things in file system</li>
486 <li><b>unzip*</b> - unzip command for distribution checking</li>
487 <li><b>zip*</b> - zip command for distribution generation</li>
491 <!-- ======================================================================= -->
492 <div class="doc_subsection">
493 <a name="brokengcc">Broken versions of GCC and other tools</a>
496 <div class="doc_text">
498 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
499 bugs in the compiler. In particular, several versions of GCC crash when trying
500 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
501 successfully with them (however, see important notes below). Other versions
502 of GCC will probably work as well. GCC versions listed
503 here are known to not work. If you are using one of these versions, please try
504 to upgrade your GCC to something more recent. If you run into a problem with a
505 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
506 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
507 of GCC you are using.
510 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
511 problems in the STL that effectively prevent it from compiling LLVM.
514 <p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
516 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
517 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
518 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
520 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
521 Cygwin does not work. Please <a href="CFEBuildInstrs.html#cygwin">upgrade
522 to a newer version</a> if possible.</p>
523 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
524 possibly others) does not compile LLVM correctly (it appears that exception
525 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
526 to a newer version of GCC.</p>
527 <p><b>GCC 3.4.0</b> on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
528 code generator, causing an infinite loop in the llvm-gcc build when built
529 with optimizations enabled (i.e. a release build).</p>
530 <p><b>GCC 3.4.2</b> on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
531 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
532 correctly compiles LLVM at -O2. A work around is to build release LLVM
533 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
534 <p><b>GCC 3.4.x</b> on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
535 miscompiles portions of LLVM</a>.</p>
536 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
538 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
539 default with ENABLE_OPTIMIZED=1. To work around this, build with
540 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
541 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
542 compiling some files. At the time of this writing, GCC mainline (4.2)
543 did not share the problem.</p>
544 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
545 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
546 code. LLVM will appear to mostly work but will be buggy, e.g. failing
547 portions of its testsuite.</p>
548 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
549 platforms compiling md5.c gets a mangled constant.</p>
550 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
551 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
552 defined in a discarded section. You can safely ignore these messages as they are
553 erroneous and the linkage is correct. These messages disappear using ld
556 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
557 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
558 causes huge link times (minutes instead of seconds) when building LLVM. We
559 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
565 <!-- *********************************************************************** -->
566 <div class="doc_section">
567 <a name="starting"><b>Getting Started with LLVM</b></a>
569 <!-- *********************************************************************** -->
571 <div class="doc_text">
573 <p>The remainder of this guide is meant to get you up and running with
574 LLVM and to give you some basic information about the LLVM environment.</p>
576 <p>The later sections of this guide describe the <a
577 href="#layout">general layout</a> of the the LLVM source tree, a <a
578 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
579 href="#links">links</a> to find more information about LLVM or to get
583 <!-- ======================================================================= -->
584 <div class="doc_subsection">
585 <a name="terminology">Terminology and Notation</a>
588 <div class="doc_text">
590 <p>Throughout this manual, the following names are used to denote paths
591 specific to the local system and working environment. <i>These are not
592 environment variables you need to set but just strings used in the rest
593 of this document below</i>. In any of the examples below, simply replace
594 each of these names with the appropriate pathname on your local system.
595 All these paths are absolute:</p>
600 This is the top level directory of the LLVM source tree.
605 This is the top level directory of the LLVM object tree (i.e. the
606 tree where object files and compiled programs will be placed. It
607 can be the same as SRC_ROOT).
612 This is where the LLVM GCC Front End is installed.
614 For the pre-built GCC front end binaries, the LLVMGCCDIR is
615 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
620 <!-- ======================================================================= -->
621 <div class="doc_subsection">
622 <a name="environment">Setting Up Your Environment</a>
625 <div class="doc_text">
628 In order to compile and use LLVM, you may need to set some environment
632 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bytecode/libs</tt></dt>
633 <dd>[Optional] This environment variable helps LLVM linking tools find the
634 locations of your bytecode libraries. It is provided only as a
635 convenience since you can specify the paths using the -L options of the
636 tools and the C/C++ front-end will automatically use the bytecode files
638 <tt>lib</tt> directory.</dd>
643 <!-- ======================================================================= -->
644 <div class="doc_subsection">
645 <a name="unpack">Unpacking the LLVM Archives</a>
648 <div class="doc_text">
651 If you have the LLVM distribution, you will need to unpack it before you
652 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
653 suite and the LLVM GCC front end compiled for your platform. There is an
654 additional test suite that is optional. Each file is a TAR archive that is
655 compressed with the gzip program.
