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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, bitcode
86 analyzer and bitcode 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 bitcode. Currently, the GCC front
91 end uses the GCC parser to convert code to LLVM. Once
92 compiled into LLVM bitcode, 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 bitcode. 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/bitcode/libs</tt></dt>
633 <dd>[Optional] This environment variable helps LLVM linking tools find the
634 locations of your bitcode 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 bitcode 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 are located in the following
707 subdirectories of the '<tt>tags</tt>' directory:</p>
710 <li>Release 2.0: <b>RELEASE_20</b></li>
711 <li>Release 1.9: <b>RELEASE_19</b></li>
712 <li>Release 1.8: <b>RELEASE_18</b></li>
713 <li>Release 1.7: <b>RELEASE_17</b></li>
714 <li>Release 1.6: <b>RELEASE_16</b></li>
715 <li>Release 1.5: <b>RELEASE_15</b></li>
716 <li>Release 1.4: <b>RELEASE_14</b></li>
717 <li>Release 1.3: <b>RELEASE_13</b></li>
718 <li>Release 1.2: <b>RELEASE_12</b></li>
719 <li>Release 1.1: <b>RELEASE_11</b></li>
720 <li>Release 1.0: <b>RELEASE_1</b></li>
723 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
724 you get it from the Subversion repository:</p>
727 svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
729 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
730 configured by the LLVM configure script as well as automatically updated when
731 you run <tt>svn update</tt>.</p>
733 <p>If you would like to get the GCC front end source code, you can also get it
734 and build it yourself. Please follow <a href="CFEBuildInstrs.html">these
735 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
739 <!-- ======================================================================= -->
740 <div class="doc_subsection">
741 <a name="installcf">Install the GCC Front End</a>
744 <div class="doc_text">
746 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
747 LLVM GCC front end from the binary distribution. It is used for running the
748 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
749 <a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
750 main LLVM repository.</p>
752 <p>To install the GCC front end, do the following:</p>
755 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
756 <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
760 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
761 llvm-g++ to some directory in your path. When you configure LLVM, it will
762 automatically detect llvm-gcc's presence (if it is in your path) enabling its
763 use in llvm-test. Note that you can always build or install llvm-gcc at any
764 pointer after building the main LLVM repository: just reconfigure llvm and
765 llvm-test will pick it up.
768 <p>The binary versions of the GCC front end may not suit all of your needs. For
769 example, the binary distribution may include an old version of a system header
770 file, not "fix" a header file that needs to be fixed for GCC, or it may be
771 linked with libraries not available on your system.</p>
773 <p>In cases like these, you may want to try <a
774 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
775 much easier now than it was in the past.</p>
779 <!-- ======================================================================= -->
780 <div class="doc_subsection">
781 <a name="config">Local LLVM Configuration</a>
784 <div class="doc_text">
786 <p>Once checked out from the Subversion repository, the LLVM suite source
788 configured via the <tt>configure</tt> script. This script sets variables in the
789 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
790 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
791 the Makefiles needed to begin building LLVM.</p>
793 <p>The following environment variables are used by the <tt>configure</tt>
794 script to configure the build system:</p>
796 <table summary="LLVM configure script environment variables">
797 <tr><th>Variable</th><th>Purpose</th></tr>
800 <td>Tells <tt>configure</tt> which C compiler to use. By default,
801 <tt>configure</tt> will look for the first GCC C compiler in
802 <tt>PATH</tt>. Use this variable to override
803 <tt>configure</tt>'s default behavior.</td>
807 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
808 <tt>configure</tt> will look for the first GCC C++ compiler in
809 <tt>PATH</tt>. Use this variable to override
810 <tt>configure</tt>'s default behavior.</td>
814 <p>The following options can be used to set or enable LLVM specific options:</p>
817 <dt><i>--with-llvmgccdir</i></dt>
818 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
819 The value of this option should specify the full pathname of the C/C++ Front
820 End to be used. If this option is not provided, the PATH will be searched for
821 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
822 be inferred from the path found. If the option is not given, and no llvm-gcc
823 can be found in the path then a warning will be produced by
824 <tt>configure</tt> indicating this situation. LLVM may still be built with
825 the <tt>tools-only</tt> target but attempting to build the runtime libraries
826 will fail as these libraries require llvm-gcc and llvm-g++. See
827 <a href="#installcf">Install the GCC Front End</a> for details on installing
828 the C/C++ Front End. See
829 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
830 for details on building the C/C++ Front End.</dd>
831 <dt><i>--with-tclinclude</i></dt>
832 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
833 found. Use this if you have multiple tcl installations on your machine and you
834 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
835 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
836 option, the LLVM configure script will search for the tcl 8.4 and 8.3
840 <dt><i>--enable-optimized</i></dt>
842 Enables optimized compilation by default (debugging symbols are removed
843 and GCC optimization flags are enabled). The default is to use an
844 unoptimized build (also known as a debug build).
