1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
6 <title>Getting Started with LLVM System</title>
7 <link rel="stylesheet" href="llvm.css" type="text/css">
11 <div class="doc_title">
12 Getting Started with the LLVM System
16 <li><a href="#overview">Overview</a>
17 <li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
18 <li><a href="#requirements">Requirements</a>
20 <li><a href="#hardware">Hardware</a>
21 <li><a href="#software">Software</a>
22 <li><a href="#brokengcc">Broken versions of GCC</a>
25 <li><a href="#starting">Getting Started with LLVM</a>
27 <li><a href="#terminology">Terminology and Notation</a>
28 <li><a href="#environment">Setting Up Your Environment</a>
29 <li><a href="#unpack">Unpacking the LLVM Archives</a>
30 <li><a href="#checkout">Checkout LLVM from CVS</a>
31 <li><a href="#installcf">Install the GCC Front End</a>
32 <li><a href="#config">Local LLVM Configuration</a>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
34 <li><a href="#objfiles">The Location of LLVM Object Files</a>
35 <li><a href="#optionalconfig">Optional Configuration Items</a>
38 <li><a href="#layout">Program layout</a>
40 <li><a href="#cvsdir"><tt>CVS</tt> directories</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>
54 <li><a href="#problems">Common Problems</a>
55 <li><a href="#links">Links</a>
58 <div class="doc_author">
60 <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
61 <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
62 <a href="http://misha.brukman.net">Misha Brukman</a>,
63 <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
64 <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
69 <!-- *********************************************************************** -->
70 <div class="doc_section">
71 <a name="overview"><b>Overview</b></a>
73 <!-- *********************************************************************** -->
75 <div class="doc_text">
77 <p>Welcome to LLVM! In order to get started, you first need to know some
78 basic information.</p>
80 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
81 contains all of the tools, libraries, and header files needed to use the low
82 level virtual machine. It contains an assembler, disassembler, bytecode
83 analyzer, and bytecode optimizer. It also contains a test suite that can be
84 used to test the LLVM tools and the GCC front end.</p>
86 <p>The second piece is the GCC front end. This component provides a version of
87 GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
88 end is a modified version of GCC 3.4 (we track the GCC 3.4 development). Once
89 compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
90 from the LLVM suite.</p>
93 There is a third, optional piece called llvm-test. It is a suite of programs
94 with a testing harness that can be used to further test LLVM's functionality
100 <!-- *********************************************************************** -->
101 <div class="doc_section">
102 <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
104 <!-- *********************************************************************** -->
106 <div class="doc_text">
108 <p>Here's the short story for getting up and running quickly with LLVM:</p>
111 <li>Read the documentation.</li>
112 <li>Read the documentation.</li>
113 <li>Remember that you were warned twice about reading the documentation.</li>
114 <li>Install the GCC front end if you intend to compile C or C++:
116 <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
117 <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
119 <li><tt>cd cfrontend/<i>platform</i><br>
120 ./fixheaders</tt></li>
121 <li>Add the cfrontend's "bin" directory to your PATH variable.</li>
124 <li>Get the LLVM Source Code
126 <li>With the distributed files (or use <a href="#checkout">CVS</a>):
128 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
129 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
134 <li><b>[Optional]</b> Get the Test Suite Source Code
136 <li>With the distributed files (or use <a href="#checkout">CVS</a>):
138 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
139 <li><tt>cd llvm/projects</tt>
140 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
146 <li>Configure the LLVM Build Environment
148 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
149 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
153 <li><tt>--prefix=<i>directory</i></tt>
154 <p>Specify for <i>directory</i> the full pathname of where you
155 want the LLVM tools and libraries to be installed (default
156 <tt>/usr/local</tt>).</p></li>
157 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
158 <p>Optionally, specify for <i>directory</i> the full pathname of the
159 C/C++ front end installation to use with this LLVM configuration. If
160 not specified, the PATH will be searched.</p></li>
161 <li><tt>--enable-spec2000=<i>directory</i></tt>
162 <p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
163 benchmarks should be available in
164 <tt><i>directory</i></tt>.</p></li>
168 <li>Build the LLVM Suite:
170 <li><tt>gmake -k |& tee gnumake.out
171 # this is csh or tcsh syntax</tt></li>
172 <li>If you get an "internal compiler error (ICE)" see <a href="#brokengcc">below</a>.</li>
177 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
178 detailed information on configuring and compiling LLVM. See <a
179 href="#environment">Setting Up Your Environment</a> for tips that simplify
180 working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
181 Layout</a> to learn about the layout of the source code tree.</p>
185 <!-- *********************************************************************** -->
186 <div class="doc_section">
187 <a name="requirements"><b>Requirements</b></a>
189 <!-- *********************************************************************** -->
191 <div class="doc_text">
193 <p>Before you begin to use the LLVM system, review the requirements given below.