658 <p>The files are as follows, with <em>x.y</em> marking the version number:
660 <dt><tt>llvm-x.y.tar.gz</tt></dt>
661 <dd>Source release for the LLVM libraries and tools.<br/></dd>
663 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
664 <dd>Source release for the LLVM test suite.</dd>
666 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
667 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
668 directory for build instructions.<br/></dd>
670 <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
671 <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
675 <p>It is also possible to download the sources of the llvm-gcc4 front end from a
676 read-only subversion mirror at
677 svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
681 <!-- ======================================================================= -->
682 <div class="doc_subsection">
683 <a name="checkout">Checkout LLVM from Subversion</a>
686 <div class="doc_text">
688 <p>If you have access to our Subversion repository, you can get a fresh copy of
689 the entire source code. All you need to do is check it out from Subvresion as
693 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
694 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
695 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
700 <p>This will create an '<tt>llvm</tt>' directory in the current
701 directory and fully populate it with the LLVM source code, Makefiles,
702 test directories, and local copies of documentation files.</p>
704 <p>If you want to get a specific release (as opposed to the most recent
705 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
706 '<tt>trunk</tt>'). The following releases have the following labels:</p>
709 <li>Release 2.0: <b>RELEASE_20</b></li>
710 <li>Release 1.9: <b>RELEASE_19</b></li>
711 <li>Release 1.8: <b>RELEASE_18</b></li>
712 <li>Release 1.7: <b>RELEASE_17</b></li>
713 <li>Release 1.6: <b>RELEASE_16</b></li>
714 <li>Release 1.5: <b>RELEASE_15</b></li>
715 <li>Release 1.4: <b>RELEASE_14</b></li>
716 <li>Release 1.3: <b>RELEASE_13</b></li>
717 <li>Release 1.2: <b>RELEASE_12</b></li>
718 <li>Release 1.1: <b>RELEASE_11</b></li>
719 <li>Release 1.0: <b>RELEASE_1</b></li>
722 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
723 you get it from the Subversion repository:</p>
726 svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite
728 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
729 configured by the LLVM configure script as well as automatically updated when
730 you run <tt>svn update</tt>.</p>
732 <p>If you would like to get the GCC front end source code, you can also get it
733 and build it yourself. Please follow <a href="CFEBuildInstrs.html">these
734 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
738 <!-- ======================================================================= -->
739 <div class="doc_subsection">
740 <a name="installcf">Install the GCC Front End</a>
743 <div class="doc_text">
745 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
746 LLVM GCC front end from the binary distribution. It is used for running the
747 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
748 <a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
749 main LLVM repository.</p>
751 <p>To install the GCC front end, do the following:</p>
754 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
755 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
759 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
760 llvm-g++ to some directory in your path. When you configure LLVM, it will
761 automatically detect llvm-gcc's presence (if it is in your path) enabling its
762 use in llvm-test. Note that you can always build or install llvm-gcc at any
763 pointer after building the main LLVM repository: just reconfigure llvm and
764 llvm-test will pick it up.