847 <dt><i>--enable-debug-runtime</i></dt>
849 Enables debug symbols in the runtime libraries. The default is to strip
850 debug symbols from the runtime libraries.
852 <dt><i>--enable-jit</i></dt>
854 Compile the Just In Time (JIT) compiler functionality. This is not
856 on all platforms. The default is dependent on platform, so it is best
857 to explicitly enable it if you want it.
860 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
861 <dd>Controls which targets will be built and linked into llc. The default
862 value for <tt>target_options</tt> is "all" which builds and links all
863 available targets. The value "host-only" can be specified to build only a
864 native compiler (no cross-compiler targets available). The "native" target is
865 selected as the target of the build host. You can also specify a comma
866 separated list of target names that you want available in llc. The target
867 names use all lower case. The current set of targets is: <br/>
868 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
870 <dt><i>--enable-doxygen</i></dt>
871 <dd>Look for the doxygen program and enable construction of doxygen based
872 documentation from the source code. This is disabled by default because
873 generating the documentation can take a long time and producess 100s of
874 megabytes of output.</dd>
875 <dt><i>--with-udis86</i></dt>
876 <dd>LLVM can use external disassembler library for various purposes (now it's
877 used only for examining code produced by JIT). This option will enable usage
878 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
879 bits) disassembler library.</dd>
882 <p>To configure LLVM, follow these steps:</p>
885 <li>Change directory into the object root directory:
887 <tt>cd <i>OBJ_ROOT</i></tt>
890 <li>Run the <tt>configure</tt> script located in the LLVM source tree:
892 <tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
898 <!-- ======================================================================= -->
899 <div class="doc_subsection">
900 <a name="compile">Compiling the LLVM Suite Source Code</a>
903 <div class="doc_text">
905 <p>Once you have configured LLVM, you can build it. There are three types of
911 These builds are the default when one types <tt>gmake</tt> (unless the
912 <tt>--enable-optimized</tt> option was used during configuration). The
913 build system will compile the tools and libraries with debugging
917 <dt>Release (Optimized) Builds
919 These builds are enabled with the <tt>--enable-optimized</tt> option to
920 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
921 <tt>gmake</tt> command line. For these builds, the build system will
922 compile the tools and libraries with GCC optimizations enabled and strip
923 debugging information from the libraries and executables it generates.
928 These builds are for use with profiling. They compile profiling
929 information into the code for use with programs like <tt>gprof</tt>.
930 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
931 on the <tt>gmake</tt> command line.
934 <p>Once you have LLVM configured, you can build it by entering the
935 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
937 <p><tt>gmake</tt></p>
939 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
940 are using a version of GCC that is known not to compile LLVM.</p>
943 If you have multiple processors in your machine, you may wish to use some of
944 the parallel build options provided by GNU Make. For example, you could use the
947 <p><tt>gmake -j2</tt></p>
949 <p>There are several special targets which are useful when working with the LLVM
953 <dt><tt>gmake clean</tt>
955 Removes all files generated by the build. This includes object files,
956 generated C/C++ files, libraries, and executables.