194 This may save you some trouble by knowing ahead of time what hardware and
195 software you will need.</p>
199 <!-- ======================================================================= -->
200 <div class="doc_subsection">
201 <a name="hardware"><b>Hardware</b></a>
204 <div class="doc_text">
206 <p>LLVM is known to work on the following platforms:</p>
208 <table cellpadding="3">
216 <td>x86<sup><a href="#pf_1">1</a></sup></td>
221 <td>V9 (Ultrasparc)</td>
226 <td>x86<sup><a href="#pf_1">1</a></sup></td>
230 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
235 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
241 <td>Cygwin/Win32</td>
242 <td>x86<sup><a href="#pf_1">1</a></sup></td>
243 <td>GCC 3.4.X, binutils 2.15</td>
247 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a></sup></td>
248 <td>GCC 3.4.X, binutils 2.15</td>
252 <td>amd64<sup><a href="#pf_3">3</a></sup></td>
257 <p>LLVM has partial support for the following platforms:</p>
267 <td>x86<sup><a href="#pf_1">1</a></sup></td>
268 <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
270 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
275 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
281 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
286 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
287 <td>Itanium (IA-64)</td>
291 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
292 <td>Itanium (IA-64)</td>
299 <div class="doc_notes">
301 <li><a name="pf_1">Code generation supported for Pentium processors and
303 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
304 <li><a name="pf_3">No native code generation</a></li>
305 <li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
306 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
307 <li><a name="pf_6">The port is done using the MSYS shell.
308 <a href="http://www.mingw.org/MinGWiki/">Download</a> and install
309 bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
311 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
315 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
316 mode, depending on the system (it is so large because of all the debugging
317 information and the fact that the libraries are statically linked into multiple
318 tools). If you do not need many of the tools and you are space-conscious,
319 you can disable them individually in <tt>llvm/tools/Makefile</tt>. The Release
320 build requires considerably less space.</p>
322 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
323 guaranteed to do so. If compilation is successful, the LLVM utilities should be
324 able to assemble, disassemble, analyze, and optimize LLVM bytecode. Code
325 generation should work as well, although the generated native code may not work
326 on your platform.</p>
328 <p>The GCC front end is not very portable at the moment. If you want to get it
329 to work on another platform, you can download a copy of the source and <a
330 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
334 <!-- ======================================================================= -->
335 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
336 <div class="doc_text">
337 <p>Compiling LLVM requires that you have several software packages
338 installed. The table below lists those required packages. The Package column
339 is the usual name for the software package that LLVM depends on. The Version
340 column provides "known to work" versions of the package. The Notes column
341 describes how LLVM uses the package and provides other details.</p>
343 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
346 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
347 <td>3.79, 3.79.1</td>
348 <td>Makefile/build processor</td>
352 <td><a href="http://gcc.gnu.org">GCC</a></td>
354 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
358 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
360 <td>For building the CFE</td>
364 <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
366 <td>LEX compiler</td>
370 <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
371 <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
372 <td>YACC compiler</td>
376 <td><a href="https://www.cvshome.org/downloads.html">CVS</a></td>
378 <td>CVS access to LLVM<sup><a href="#sf2">2</a></sup></td>
382 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
384 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
388 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
390 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
394 <td><a href="http://expect.nist.gov/">expect</a></td>
396 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
400 <td><a href="http://www.perl.com/download.csp">perl</a></td>
402 <td>Nightly tester, utilities</td>
406 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
408 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
412 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
414 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
418 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
420 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
424 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
426 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
432 <div class="doc_notes">
434 <li><a name="sf3">Only the C and C++ languages are needed so there's no
435 need to build the other languages for LLVM's purposes.</a> See
436 <a href="#brokengcc">below</a> for specific version info.</li>
437 <li><a name="sf2">You only need CVS if you intend to build from the
438 latest LLVM sources. If you're working from a release distribution, you
439 don't need CVS.</a></li>
440 <li><a name="sf3">Only needed if you want to run the automated test
441 suite in the <tt>llvm/test</tt> directory.</a></li>
442 <li><a name="sf4">If you want to make changes to the configure scripts,
443 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
444 or higher). You will also need automake (1.9.2). We only use aclocal
445 from that package.</a></li>
449 <p>Additionally, your compilation host is expected to have the usual
450 plethora of Unix utilities. Specifically:</p>
452 <li><b>ar</b> - archive library builder</li>
453 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
454 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
455 <li><b>chmod</b> - change permissions on a file</li>
456 <li><b>cat</b> - output concatenation utility</li>
457 <li><b>cp</b> - copy files</li>
458 <li><b>date</b> - print the current date/time </li>
459 <li><b>echo</b> - print to standard output</li>
460 <li><b>egrep</b> - extended regular expression search utility</li>
461 <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
462 <li><b>find</b> - find files/dirs in a file system</li>
463 <li><b>grep</b> - regular expression search utility</li>
464 <li><b>gzip*</b> - gzip command for distribution generation</li>
465 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
466 <li><b>install</b> - install directories/files </li>
467 <li><b>mkdir</b> - create a directory</li>
468 <li><b>mv</b> - move (rename) files</li>
469 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
470 <li><b>rm</b> - remove (delete) files and directories</li>
471 <li><b>sed</b> - stream editor for transforming output</li>
472 <li><b>sh</b> - Bourne shell for make build scripts</li>
473 <li><b>tar</b> - tape archive for distribution generation</li>
474 <li><b>test</b> - test things in file system</li>
475 <li><b>unzip*</b> - unzip command for distribution checking</li>
476 <li><b>zip*</b> - zip command for distribution generation</li>
480 <!-- ======================================================================= -->
481 <div class="doc_subsection">
482 <a name="brokengcc">Broken versions of GCC</a>
485 <div class="doc_text">
487 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
488 bugs in the compiler. In particular, several versions of GCC crash when trying
489 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
490 successfully with them (however, see below). Other versions of GCC will
491 probably work as well. GCC versions listed
492 here are known to not work. If you are using one of these versions, please try
493 to upgrade your GCC to something more recent. If you run into a problem with a
494 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
495 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
496 of GCC you are using.