767 <p>The binary versions of the GCC front end may not suit all of your needs. For
768 example, the binary distribution may include an old version of a system header
769 file, not "fix" a header file that needs to be fixed for GCC, or it may be
770 linked with libraries not available on your system.</p>
772 <p>In cases like these, you may want to try <a
773 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
774 much easier now than it was in the past.</p>
778 <!-- ======================================================================= -->
779 <div class="doc_subsection">
780 <a name="config">Local LLVM Configuration</a>
783 <div class="doc_text">
785 <p>Once checked out from the Subversion repository, the LLVM suite source
787 configured via the <tt>configure</tt> script. This script sets variables in the
788 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
789 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
790 the Makefiles needed to begin building LLVM.</p>
792 <p>The following environment variables are used by the <tt>configure</tt>
793 script to configure the build system:</p>
795 <table summary="LLVM configure script environment variables">
796 <tr><th>Variable</th><th>Purpose</th></tr>
799 <td>Tells <tt>configure</tt> which C compiler to use. By default,
800 <tt>configure</tt> will look for the first GCC C compiler in
801 <tt>PATH</tt>. Use this variable to override
802 <tt>configure</tt>'s default behavior.</td>
806 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
807 <tt>configure</tt> will look for the first GCC C++ compiler in
808 <tt>PATH</tt>. Use this variable to override
809 <tt>configure</tt>'s default behavior.</td>
813 <p>The following options can be used to set or enable LLVM specific options:</p>
816 <dt><i>--with-llvmgccdir</i></dt>
817 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
818 The value of this option should specify the full pathname of the C/C++ Front
819 End to be used. If this option is not provided, the PATH will be searched for
820 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
821 be inferred from the path found. If the option is not given, and no llvm-gcc
822 can be found in the path then a warning will be produced by
823 <tt>configure</tt> indicating this situation. LLVM may still be built with
824 the <tt>tools-only</tt> target but attempting to build the runtime libraries
825 will fail as these libraries require llvm-gcc and llvm-g++. See
826 <a href="#installcf">Install the GCC Front End</a> for details on installing
827 the C/C++ Front End. See
828 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
829 for details on building the C/C++ Front End.</dd>
830 <dt><i>--with-tclinclude</i></dt>
831 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
832 found. Use this if you have multiple tcl installations on your machine and you
833 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
834 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
835 option, the LLVM configure script will search for the tcl 8.4 and 8.3
839 <dt><i>--enable-optimized</i></dt>
841 Enables optimized compilation by default (debugging symbols are removed
842 and GCC optimization flags are enabled). The default is to use an
843 unoptimized build (also known as a debug build).
846 <dt><i>--enable-debug-runtime</i></dt>
848 Enables debug symbols in the runtime libraries. The default is to strip
849 debug symbols from the runtime libraries.
851 <dt><i>--enable-jit</i></dt>
853 Compile the Just In Time (JIT) compiler functionality. This is not
855 on all platforms. The default is dependent on platform, so it is best
856 to explicitly enable it if you want it.
859 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
860 <dd>Controls which targets will be built and linked into llc. The default
861 value for <tt>target_options</tt> is "all" which builds and links all
862 available targets. The value "host-only" can be specified to build only a
863 native compiler (no cross-compiler targets available). The "native" target is
864 selected as the target of the build host. You can also specify a comma
865 separated list of target names that you want available in llc. The target
866 names use all lower case. The current set of targets is: <br/>
867 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
869 <dt><i>--enable-doxygen</i></dt>
870 <dd>Look for the doxygen program and enable construction of doxygen based
871 documentation from the source code. This is disabled by default because
872 generating the documentation can take a long time and producess 100s of
873 megabytes of output.</dd>
874 <dt><i>--with-udis86</i></dt>
875 <dd>LLVM can use external disassembler library for various purposes (now it's
876 used only for examining code produced by JIT). This option will enable usage
877 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
878 bits) disassembler library.</dd>
881 <p>To configure LLVM, follow these steps:</p>
884 <li>Change directory into the object root directory:
886 <tt>cd <i>OBJ_ROOT</i></tt>
889 <li>Run the <tt>configure</tt> script located in the LLVM source tree:
891 <tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
897 <!-- ======================================================================= -->
898 <div class="doc_subsection">
899 <a name="compile">Compiling the LLVM Suite Source Code</a>
902 <div class="doc_text">
904 <p>Once you have configured LLVM, you can build it. There are three types of
910 These builds are the default when one types <tt>gmake</tt> (unless the
911 <tt>--enable-optimized</tt> option was used during configuration). The
912 build system will compile the tools and libraries with debugging
916 <dt>Release (Optimized) Builds
918 These builds are enabled with the <tt>--enable-optimized</tt> option to
919 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
920 <tt>gmake</tt> command line. For these builds, the build system will
921 compile the tools and libraries with GCC optimizations enabled and strip
922 debugging information from the libraries and executables it generates.
927 These builds are for use with profiling. They compile profiling
928 information into the code for use with programs like <tt>gprof</tt>.
929 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
930 on the <tt>gmake</tt> command line.
