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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></li>
21 <li><a href="#software">Software</a></li>
22 <li><a href="#brokengcc">Broken versions of GCC and other tools</a></li>
25 <li><a href="#starting">Getting Started with LLVM</a>
27 <li><a href="#terminology">Terminology and Notation</a></li>
28 <li><a href="#environment">Setting Up Your Environment</a></li>
29 <li><a href="#unpack">Unpacking the LLVM Archives</a></li>
30 <li><a href="#checkout">Checkout LLVM from Subversion</a></li>
31 <li><a href="#installcf">Install the GCC Front End</a></li>
32 <li><a href="#config">Local LLVM Configuration</a></li>
33 <li><a href="#compile">Compiling the LLVM Suite Source Code</a></li>
34 <li><a href="#cross-compile">Cross-Compiling LLVM</a></li>
35 <li><a href="#objfiles">The Location of LLVM Object Files</a></li>
36 <li><a href="#optionalconfig">Optional Configuration Items</a></li>
39 <li><a href="#layout">Program layout</a>
41 <li><a href="#examples"><tt>llvm/examples</tt></a></li>
42 <li><a href="#include"><tt>llvm/include</tt></a></li>
43 <li><a href="#lib"><tt>llvm/lib</tt></a></li>
44 <li><a href="#projects"><tt>llvm/projects</tt></a></li>
45 <li><a href="#runtime"><tt>llvm/runtime</tt></a></li>
46 <li><a href="#test"><tt>llvm/test</tt></a></li>
47 <li><a href="#llvmtest"><tt>llvm-test</tt></a></li>
48 <li><a href="#tools"><tt>llvm/tools</tt></a></li>
49 <li><a href="#utils"><tt>llvm/utils</tt></a></li>
50 <li><a href="#win32"><tt>llvm/win32</tt></a></li>
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 llvm-gcc-4.2 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-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt>
122 <li>Note: If the binary extension is ".bz" use bunzip2 instead of gunzip.</li>
123 <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
126 <li>Get the LLVM Source Code
128 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
130 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
131 <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
136 <li><b>[Optional]</b> Get the Test Suite Source Code
138 <li>With the distributed files (or use <a href="#checkout">SVN</a>):
140 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
141 <li><tt>cd llvm/projects</tt>
142 <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
148 <li>Configure the LLVM Build Environment
150 <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
151 <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
155 <li><tt>--prefix=<i>directory</i></tt>
156 <p>Specify for <i>directory</i> the full pathname of where you
157 want the LLVM tools and libraries to be installed (default
158 <tt>/usr/local</tt>).</p></li>
159 <li><tt>--with-llvmgccdir=<i>directory</i></tt>
160 <p>Optionally, specify for <i>directory</i> the full pathname of the
161 C/C++ front end installation to use with this LLVM configuration. If
162 not specified, the PATH will be searched. This is only needed if you
163 want to run the testsuite or do some special kinds of LLVM builds.</p></li>
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>x86<sup><a href="#pf_1">1</a></sup></td>
235 <td>V9 (Ultrasparc)</td>
240 <td>x86<sup><a href="#pf_1">1</a></sup></td>
244 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
249 <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
254 <td>Cygwin/Win32</td>
255 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
256 <td>GCC 3.4.X, binutils 2.15</td>
260 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,
261 <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td>
262 <td>GCC 3.4.X, binutils 2.15</td>
266 <p>LLVM has partial support for the following platforms:</p>
268 <table summary="LLVM partial platform support">
276 <td>x86<sup><a href="#pf_1">1</a></sup></td>
277 <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
279 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
284 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
290 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
295 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
296 <td>Itanium (IA-64)</td>
300 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
301 <td>Itanium (IA-64)</td>
308 <div class="doc_notes">
310 <li><a name="pf_1">Code generation supported for Pentium processors and
312 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
313 <li><a name="pf_3">No native code generation</a></li>
314 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
315 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
316 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
317 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
318 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
319 preventing LLVM from building correctly. Several workarounds have been
320 introduced into LLVM build system, but the bug can occur anytime in the
321 future. We highly recommend that you rebuild your current binutils with the
322 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
323 Binutils bugzilla</a>, if it wasn't already applied.</li>
324 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
325 internal LLVM assert messages when compiled for Release at optimization
326 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
327 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
328 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
329 <li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS
330 version of the perl package, and be sure it appears in your path
331 before any Windows-based versions such as Strawberry Perl and
332 ActivePerl, as these have Windows-specifics that will cause the