499 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
500 problems in the STL that effectively prevent it from compiling LLVM.
503 <p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
505 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
506 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
507 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
509 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
510 Cygwin does not work. Please <a href="CFEBuildInstrs.html#cygwin">upgrade
511 to a newer version</a> if possible.</p>
512 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
513 possibly others) does not compile LLVM correctly (it appears that exception
514 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
515 to a newer version of GCC.</p>
516 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
518 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
519 default with ENABLE_OPTIMIZED=1. To work around this, build with
520 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
525 <!-- *********************************************************************** -->
526 <div class="doc_section">
527 <a name="starting"><b>Getting Started with LLVM</b></a>
529 <!-- *********************************************************************** -->
531 <div class="doc_text">
533 <p>The remainder of this guide is meant to get you up and running with
534 LLVM and to give you some basic information about the LLVM environment.</p>
536 <p>The later sections of this guide describe the <a
537 href="#layout">general layout</a> of the the LLVM source tree, a <a
538 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
539 href="#links">links</a> to find more information about LLVM or to get
543 <!-- ======================================================================= -->
544 <div class="doc_subsection">
545 <a name="terminology">Terminology and Notation</a>
548 <div class="doc_text">
550 <p>Throughout this manual, the following names are used to denote paths
551 specific to the local system and working environment. <i>These are not
552 environment variables you need to set but just strings used in the rest
553 of this document below</i>. In any of the examples below, simply replace
554 each of these names with the appropriate pathname on your local system.
555 All these paths are absolute:</p>
560 This is the top level directory of the LLVM source tree.
565 This is the top level directory of the LLVM object tree (i.e. the
566 tree where object files and compiled programs will be placed. It
567 can be the same as SRC_ROOT).
572 This is where the LLVM GCC Front End is installed.
574 For the pre-built GCC front end binaries, the LLVMGCCDIR is
575 <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
580 <!-- ======================================================================= -->
581 <div class="doc_subsection">
582 <a name="environment">Setting Up Your Environment</a>
585 <div class="doc_text">
588 In order to compile and use LLVM, you may need to set some environment
592 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bytecode/libs</tt></dt>
593 <dd>[Optional] This environment variable helps LLVM linking tools find the
594 locations of your bytecode libraries. It is provided only as a
595 convenience since you can specify the paths using the -L options of the
596 tools and the C/C++ front-end will automatically use the bytecode files
598 <tt>lib</tt> directory.</dd>
603 <!-- ======================================================================= -->
604 <div class="doc_subsection">
605 <a name="unpack">Unpacking the LLVM Archives</a>
608 <div class="doc_text">
611 If you have the LLVM distribution, you will need to unpack it before you
612 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
613 suite and the LLVM GCC front end compiled for your platform. There is an
614 additional test suite that is optional. Each file is a TAR archive that is
615 compressed with the gzip program.
618 <p>The files are as follows, with <em>x.y</em> marking the version number:
620 <dt><tt>llvm-x.y.tar.gz</tt></dt>
621 <dd>Source release for the LLVM libraries and tools.<br/></dd>
623 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
624 <dd>Source release for the LLVM test suite.</dd>
626 <dt><tt>cfrontend-x.y.source.tar.gz</tt></dt>
627 <dd>Source release of the GCC front end.<br/></dd>
629 <dt><tt>cfrontend-x.y.i686-redhat-linux-gnu.tar.gz</tt></dt>
630 <dd>Binary release of the GCC front end for Linux/x86.<br/></dd>
632 <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
633 <dd>Source release of the llvm-gcc4 front end. See README.LLVM in the root
634 directory for build instructions.<br/></dd>
636 <dt><tt>llvm-gcc4-x.y.powerpc-apple-darwin8.6.0.tar.gz</tt></dt>
637 <dd>Binary release of the llvm-gcc4 front end for MacOS X/PowerPC.<br/></dd>
639 <dt><tt>llvm-gcc4-x.y.i686-apple-darwin8.6.1.tar.gz</tt></dt>
640 <dd>Binary release of the llvm-gcc4 front end for MacOS X/X86.<br/></dd>
645 <!-- ======================================================================= -->
646 <div class="doc_subsection">
647 <a name="checkout">Checkout LLVM from CVS</a>
650 <div class="doc_text">
652 <p>If you have access to our CVS repository, you can get a fresh copy of
653 the entire source code. All you need to do is check it out from CVS as
657 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
658 <li><tt>cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt>
659 <li>Hit the return key when prompted for the password.