933 <p>Once you have LLVM configured, you can build it by entering the
934 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
936 <p><tt>gmake</tt></p>
938 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
939 are using a version of GCC that is known not to compile LLVM.</p>
942 If you have multiple processors in your machine, you may wish to use some of
943 the parallel build options provided by GNU Make. For example, you could use the
946 <p><tt>gmake -j2</tt></p>
948 <p>There are several special targets which are useful when working with the LLVM
952 <dt><tt>gmake clean</tt>
954 Removes all files generated by the build. This includes object files,
955 generated C/C++ files, libraries, and executables.
958 <dt><tt>gmake dist-clean</tt>
960 Removes everything that <tt>gmake clean</tt> does, but also removes files
961 generated by <tt>configure</tt>. It attempts to return the source tree to the
962 original state in which it was shipped.
965 <dt><tt>gmake install</tt>
967 Installs LLVM header files, libraries, tools, and documentation in a
969 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
970 defaults to <tt>/usr/local</tt>.
973 <dt><tt>gmake -C runtime install-bytecode</tt>
975 Assuming you built LLVM into $OBJDIR, when this command is run, it will
976 install bytecode libraries into the GCC front end's bytecode library
977 directory. If you need to update your bytecode libraries,
978 this is the target to use once you've built them.
982 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
983 details on these <tt>make</tt> targets and descriptions of other targets
986 <p>It is also possible to override default values from <tt>configure</tt> by
987 declaring variables on the command line. The following are some examples:</p>
990 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
992 Perform a Release (Optimized) build.
995 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
997 Perform a Release (Optimized) build without assertions enabled.
1000 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1002 Perform a Profiling build.
1005 <dt><tt>gmake VERBOSE=1</tt>
1007 Print what <tt>gmake</tt> is doing on standard output.
1010 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1011 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1012 the standard output. This also implies <tt>VERBOSE=1</tt>.
1016 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1017 it and any subdirectories that it contains. Entering any directory inside the
1018 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1019 that directory that is out of date.</p>
1023 <!-- ======================================================================= -->
1024 <div class="doc_subsection">
1025 <a name="cross-compile">Cross-Compiling LLVM</a>
1028 <div class="doc_text">
1029 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1030 executables and libraries for a platform different than the one one which you
1031 are compiling. To do this, a few additional steps are
1032 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1033 these instructions:</p>
1035 <li>Configure and build LLVM as a native compiler. You will need
1036 just <tt>TableGen</tt> from that build.
1038 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1039 <tt>make -C utils/TableGen</tt> after configuring.</li>
1040 <li>Otherwise you will need to monitor building process and terminate
1041 it just after <tt>TableGen</tt> was built.</li>
1044 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1046 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1047 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1048 are different. The values of these options must be legal target triples
1049 that your GCC compiler supports.</li>
1050 <li>Put the saved <tt>TableGen</tt> executable into the
1051 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1052 <tt>.../Release/bin</tt> for a Release build).</li>
1053 <li>Build LLVM as usual.</li>
1055 <p>The result of such a build will produce executables that are not executable
1056 on your build host (--build option) but can be executed on your compile host
1057 (--host option).</p>
1058 <p><b>Notes:</b></p>
1059 <div class="doc_notes">
1061 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1062 build platform and Windows as host using mingw32 cross-compiler. Other
1063 combinations have not been tested.</li>
1068 <!-- ======================================================================= -->
1069 <div class="doc_subsection">
1070 <a name="objfiles">The Location of LLVM Object Files</a>
1073 <div class="doc_text">
1075 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1076 several LLVM builds. Hence, it is possible to build LLVM for several different
1077 platforms or configurations using the same source tree.</p>
1079 <p>This is accomplished in the typical autoconf manner:</p>
1082 <li><p>Change directory to where the LLVM object files should live:</p>
1084 <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
1086 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1089 <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
1092 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1093 named after the build type:</p>
1100 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1102 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1110 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1112 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1120 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1122 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1128 <!-- ======================================================================= -->
1129 <div class="doc_subsection">
1130 <a name="optionalconfig">Optional Configuration Items</a>
1133 <div class="doc_text">
1136 If you're running on a Linux system that supports the "<a
1137 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">
1139 module, and you have root access on the system, you can set your system up to
1140 execute LLVM bytecode files directly. To do this, use commands like this (the
1141 first command may not be required if you are already using the module):</p>
1143 <div class="doc_code">
1145 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1146 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1147 $ chmod u+x hello.bc (if needed)