959 <dt><tt>gmake dist-clean</tt>
961 Removes everything that <tt>gmake clean</tt> does, but also removes files
962 generated by <tt>configure</tt>. It attempts to return the source tree to the
963 original state in which it was shipped.
966 <dt><tt>gmake install</tt>
968 Installs LLVM header files, libraries, tools, and documentation in a
970 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
971 defaults to <tt>/usr/local</tt>.
974 <dt><tt>gmake -C runtime install-bytecode</tt>
976 Assuming you built LLVM into $OBJDIR, when this command is run, it will
977 install bitcode libraries into the GCC front end's bitcode library
978 directory. If you need to update your bitcode libraries,
979 this is the target to use once you've built them.
983 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
984 details on these <tt>make</tt> targets and descriptions of other targets
987 <p>It is also possible to override default values from <tt>configure</tt> by
988 declaring variables on the command line. The following are some examples:</p>
991 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
993 Perform a Release (Optimized) build.
996 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
998 Perform a Release (Optimized) build without assertions enabled.
1001 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1003 Perform a Profiling build.
1006 <dt><tt>gmake VERBOSE=1</tt>
1008 Print what <tt>gmake</tt> is doing on standard output.
1011 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1012 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1013 the standard output. This also implies <tt>VERBOSE=1</tt>.
1017 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1018 it and any subdirectories that it contains. Entering any directory inside the
1019 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1020 that directory that is out of date.</p>
1024 <!-- ======================================================================= -->
1025 <div class="doc_subsection">
1026 <a name="cross-compile">Cross-Compiling LLVM</a>
1029 <div class="doc_text">
1030 <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1031 executables and libraries for a platform different than the one one which you
1032 are compiling. To do this, a few additional steps are
1033 required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1034 these instructions:</p>
1036 <li>Configure and build LLVM as a native compiler. You will need
1037 just <tt>TableGen</tt> from that build.
1039 <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1040 <tt>make -C utils/TableGen</tt> after configuring.</li>
1041 <li>Otherwise you will need to monitor building process and terminate
1042 it just after <tt>TableGen</tt> was built.</li>
1045 <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1047 <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1048 configure script with <tt>--build</tt> and <tt>--host</tt> options that
1049 are different. The values of these options must be legal target triples
1050 that your GCC compiler supports.</li>
1051 <li>Put the saved <tt>TableGen</tt> executable into the
1052 into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1053 <tt>.../Release/bin</tt> for a Release build).</li>
1054 <li>Build LLVM as usual.</li>
1056 <p>The result of such a build will produce executables that are not executable
1057 on your build host (--build option) but can be executed on your compile host
1058 (--host option).</p>
1059 <p><b>Notes:</b></p>
1060 <div class="doc_notes">
1062 <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1063 build platform and Windows as host using mingw32 cross-compiler. Other
1064 combinations have not been tested.</li>
1069 <!-- ======================================================================= -->
1070 <div class="doc_subsection">
1071 <a name="objfiles">The Location of LLVM Object Files</a>
1074 <div class="doc_text">
1076 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1077 several LLVM builds. Hence, it is possible to build LLVM for several different
1078 platforms or configurations using the same source tree.</p>
1080 <p>This is accomplished in the typical autoconf manner:</p>
1083 <li><p>Change directory to where the LLVM object files should live:</p>
1085 <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
1087 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1090 <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
1093 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1094 named after the build type:</p>
1101 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1103 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1111 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1113 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1121 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1123 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1129 <!-- ======================================================================= -->
1130 <div class="doc_subsection">
1131 <a name="optionalconfig">Optional Configuration Items</a>
1134 <div class="doc_text">
1137 If you're running on a Linux system that supports the "<a
1138 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">
1140 module, and you have root access on the system, you can set your system up to
1141 execute LLVM bitcode files directly. To do this, use commands like this (the
1142 first command may not be required if you are already using the module):</p>
1144 <div class="doc_code">
1146 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1147 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1148 $ chmod u+x hello.bc (if needed)