660 <li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co
664 <p>This will create an '<tt>llvm</tt>' directory in the current
665 directory and fully populate it with the LLVM source code, Makefiles,
666 test directories, and local copies of documentation files.</p>
668 <p>If you want to get a specific release (as opposed to the most recent
669 revision), you can specify a label. The following releases have the following
673 <li>Release 1.7: <b>RELEASE_17</b></li>
674 <li>Release 1.6: <b>RELEASE_16</b></li>
675 <li>Release 1.5: <b>RELEASE_15</b></li>
676 <li>Release 1.4: <b>RELEASE_14</b></li>
677 <li>Release 1.3: <b>RELEASE_13</b></li>
678 <li>Release 1.2: <b>RELEASE_12</b></li>
679 <li>Release 1.1: <b>RELEASE_11</b></li>
680 <li>Release 1.0: <b>RELEASE_1</b></li>
683 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
684 you get it from the CVS repository:</p>
687 cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-test
689 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
690 configured by the LLVM configure script as well as automatically updated when
691 you run <tt>cvs update</tt>.</p>
693 <p>If you would like to get the GCC 3.4 front end source code, you can also get it from the CVS repository:</p>
696 cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-gcc
699 <p>Please note that you must follow <a href="CFEBuildInstrs.html">these
700 instructions</a> to successfully build the LLVM GCC front-end.</p>
704 <!-- ======================================================================= -->
705 <div class="doc_subsection">
706 <a name="installcf">Install the GCC Front End</a>
709 <div class="doc_text">
711 <p>Before configuring and compiling the LLVM suite, you need to extract the LLVM
712 GCC front end from the binary distribution. It is used for building the
713 bytecode libraries later used by the GCC front end for linking programs, and its
714 location must be specified when the LLVM suite is configured.</p>
716 <p>To install the GCC front end, do the following:</p>
719 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
720 <li><tt>gunzip --stdout cfrontend-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
724 <p>Next, you will need to fix your system header files:</p>
726 <p><tt>cd cfrontend/<i>platform</i><br>
727 ./fixheaders</tt></p>
729 <p>The binary versions of the GCC front end may not suit all of your needs. For
730 example, the binary distribution may include an old version of a system header
731 file, not "fix" a header file that needs to be fixed for GCC, or it may be
732 linked with libraries not available on your system.</p>
734 <p>In cases like these, you may want to try <a
735 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
736 not for the faint of heart, so be forewarned.</p>
740 <!-- ======================================================================= -->
741 <div class="doc_subsection">
742 <a name="config">Local LLVM Configuration</a>
745 <div class="doc_text">
747 <p>Once checked out from the CVS repository, the LLVM suite source code must be
748 configured via the <tt>configure</tt> script. This script sets variables in the
749 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
750 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
751 the Makefiles needed to begin building LLVM.</p>
753 <p>The following environment variables are used by the <tt>configure</tt>
754 script to configure the build system:</p>
757 <tr><th>Variable</th><th>Purpose</th></tr>
760 <td>Tells <tt>configure</tt> which C compiler to use. By default,
761 <tt>configure</tt> will look for the first GCC C compiler in
762 <tt>PATH</tt>. Use this variable to override
763 <tt>configure</tt>'s default behavior.</td>
767 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
768 <tt>configure</tt> will look for the first GCC C++ compiler in
769 <tt>PATH</tt>. Use this variable to override
770 <tt>configure</tt>'s default behavior.</td>
774 <p>The following options can be used to set or enable LLVM specific options:</p>
777 <dt><i>--with-llvmgccdir</i></dt>
778 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
779 The value of this option should specify the full pathname of the C/C++ Front
780 End to be used. If this option is not provided, the PATH will be searched for
781 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
782 be inferred from the path found. If the option is not given, and no llvm-gcc
783 can be found in the path then a warning will be produced by
784 <tt>configure</tt> indicating this situation. LLVM may still be built with
785 the <tt>tools-only</tt> target but attempting to build the runtime libraries
786 will fail as these libraries require llvm-gcc and llvm-g++. See
787 <a href="#installcf">Install the GCC Front End</a> for details on installing
788 the C/C++ Front End. See
789 <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
790 for details on building the C/C++ Front End.</dd>
791 <dt><i>--with-tclinclude</i></dt>
792 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
793 found. Use this if you have multiple tcl installations on your machine and you
794 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
795 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
796 option, the LLVM configure script will search for the tcl 8.4 and 8.3
800 <dt><i>--enable-optimized</i></dt>
802 Enables optimized compilation by default (debugging symbols are removed
803 and GCC optimization flags are enabled). The default is to use an
804 unoptimized build (also known as a debug build).
807 <dt><i>--enable-debug-runtime</i></dt>
809 Enables debug symbols in the runtime libraries. The default is to strip
810 debug symbols from the runtime libraries.
812 <dt><i>--enable-jit</i></dt>
814 Compile the Just In Time (JIT) compiler functionality. This is not
816 on all platforms. The default is dependent on platform, so it is best
817 to explicitly enable it if you want it.