1153 This allows you to execute LLVM bytecode files directly. Thanks to Jack
1154 Cummings for pointing this out!
1160 <!-- *********************************************************************** -->
1161 <div class="doc_section">
1162 <a name="layout"><b>Program Layout</b></a>
1164 <!-- *********************************************************************** -->
1166 <div class="doc_text">
1168 <p>One useful source of information about the LLVM source base is the LLVM <a
1169 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1170 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1171 The following is a brief introduction to code layout:</p>
1175 <!-- ======================================================================= -->
1176 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1177 <div class="doc_text">
1178 <p>This directory contains some simple examples of how to use the LLVM IR and
1182 <!-- ======================================================================= -->
1183 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1184 <div class="doc_text">
1186 <p>This directory contains public header files exported from the LLVM
1187 library. The three main subdirectories of this directory are:</p>
1190 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1191 <dd>This directory contains all of the LLVM specific header files. This
1192 directory also has subdirectories for different portions of LLVM:
1193 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1196 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1197 <dd>This directory contains generic support libraries that are provided with
1198 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1199 and a Command Line option processing library store their header files here.
1202 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1203 <dd>This directory contains header files configured by the <tt>configure</tt>
1204 script. They wrap "standard" UNIX and C header files. Source code can
1205 include these header files which automatically take care of the conditional
1206 #includes that the <tt>configure</tt> script generates.</dd>
1210 <!-- ======================================================================= -->
1211 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1212 <div class="doc_text">
1214 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1215 almost all code exists in libraries, making it very easy to share code among the
1216 different <a href="#tools">tools</a>.</p>
1219 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1220 <dd> This directory holds the core LLVM source files that implement core
1221 classes like Instruction and BasicBlock.</dd>
1223 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1224 <dd>This directory holds the source code for the LLVM assembly language parser
1227 <dt><tt><b>llvm/lib/ByteCode/</b></tt></dt>
1228 <dd>This directory holds code for reading and write LLVM bytecode.</dd>
1230 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1231 different program analyses, such as Dominator Information, Call Graphs,
1232 Induction Variables, Interval Identification, Natural Loop Identification,
1235 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1236 <dd> This directory contains the source code for the LLVM to LLVM program
1237 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1238 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1239 Elimination, and many others.</dd>
1241 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1242 <dd> This directory contains files that describe various target architectures
1243 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1244 directory holds the X86 machine description while
1245 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1247 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1248 <dd> This directory contains the major parts of the code generator: Instruction
1249 Selector, Instruction Scheduling, and Register Allocation.</dd>
1251 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1252 <dd> This directory contains the source level debugger library that makes
1253 it possible to instrument LLVM programs so that a debugger could identify
1254 source code locations at which the program is executing.</dd>
1256 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1257 <dd> This directory contains libraries for executing LLVM bytecode directly
1258 at runtime in both interpreted and JIT compiled fashions.</dd>
1260 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1261 <dd> This directory contains the source code that corresponds to the header
1262 files located in <tt>llvm/include/Support/</tt>.</dd>
1264 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1265 <dd>This directory contains the operating system abstraction layer that
1266 shields LLVM from platform-specific coding.</dd>
1271 <!-- ======================================================================= -->
1272 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1273 <div class="doc_text">
1274 <p>This directory contains projects that are not strictly part of LLVM but are
1275 shipped with LLVM. This is also the directory where you should create your own
1276 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1277 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1278 functional example of a compiler front end.</p>
1281 <!-- ======================================================================= -->
1282 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1283 <div class="doc_text">
1285 <p>This directory contains libraries which are compiled into LLVM bytecode and
1286 used when linking programs with the GCC front end. Most of these libraries are
1287 skeleton versions of real libraries; for example, libc is a stripped down
1288 version of glibc.</p>
1290 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1295 <!-- ======================================================================= -->
1296 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1297 <div class="doc_text">
1298 <p>This directory contains feature and regression tests and other basic sanity
1299 checks on the LLVM infrastructure. These are intended to run quickly and cover