1154 This allows you to execute LLVM bitcode files directly. Thanks to Jack
1155 Cummings for pointing this out!
1161 <!-- *********************************************************************** -->
1162 <div class="doc_section">
1163 <a name="layout"><b>Program Layout</b></a>
1165 <!-- *********************************************************************** -->
1167 <div class="doc_text">
1169 <p>One useful source of information about the LLVM source base is the LLVM <a
1170 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1171 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1172 The following is a brief introduction to code layout:</p>
1176 <!-- ======================================================================= -->
1177 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1178 <div class="doc_text">
1179 <p>This directory contains some simple examples of how to use the LLVM IR and
1183 <!-- ======================================================================= -->
1184 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1185 <div class="doc_text">
1187 <p>This directory contains public header files exported from the LLVM
1188 library. The three main subdirectories of this directory are:</p>
1191 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1192 <dd>This directory contains all of the LLVM specific header files. This
1193 directory also has subdirectories for different portions of LLVM:
1194 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1197 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1198 <dd>This directory contains generic support libraries that are provided with
1199 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1200 and a Command Line option processing library store their header files here.
1203 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1204 <dd>This directory contains header files configured by the <tt>configure</tt>
1205 script. They wrap "standard" UNIX and C header files. Source code can
1206 include these header files which automatically take care of the conditional
1207 #includes that the <tt>configure</tt> script generates.</dd>
1211 <!-- ======================================================================= -->
1212 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1213 <div class="doc_text">
1215 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1216 almost all code exists in libraries, making it very easy to share code among the
1217 different <a href="#tools">tools</a>.</p>
1220 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1221 <dd> This directory holds the core LLVM source files that implement core
1222 classes like Instruction and BasicBlock.</dd>
1224 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1225 <dd>This directory holds the source code for the LLVM assembly language parser
1228 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1229 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1231 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1232 different program analyses, such as Dominator Information, Call Graphs,
1233 Induction Variables, Interval Identification, Natural Loop Identification,
1236 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1237 <dd> This directory contains the source code for the LLVM to LLVM program
1238 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1239 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1240 Elimination, and many others.</dd>
1242 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1243 <dd> This directory contains files that describe various target architectures
1244 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1245 directory holds the X86 machine description while
1246 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1248 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1249 <dd> This directory contains the major parts of the code generator: Instruction
1250 Selector, Instruction Scheduling, and Register Allocation.</dd>
1252 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1253 <dd> This directory contains the source level debugger library that makes
1254 it possible to instrument LLVM programs so that a debugger could identify
1255 source code locations at which the program is executing.</dd>
1257 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1258 <dd> This directory contains libraries for executing LLVM bitcode directly
1259 at runtime in both interpreted and JIT compiled fashions.</dd>
1261 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1262 <dd> This directory contains the source code that corresponds to the header
1263 files located in <tt>llvm/include/Support/</tt>.</dd>
1265 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1266 <dd>This directory contains the operating system abstraction layer that
1267 shields LLVM from platform-specific coding.</dd>
1272 <!-- ======================================================================= -->
1273 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1274 <div class="doc_text">
1275 <p>This directory contains projects that are not strictly part of LLVM but are
1276 shipped with LLVM. This is also the directory where you should create your own
1277 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1278 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1279 functional example of a compiler front end.</p>
1282 <!-- ======================================================================= -->
1283 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1284 <div class="doc_text">
1286 <p>This directory contains libraries which are compiled into LLVM bitcode and
1287 used when linking programs with the GCC front end. Most of these libraries are
1288 skeleton versions of real libraries; for example, libc is a stripped down
1289 version of glibc.</p>
1291 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1296 <!-- ======================================================================= -->
1297 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1298 <div class="doc_text">
1299 <p>This directory contains feature and regression tests and other basic sanity