820 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
821 <dd>Controls which targets will be built and linked into llc. The default
822 value for <tt>target_options</tt> is "all" which builds and links all
823 available targets. The value "host-only" can be specified to build only a
824 native compiler (no cross-compiler targets available). The "native" target is
825 selected as the target of the build host. You can also specify a comma
826 separated list of target names that you want available in llc. The target
827 names use all lower case. The current set of targets is: <br/>
828 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
830 <dt><i>--enable-doxygen</i></dt>
831 <dd>Look for the doxygen program and enable construction of doxygen based
832 documentation from the source code. This is disabled by default because
833 generating the documentation can take a long time and producess 100s of
834 megabytes of output.</dd>
837 <p>To configure LLVM, follow these steps:</p>
840 <li>Change directory into the object root directory:
842 <tt>cd <i>OBJ_ROOT</i></tt>
845 <li>Run the <tt>configure</tt> script located in the LLVM source tree:
847 <tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
853 <!-- ======================================================================= -->
854 <div class="doc_subsection">
855 <a name="compile">Compiling the LLVM Suite Source Code</a>
858 <div class="doc_text">
860 <p>Once you have configured LLVM, you can build it. There are three types of
866 These builds are the default when one types <tt>gmake</tt> (unless the
867 <tt>--enable-optimized</tt> option was used during configuration). The
868 build system will compile the tools and libraries with debugging
872 <dt>Release (Optimized) Builds
874 These builds are enabled with the <tt>--enable-optimized</tt> option to
875 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
876 <tt>gmake</tt> command line. For these builds, the build system will
877 compile the tools and libraries with GCC optimizations enabled and strip
878 debugging information from the libraries and executables it generates.
883 These builds are for use with profiling. They compile profiling
884 information into the code for use with programs like <tt>gprof</tt>.
885 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
886 on the <tt>gmake</tt> command line.
889 <p>Once you have LLVM configured, you can build it by entering the
890 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
892 <p><tt>gmake</tt></p>
894 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
895 are using a version of GCC that is known not to compile LLVM.</p>
898 If you have multiple processors in your machine, you may wish to use some of
899 the parallel build options provided by GNU Make. For example, you could use the
902 <p><tt>gmake -j2</tt></p>
904 <p>There are several special targets which are useful when working with the LLVM
908 <dt><tt>gmake clean</tt>
910 Removes all files generated by the build. This includes object files,
911 generated C/C++ files, libraries, and executables.
914 <dt><tt>gmake dist-clean</tt>
916 Removes everything that <tt>gmake clean</tt> does, but also removes files
917 generated by <tt>configure</tt>. It attempts to return the source tree to the
918 original state in which it was shipped.
921 <dt><tt>gmake install</tt>
923 Installs LLVM header files, libraries, tools, and documentation in a
925 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
926 defaults to <tt>/usr/local</tt>.
929 <dt><tt>gmake -C runtime install-bytecode</tt>
931 Assuming you built LLVM into $OBJDIR, when this command is run, it will
932 install bytecode libraries into the GCC front end's bytecode library
933 directory. If you need to update your bytecode libraries,
934 this is the target to use once you've built them.
938 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
939 details on these <tt>make</tt> targets and descriptions of other targets
942 <p>It is also possible to override default values from <tt>configure</tt> by
943 declaring variables on the command line. The following are some examples:</p>
946 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
948 Perform a Release (Optimized) build.
951 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
953 Perform a Release (Optimized) build without assertions enabled.
956 <dt><tt>gmake ENABLE_PROFILING=1</tt>
958 Perform a Profiling build.
961 <dt><tt>gmake VERBOSE=1</tt>
963 Print what <tt>gmake</tt> is doing on standard output.
966 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
967 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
968 the standard output. This also implies <tt>VERBOSE=1</tt>.
972 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
973 it and any subdirectories that it contains. Entering any directory inside the
974 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
975 that directory that is out of date.</p>
979 <!-- ======================================================================= -->
980 <div class="doc_subsection">
981 <a name="objfiles">The Location of LLVM Object Files</a>
984 <div class="doc_text">
986 <p>The LLVM build system is capable of sharing a single LLVM source tree among
987 several LLVM builds. Hence, it is possible to build LLVM for several different
988 platforms or configurations using the same source tree.</p>
990 <p>This is accomplished in the typical autoconf manner:</p>
993 <li><p>Change directory to where the LLVM object files should live:</p>
995 <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
997 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1000 <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
1003 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1004 named after the build type:</p>
1011 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1013 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1021 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1023 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1031 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1033 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1039 <!-- ======================================================================= -->
1040 <div class="doc_subsection">
1041 <a name="optionalconfig">Optional Configuration Items</a>
1044 <div class="doc_text">
1047 If you're running on a Linux system that supports the "<a
1048 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">
1050 module, and you have root access on the system, you can set your system up to
1051 execute LLVM bytecode files directly. To do this, use commands like this (the
1052 first command may not be required if you are already using the module):</p>
1054 <div class="doc_code">
1056 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1057 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1058 $ chmod u+x hello.bc (if needed)