1300 a lot of territory without being exhaustive.</p>
1303 <!-- ======================================================================= -->
1304 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1305 <div class="doc_text">
1306 <p>This is not a directory in the normal llvm module; it is a separate
1308 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1310 module contains a comprehensive correctness, performance, and benchmarking
1312 suite for LLVM. It is a separate Subversion module because not every LLVM
1314 interested in downloading or building such a comprehensive test suite. For
1315 further details on this test suite, please see the
1316 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1319 <!-- ======================================================================= -->
1320 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1321 <div class="doc_text">
1323 <p>The <b>tools</b> directory contains the executables built out of the
1324 libraries above, which form the main part of the user interface. You can
1325 always get help for a tool by typing <tt>tool_name --help</tt>. The
1326 following is a brief introduction to the most important tools. More detailed
1327 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1331 <dt><tt><b>bugpoint</b></tt></dt>
1332 <dd><tt>bugpoint</tt> is used to debug
1333 optimization passes or code generation backends by narrowing down the
1334 given test case to the minimum number of passes and/or instructions that
1335 still cause a problem, whether it is a crash or miscompilation. See <a
1336 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1337 on using <tt>bugpoint</tt>.</dd>
1339 <dt><tt><b>llvmc</b></tt></dt>
1340 <dd>The LLVM Compiler Driver. This program can
1341 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1342 pre-processing, translation, optimization, assembly, and linking of programs
1343 all from one command line. <tt>llvmc</tt> also takes care of processing the
1344 dependent libraries found in bytecode. This reduces the need to get the
1345 traditional <tt>-l<name></tt> options right on the command line. Please
1346 note that this tool, while functional, is still experimental and not feature
1349 <dt><tt><b>llvm-ar</b></tt></dt>
1350 <dd>The archiver produces an archive containing
1351 the given LLVM bytecode files, optionally with an index for faster
1354 <dt><tt><b>llvm-as</b></tt></dt>
1355 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1358 <dt><tt><b>llvm-dis</b></tt></dt>
1359 <dd>The disassembler transforms the LLVM bytecode to human readable
1362 <dt><tt><b>llvm-ld</b></tt></dt>
1363 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1364 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1365 optimizations and allows optimization modules to be loaded and run so that
1366 language specific optimizations can be applied at link time.</dd>
1368 <dt><tt><b>llvm-link</b></tt></dt>
1369 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1370 a single program.</dd>
1372 <dt><tt><b>lli</b></tt></dt>
1373 <dd><tt>lli</tt> is the LLVM interpreter, which
1374 can directly execute LLVM bytecode (although very slowly...). In addition
1375 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1376 specifying <tt>-trace</tt> on the command line). Finally, for
1377 architectures that support it (currently x86, Sparc, and PowerPC), by default,
1378 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1379 functionality was compiled in), and will execute the code <i>much</i>
1380 faster than the interpreter.</dd>
1382 <dt><tt><b>llc</b></tt></dt>
1383 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1384 translates LLVM bytecode to a native code assembly file or to C code (with
1385 the -march=c option).</dd>
1387 <dt><tt><b>llvm-gcc</b></tt></dt>
1388 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1389 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1390 byte code or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1391 usual machine code output. It works just like any other GCC compiler,
1392 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1393 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1394 separate Subversion module.</dd>
1396 <dt><tt><b>opt</b></tt></dt>
1397 <dd><tt>opt</tt> reads LLVM bytecode, applies a series of LLVM to LLVM
1398 transformations (which are specified on the command line), and then outputs
1399 the resultant bytecode. The '<tt>opt --help</tt>' command is a good way to
1400 get a list of the program transformations available in LLVM.<br/>
1401 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1402 LLVM bytecode file and print out the results. It is primarily useful for
1403 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1407 <!-- ======================================================================= -->
1408 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1409 <div class="doc_text">
1411 <p>This directory contains utilities for working with LLVM source code, and some
1412 of the utilities are actually required as part of the build process because they
1413 are code generators for parts of LLVM infrastructure.</p>
1416 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1417 that finds differences between code that LLC generates and code that LLI
1418 generates. This is a useful tool if you are debugging one of them,
1419 assuming that the other generates correct output. For the full user
1420 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1422 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1423 syntax-highlighting files which will work with Emacs and XEmacs editors,
1424 providing syntax highlighting support for LLVM assembly files and TableGen
1425 description files. For information on how to use the syntax files, consult
1426 the <tt>README</tt> file in that directory.<br><br>
1428 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1429 and outputs all non-generated source files, which is useful if one wishes
1430 to do a lot of development across directories and does not want to
1431 individually find each file. One way to use it is to run, for example:
1432 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1435 <dt><tt><b>llvmgrep</b></tt></dt>
1436 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1437 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1438 line. This is a very efficient way of searching the source base for a
1439 particular regular expression.</dd>
1441 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1442 files in the current directory and then compiles and links the tool that
1443 is the first argument. For example, assuming you are in the directory
1444 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1445 simply running <tt>makellvm llc</tt> will make a build of the current
1446 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1447 causing a re-linking of LLC.<br><br>
1449 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1450 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1451 cron script to generate nightly status reports of the functionality of
1452 tools, and the results can be seen by following the appropriate link on
1453 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1455 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1456 the tool used to generate register descriptions, instruction set
1457 descriptions, and even assemblers from common TableGen description
1460 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1461 syntax-highlighting files which will work with the VIM editor, providing
1462 syntax highlighting support for LLVM assembly files and TableGen
1463 description files. For information on how to use the syntax files, consult
1464 the <tt>README</tt> file in that directory.<br><br>
1470 <!-- ======================================================================= -->
1471 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1472 <div class="doc_text">
1473 <p>This directory contains build scripts and project files for use with
1474 Visual C++. This allows developers on Windows to build LLVM without the need
1475 for Cygwin. The contents of this directory should be considered experimental
1479 <!-- *********************************************************************** -->
1480 <div class="doc_section">
1481 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1483 <!-- *********************************************************************** -->
1485 <div class="doc_text">
1486 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1487 so we only include instructiosn for llvm-gcc4.
1490 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1491 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1492 create bytecode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1493 the '--emit-llvm' flag is needed to produce LLVM bytecode output. For <i>makefiles</i> and
1494 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bytecode
1498 <!-- ======================================================================= -->
1499 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1501 <div class="doc_text">
1504 <li>First, create a simple C file, name it 'hello.c':
1506 #include <stdio.h>
1508 printf("hello world\n");
1513 <li><p>Next, compile the C file into a native executable:</p>
1515 <p><tt>% llvm-gcc hello.c -o hello</tt></p>
1517 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1518 -c arguments work as usual (producing a native .s or .o file,
1521 <li><p>Next, compile the C file into a LLVM bytecode file:</p>
1522 <p><tt>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</tt></p>
1524 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1525 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1526 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1527 the bytecode file.</p>
1529 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1532 <li><p>Run the program in both forms. To run the program, use:</p>
1534 <p><tt>% ./hello</tt></p>
1538 <p><tt>% lli hello.bc</tt></p>
1540 <p>The second examples shows how to invoke the LLVM JIT, <a
1541 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1543 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1546 <p><tt>% llvm-dis < hello.bc | less</tt><br><br></li>
1548 <li><p>Compile the program to native assembly using the LLC code
1551 <p><tt>% llc hello.bc -o hello.s</tt></p>
1553 <li><p>Assemble the native assembly language file into a program:</p>
1555 <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1556 <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1558 <li><p>Execute the native code program:</p>
1560 <p><tt>% ./hello.native</tt></p>
1562 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1563 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1571 <!-- *********************************************************************** -->
1572 <div class="doc_section">
1573 <a name="problems">Common Problems</a>
1575 <!-- *********************************************************************** -->
1577 <div class="doc_text">
1579 <p>If you are having problems building or using LLVM, or if you have any other
1580 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1581 Asked Questions</a> page.</p>
1585 <!-- *********************************************************************** -->
1586 <div class="doc_section">
1587 <a name="links">Links</a>
1589 <!-- *********************************************************************** -->
1591 <div class="doc_text">
1593 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1594 some simple things... there are many more interesting and complicated things
1595 that you can do that aren't documented here (but we'll gladly accept a patch
1596 if you want to write something up!). For more information about LLVM, check
1600 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1601 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1602 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1603 that Uses LLVM</a></li>
1608 <!-- *********************************************************************** -->
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1617 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1618 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1619 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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