1300 checks on the LLVM infrastructure. These are intended to run quickly and cover
1301 a lot of territory without being exhaustive.</p>
1304 <!-- ======================================================================= -->
1305 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1306 <div class="doc_text">
1307 <p>This is not a directory in the normal llvm module; it is a separate
1309 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1311 module contains a comprehensive correctness, performance, and benchmarking
1313 suite for LLVM. It is a separate Subversion module because not every LLVM
1315 interested in downloading or building such a comprehensive test suite. For
1316 further details on this test suite, please see the
1317 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1320 <!-- ======================================================================= -->
1321 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1322 <div class="doc_text">
1324 <p>The <b>tools</b> directory contains the executables built out of the
1325 libraries above, which form the main part of the user interface. You can
1326 always get help for a tool by typing <tt>tool_name --help</tt>. The
1327 following is a brief introduction to the most important tools. More detailed
1328 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1332 <dt><tt><b>bugpoint</b></tt></dt>
1333 <dd><tt>bugpoint</tt> is used to debug
1334 optimization passes or code generation backends by narrowing down the
1335 given test case to the minimum number of passes and/or instructions that
1336 still cause a problem, whether it is a crash or miscompilation. See <a
1337 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1338 on using <tt>bugpoint</tt>.</dd>
1340 <dt><tt><b>llvmc</b></tt></dt>
1341 <dd>The LLVM Compiler Driver. This program can
1342 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1343 pre-processing, translation, optimization, assembly, and linking of programs
1344 all from one command line. <tt>llvmc</tt> also takes care of processing the
1345 dependent libraries found in bitcode. This reduces the need to get the
1346 traditional <tt>-l<name></tt> options right on the command line. Please
1347 note that this tool, while functional, is still experimental and not feature
1350 <dt><tt><b>llvm-ar</b></tt></dt>
1351 <dd>The archiver produces an archive containing
1352 the given LLVM bitcode files, optionally with an index for faster
1355 <dt><tt><b>llvm-as</b></tt></dt>
1356 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1359 <dt><tt><b>llvm-dis</b></tt></dt>
1360 <dd>The disassembler transforms the LLVM bitcode to human readable
1363 <dt><tt><b>llvm-ld</b></tt></dt>
1364 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1365 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1366 optimizations and allows optimization modules to be loaded and run so that
1367 language specific optimizations can be applied at link time.</dd>
1369 <dt><tt><b>llvm-link</b></tt></dt>
1370 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1371 a single program.</dd>
1373 <dt><tt><b>lli</b></tt></dt>
1374 <dd><tt>lli</tt> is the LLVM interpreter, which
1375 can directly execute LLVM bitcode (although very slowly...). In addition
1376 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1377 specifying <tt>-trace</tt> on the command line). Finally, for
1378 architectures that support it (currently x86, Sparc, and PowerPC), by default,
1379 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1380 functionality was compiled in), and will execute the code <i>much</i>
1381 faster than the interpreter.</dd>
1383 <dt><tt><b>llc</b></tt></dt>
1384 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1385 translates LLVM bitcode to a native code assembly file or to C code (with
1386 the -march=c option).</dd>
1388 <dt><tt><b>llvm-gcc</b></tt></dt>
1389 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1390 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1391 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1392 usual machine code output. It works just like any other GCC compiler,
1393 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1394 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1395 separate Subversion module.</dd>
1397 <dt><tt><b>opt</b></tt></dt>
1398 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1399 transformations (which are specified on the command line), and then outputs
1400 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1401 get a list of the program transformations available in LLVM.<br/>
1402 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1403 LLVM bitcode file and print out the results. It is primarily useful for
1404 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1408 <!-- ======================================================================= -->
1409 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1410 <div class="doc_text">
1412 <p>This directory contains utilities for working with LLVM source code, and some
1413 of the utilities are actually required as part of the build process because they
1414 are code generators for parts of LLVM infrastructure.</p>
1417 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1418 that finds differences between code that LLC generates and code that LLI
1419 generates. This is a useful tool if you are debugging one of them,
1420 assuming that the other generates correct output. For the full user
1421 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1423 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1424 syntax-highlighting files which will work with Emacs and XEmacs editors,
1425 providing syntax highlighting support for LLVM assembly files and TableGen
1426 description files. For information on how to use the syntax files, consult
1427 the <tt>README</tt> file in that directory.<br><br>
1429 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1430 and outputs all non-generated source files, which is useful if one wishes
1431 to do a lot of development across directories and does not want to
1432 individually find each file. One way to use it is to run, for example:
1433 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1436 <dt><tt><b>llvmgrep</b></tt></dt>
1437 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1438 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1439 line. This is a very efficient way of searching the source base for a
1440 particular regular expression.</dd>
1442 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1443 files in the current directory and then compiles and links the tool that
1444 is the first argument. For example, assuming you are in the directory
1445 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1446 simply running <tt>makellvm llc</tt> will make a build of the current
1447 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1448 causing a re-linking of LLC.<br><br>
1450 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1451 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1452 cron script to generate nightly status reports of the functionality of
1453 tools, and the results can be seen by following the appropriate link on
1454 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1456 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1457 the tool used to generate register descriptions, instruction set
1458 descriptions, and even assemblers from common TableGen description
1461 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1462 syntax-highlighting files which will work with the VIM editor, providing
1463 syntax highlighting support for LLVM assembly files and TableGen
1464 description files. For information on how to use the syntax files, consult
1465 the <tt>README</tt> file in that directory.<br><br>
1471 <!-- ======================================================================= -->
1472 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1473 <div class="doc_text">
1474 <p>This directory contains build scripts and project files for use with
1475 Visual C++. This allows developers on Windows to build LLVM without the need
1476 for Cygwin. The contents of this directory should be considered experimental
1480 <!-- *********************************************************************** -->
1481 <div class="doc_section">
1482 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1484 <!-- *********************************************************************** -->
1486 <div class="doc_text">
1487 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1488 so we only include instructiosn for llvm-gcc4.
1491 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1492 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1493 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1494 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1495 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1499 <!-- ======================================================================= -->
1500 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1502 <div class="doc_text">
1505 <li>First, create a simple C file, name it 'hello.c':
1507 #include <stdio.h>
1509 printf("hello world\n");
1514 <li><p>Next, compile the C file into a native executable:</p>
1516 <p><tt>% llvm-gcc hello.c -o hello</tt></p>
1518 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1519 -c arguments work as usual (producing a native .s or .o file,
1522 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1523 <p><tt>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</tt></p>
1525 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1526 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1527 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1528 the bitcode file.</p>
1530 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1533 <li><p>Run the program in both forms. To run the program, use:</p>
1535 <p><tt>% ./hello</tt></p>
1539 <p><tt>% lli hello.bc</tt></p>
1541 <p>The second examples shows how to invoke the LLVM JIT, <a
1542 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1544 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1547 <p><tt>% llvm-dis < hello.bc | less</tt><br><br></li>
1549 <li><p>Compile the program to native assembly using the LLC code
1552 <p><tt>% llc hello.bc -o hello.s</tt></p>
1554 <li><p>Assemble the native assembly language file into a program:</p>
1556 <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1557 <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1559 <li><p>Execute the native code program:</p>
1561 <p><tt>% ./hello.native</tt></p>
1563 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1564 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1572 <!-- *********************************************************************** -->
1573 <div class="doc_section">
1574 <a name="problems">Common Problems</a>
1576 <!-- *********************************************************************** -->
1578 <div class="doc_text">
1580 <p>If you are having problems building or using LLVM, or if you have any other
1581 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1582 Asked Questions</a> page.</p>
1586 <!-- *********************************************************************** -->
1587 <div class="doc_section">
1588 <a name="links">Links</a>
1590 <!-- *********************************************************************** -->
1592 <div class="doc_text">
1594 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1595 some simple things... there are many more interesting and complicated things
1596 that you can do that aren't documented here (but we'll gladly accept a patch
1597 if you want to write something up!). For more information about LLVM, check
1601 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1602 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1603 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1604 that Uses LLVM</a></li>
1609 <!-- *********************************************************************** -->
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1618 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1619 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1620 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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