1064 This allows you to execute LLVM bytecode files directly. Thanks to Jack
1065 Cummings for pointing this out!
1071 <!-- *********************************************************************** -->
1072 <div class="doc_section">
1073 <a name="layout"><b>Program Layout</b></a>
1075 <!-- *********************************************************************** -->
1077 <div class="doc_text">
1079 <p>One useful source of information about the LLVM source base is the LLVM <a
1080 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1081 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1082 The following is a brief introduction to code layout:</p>
1086 <!-- ======================================================================= -->
1087 <div class="doc_subsection"><a name="cvsdir"><tt>CVS</tt> directories</a></div>
1088 <div class="doc_text">
1089 <p>Every directory checked out of CVS will contain a <tt>CVS</tt> directory; for
1090 the most part these can just be ignored.</p>
1093 <!-- ======================================================================= -->
1094 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1095 <div class="doc_text">
1096 <p>This directory contains some simple examples of how to use the LLVM IR and
1100 <!-- ======================================================================= -->
1101 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1102 <div class="doc_text">
1104 <p>This directory contains public header files exported from the LLVM
1105 library. The three main subdirectories of this directory are:</p>
1108 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1109 <dd>This directory contains all of the LLVM specific header files. This
1110 directory also has subdirectories for different portions of LLVM:
1111 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1114 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1115 <dd>This directory contains generic support libraries that are provided with
1116 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1117 and a Command Line option processing library store their header files here.
1120 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1121 <dd>This directory contains header files configured by the <tt>configure</tt>
1122 script. They wrap "standard" UNIX and C header files. Source code can
1123 include these header files which automatically take care of the conditional
1124 #includes that the <tt>configure</tt> script generates.</dd>
1128 <!-- ======================================================================= -->
1129 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1130 <div class="doc_text">
1132 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1133 almost all code exists in libraries, making it very easy to share code among the
1134 different <a href="#tools">tools</a>.</p>
1137 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1138 <dd> This directory holds the core LLVM source files that implement core
1139 classes like Instruction and BasicBlock.</dd>
1141 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1142 <dd>This directory holds the source code for the LLVM assembly language parser
1145 <dt><tt><b>llvm/lib/ByteCode/</b></tt></dt>
1146 <dd>This directory holds code for reading and write LLVM bytecode.</dd>
1148 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1149 different program analyses, such as Dominator Information, Call Graphs,
1150 Induction Variables, Interval Identification, Natural Loop Identification,
1153 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1154 <dd> This directory contains the source code for the LLVM to LLVM program
1155 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1156 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1157 Elimination, and many others.</dd>
1159 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1160 <dd> This directory contains files that describe various target architectures
1161 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1162 directory holds the X86 machine description while
1163 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1165 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1166 <dd> This directory contains the major parts of the code generator: Instruction
1167 Selector, Instruction Scheduling, and Register Allocation.</dd>
1169 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1170 <dd> This directory contains the source level debugger library that makes
1171 it possible to instrument LLVM programs so that a debugger could identify
1172 source code locations at which the program is executing.</dd>
1174 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1175 <dd> This directory contains libraries for executing LLVM bytecode directly
1176 at runtime in both interpreted and JIT compiled fashions.</dd>
1178 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1179 <dd> This directory contains the source code that corresponds to the header
1180 files located in <tt>llvm/include/Support/</tt>.</dd>
1182 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1183 <dd>This directory contains the operating system abstraction layer that
1184 shields LLVM from platform-specific coding.</dd>
1189 <!-- ======================================================================= -->
1190 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1191 <div class="doc_text">
1192 <p>This directory contains projects that are not strictly part of LLVM but are
1193 shipped with LLVM. This is also the directory where you should create your own
1194 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1195 to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1196 functional example of a compiler front end.</p>
1199 <!-- ======================================================================= -->
1200 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1201 <div class="doc_text">
1203 <p>This directory contains libraries which are compiled into LLVM bytecode and
1204 used when linking programs with the GCC front end. Most of these libraries are
1205 skeleton versions of real libraries; for example, libc is a stripped down
1206 version of glibc.</p>
1208 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1213 <!-- ======================================================================= -->
1214 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1215 <div class="doc_text">
1216 <p>This directory contains feature and regression tests and other basic sanity
1217 checks on the LLVM infrastructure. These are intended to run quickly and cover
1218 a lot of territory without being exhaustive.</p>
1221 <!-- ======================================================================= -->
1222 <div class="doc_subsection"><a name="llvmtest"><tt>llvm-test</tt></a></div>
1223 <div class="doc_text">
1224 <p>This is not a directory in the normal llvm module; it is a separate CVS
1225 module that must be checked out (usually to <tt>projects/llvm-test</tt>). This
1226 module contains a comprehensive correctness, performance, and benchmarking
1228 suite for LLVM. It is a separate CVS module because not every LLVM user is
1229 interested in downloading or building such a comprehensive test suite. For
1230 further details on this test suite, please see the
1231 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1234 <!-- ======================================================================= -->
1235 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1236 <div class="doc_text">
1238 <p>The <b>tools</b> directory contains the executables built out of the
1239 libraries above, which form the main part of the user interface. You can
1240 always get help for a tool by typing <tt>tool_name --help</tt>. The
1241 following is a brief introduction to the most important tools. More detailed
1242 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1245 <dt><tt><b>analyze</b></tt></dt>
1246 <dd><tt>analyze</tt> is used to run a specific
1247 analysis on an input LLVM bytecode file and print out the results. It is
1248 primarily useful for debugging analyses, or familiarizing yourself with
1249 what an analysis does.</dd>
1251 <dt><tt><b>bugpoint</b></tt></dt>
1252 <dd><tt>bugpoint</tt> is used to debug
1253 optimization passes or code generation backends by narrowing down the
1254 given test case to the minimum number of passes and/or instructions that
1255 still cause a problem, whether it is a crash or miscompilation. See <a
1256 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1257 on using <tt>bugpoint</tt>.</dd>
1259 <dt><tt><b>llvmc</b></tt></dt>
1260 <dd>The LLVM Compiler Driver. This program can
1261 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1262 pre-processing, translation, optimization, assembly, and linking of programs
1263 all from one command line. <tt>llvmc</tt> also takes care of processing the
1264 dependent libraries found in bytecode. This reduces the need to get the
1265 traditional <tt>-l<name></tt> options right on the command line. Please
1266 note that this tool, while functional, is still experimental and not feature
1269 <dt><tt><b>llvm-ar</b></tt></dt>
1270 <dd>The archiver produces an archive containing
1271 the given LLVM bytecode files, optionally with an index for faster
1274 <dt><tt><b>llvm-as</b></tt></dt>
1275 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1278 <dt><tt><b>llvm-dis</b></tt></dt>
1279 <dd>The disassembler transforms the LLVM bytecode to human readable
1282 <dt><tt><b>llvm-ld</b></tt></dt>
1283 <dd><tt>llvm-ld</tt> is very similar to gccld and provides a general purpose
1284 and extensible linker for LLVM. This is the linker invoked by <tt>llvmc</tt>.
1285 It allows optimization modules to be loaded so that language specific
1286 optimizations can be applied at link time. This tool is considered
1289 <dt><tt><b>llvm-link</b></tt></dt>
1290 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1291 a single program.</dd>
1293 <dt><tt><b>lli</b></tt></dt>
1294 <dd><tt>lli</tt> is the LLVM interpreter, which
1295 can directly execute LLVM bytecode (although very slowly...). In addition
1296 to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1297 specifying <tt>-trace</tt> on the command line). Finally, for
1298 architectures that support it (currently x86, Sparc, and PowerPC), by default,
1299 <tt>lli</tt> will function as a Just-In-Time compiler (if the
1300 functionality was compiled in), and will execute the code <i>much</i>
1301 faster than the interpreter.</dd>
1303 <dt><tt><b>llc</b></tt></dt>
1304 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1305 translates LLVM bytecode to a native code assembly file or to C code (with
1306 the -march=c option).</dd>
1308 <dt><tt><b>llvm-gcc</b></tt></dt>
1309 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend
1310 that has been retargeted to emit LLVM code as the machine code output. It
1311 works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
1312 -o</tt> options that are typically used. The source code for the
1313 <tt>llvm-gcc</tt> tool is available as a separate CVS module.
1316 <dt><tt><b>gccas</b></tt></dt>
1317 <dd>This tool is invoked by the <tt>llvm-gcc</tt> frontend as the
1318 "assembler" part of the compiler. This tool actually assembles LLVM
1319 assembly to LLVM bytecode, performs a variety of optimizations, and
1320 outputs LLVM bytecode. Thus when you invoke
1321 <tt>llvm-gcc -c x.c -o x.o</tt>, you are causing <tt>gccas</tt> to be
1322 run, which writes the <tt>x.o</tt> file (which is an LLVM bytecode file
1323 that can be disassembled or manipulated just like any other bytecode
1324 file). The command line interface to <tt>gccas</tt> is designed to be
1325 as close as possible to the <b>system</b> `<tt>as</tt>' utility so that
1326 the gcc frontend itself did not have to be modified to interface to
1327 a "weird" assembler.</dd>
1329 <dt><tt><b>gccld</b></tt></dt>
1330 <dd><tt>gccld</tt> links together several LLVM bytecode files into one
1331 bytecode file and does some optimization. It is the linker invoked by
1332 the GCC frontend when multiple .o files need to be linked together.
1333 Like <tt>gccas</tt>, the command line interface of <tt>gccld</tt> is
1334 designed to match the system linker, to aid interfacing with the GCC
1340 <dt><tt><b>opt</b></tt></dt>
1341 <dd><tt>opt</tt> reads LLVM bytecode, applies a
1342 series of LLVM to LLVM transformations (which are specified on the command
1343 line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
1344 command is a good way to get a list of the program transformations
1345 available in LLVM.</dd>
1349 <!-- ======================================================================= -->
1350 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1351 <div class="doc_text">
1353 <p>This directory contains utilities for working with LLVM source code, and some
1354 of the utilities are actually required as part of the build process because they
1355 are code generators for parts of LLVM infrastructure.</p>
1358 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1359 that finds differences between code that LLC generates and code that LLI
1360 generates. This is a useful tool if you are debugging one of them,
1361 assuming that the other generates correct output. For the full user
1362 manual, run <tt>`perldoc codegen-diff'</tt>.<p>
1364 <dt><tt><b>cvsupdate</b></tt> <dd><tt>cvsupdate</tt> is a script that will
1365 update your CVS tree, but produce a much cleaner and more organized output
1366 than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group
1367 together all the new and updated files and modified files in separate
1368 sections, so you can see at a glance what has changed. If you are at the
1369 top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the
1370 preferred way of updating the tree.<p>
1372 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1373 syntax-highlighting files which will work with Emacs and XEmacs editors,
1374 providing syntax highlighting support for LLVM assembly files and TableGen
1375 description files. For information on how to use the syntax files, consult
1376 the <tt>README</tt> file in that directory.<p>
1378 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1379 and outputs all non-generated source files, which is useful if one wishes
1380 to do a lot of development across directories and does not want to
1381 individually find each file. One way to use it is to run, for example:
1382 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1385 <dt><tt><b>llvmgrep</b></tt></dt>
1386 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1387 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1388 line. This is a very efficient way of searching the source base for a
1389 particular regular expression.</dd>
1391 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1392 files in the current directory and then compiles and links the tool that
1393 is the first argument. For example, assuming you are in the directory
1394 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1395 simply running <tt>makellvm llc</tt> will make a build of the current
1396 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1397 causing a re-linking of LLC.<p>
1399 <dt><tt><b>NightlyTest.pl</b></tt> and
1400 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1401 cron script to generate nightly status reports of the functionality of
1402 tools, and the results can be seen by following the appropriate link on
1403 the <a href="http://llvm.org/">LLVM homepage</a>.<p>
1405 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1406 the tool used to generate register descriptions, instruction set
1407 descriptions, and even assemblers from common TableGen description
1410 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1411 syntax-highlighting files which will work with the VIM editor, providing
1412 syntax highlighting support for LLVM assembly files and TableGen
1413 description files. For information on how to use the syntax files, consult
1414 the <tt>README</tt> file in that directory.<p>
1420 <!-- ======================================================================= -->
1421 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1422 <div class="doc_text">
1423 <p>This directory contains build scripts and project files for use with
1424 Visual C++. This allows developers on Windows to build LLVM without the need
1425 for Cygwin. The contents of this directory should be considered experimental
1429 <!-- *********************************************************************** -->
1430 <div class="doc_section">
1431 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1433 <!-- *********************************************************************** -->
1435 <div class="doc_text">
1438 <li>First, create a simple C file, name it 'hello.c':
1440 #include <stdio.h>
1442 printf("hello world\n");
1447 <li><p>Next, compile the C file into a LLVM bytecode file:</p>
1448 <p><tt>% llvm-gcc hello.c -o hello</tt></p>
1450 <p>Note that you should have already built the tools and they have to be
1451 in your path, at least <tt>gccas</tt> and <tt>gccld</tt>.</p>
1453 <p>This will create two result files: <tt>hello</tt> and
1454 <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
1455 corresponds the the compiled program and the library facilities that it
1456 required. <tt>hello</tt> is a simple shell script that runs the bytecode
1457 file with <tt>lli</tt>, making the result directly executable. Note that
1458 all LLVM optimizations are enabled by default, so there is no need for a
1459 "-O3" switch.</p></li>
1461 <li><p>Run the program. To make sure the program ran, execute one of the
1462 following commands:</p>
1464 <p><tt>% ./hello</tt></p>
1468 <p><tt>% lli hello.bc</tt></p></li>
1470 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1473 <p><tt>% llvm-dis < hello.bc | less</tt><p></li>
1475 <li><p>Compile the program to native assembly using the LLC code
1478 <p><tt>% llc hello.bc -o hello.s</tt></p>
1480 <li><p>Assemble the native assembly language file into a program:</p>
1482 <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1483 <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1485 <li><p>Execute the native code program:</p>
1487 <p><tt>% ./hello.native</tt></p></li>
1493 <!-- *********************************************************************** -->
1494 <div class="doc_section">
1495 <a name="problems">Common Problems</a>
1497 <!-- *********************************************************************** -->
1499 <div class="doc_text">
1501 <p>If you are having problems building or using LLVM, or if you have any other
1502 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1503 Asked Questions</a> page.</p>
1507 <!-- *********************************************************************** -->
1508 <div class="doc_section">
1509 <a name="links">Links</a>
1511 <!-- *********************************************************************** -->
1513 <div class="doc_text">
1515 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1516 some simple things... there are many more interesting and complicated things
1517 that you can do that aren't documented here (but we'll gladly accept a patch
1518 if you want to write something up!). For more information about LLVM, check
1522 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1523 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1524 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1525 that Uses LLVM</a></li>
1530 <!-- *********************************************************************** -->
1534 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1535 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
1536 <a href="http://validator.w3.org/check/referer"><img
1537 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
1539 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1540 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1541 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1542 Last modified: $Date$