333 build to fail.</a></li>
337 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
338 mode, depending on the system (it is so large because of all the debugging
339 information and the fact that the libraries are statically linked into multiple
340 tools). If you do not need many of the tools and you are space-conscious, you
341 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
342 requires considerably less space.</p>
344 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
345 guaranteed to do so. If compilation is successful, the LLVM utilities should be
346 able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
347 generation should work as well, although the generated native code may not work
348 on your platform.</p>
350 <p>The GCC front end is not very portable at the moment. If you want to get it
351 to work on another platform, you can download a copy of the source and <a
352 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
356 <!-- ======================================================================= -->
357 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
358 <div class="doc_text">
359 <p>Compiling LLVM requires that you have several software packages
360 installed. The table below lists those required packages. The Package column
361 is the usual name for the software package that LLVM depends on. The Version
362 column provides "known to work" versions of the package. The Notes column
363 describes how LLVM uses the package and provides other details.</p>
364 <table summary="Packages required to compile LLVM">
365 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
368 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
369 <td>3.79, 3.79.1</td>
370 <td>Makefile/build processor</td>
374 <td><a href="http://gcc.gnu.org">GCC</a></td>
376 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
380 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
382 <td>For building the CFE</td>
386 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
388 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
392 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
394 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
398 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
400 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
404 <td><a href="http://expect.nist.gov/">expect</a></td>
406 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
410 <td><a href="http://www.perl.com/download.csp">perl</a></td>
412 <td>Nightly tester, utilities</td>
416 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
418 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
422 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
424 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
428 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
430 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
434 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
436 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
442 <div class="doc_notes">
444 <li><a name="sf1">Only the C and C++ languages are needed so there's no
445 need to build the other languages for LLVM's purposes.</a> See
446 <a href="#brokengcc">below</a> for specific version info.</li>
447 <li><a name="sf2">You only need Subversion if you intend to build from the
448 latest LLVM sources. If you're working from a release distribution, you
449 don't need Subversion.</a></li>
450 <li><a name="sf3">Only needed if you want to run the automated test
451 suite in the <tt>llvm/test</tt> directory.</a></li>
452 <li><a name="sf4">If you want to make changes to the configure scripts,
453 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
454 or higher). You will also need automake (1.9.2). We only use aclocal
455 from that package.</a></li>
459 <p>Additionally, your compilation host is expected to have the usual
460 plethora of Unix utilities. Specifically:</p>
462 <li><b>ar</b> - archive library builder</li>
463 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
464 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
465 <li><b>chmod</b> - change permissions on a file</li>
466 <li><b>cat</b> - output concatenation utility</li>
467 <li><b>cp</b> - copy files</li>
468 <li><b>date</b> - print the current date/time </li>
469 <li><b>echo</b> - print to standard output</li>
470 <li><b>egrep</b> - extended regular expression search utility</li>
471 <li><b>find</b> - find files/dirs in a file system</li>
472 <li><b>grep</b> - regular expression search utility</li>
473 <li><b>gzip*</b> - gzip command for distribution generation</li>
474 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
475 <li><b>install</b> - install directories/files </li>
476 <li><b>mkdir</b> - create a directory</li>
477 <li><b>mv</b> - move (rename) files</li>
478 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
479 <li><b>rm</b> - remove (delete) files and directories</li>
480 <li><b>sed</b> - stream editor for transforming output</li>
481 <li><b>sh</b> - Bourne shell for make build scripts</li>
482 <li><b>tar</b> - tape archive for distribution generation</li>
483 <li><b>test</b> - test things in file system</li>
484 <li><b>unzip*</b> - unzip command for distribution checking</li>
485 <li><b>zip*</b> - zip command for distribution generation</li>
489 <!-- ======================================================================= -->
490 <div class="doc_subsection">
491 <a name="brokengcc">Broken versions of GCC and other tools</a>
494 <div class="doc_text">
496 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
497 bugs in the compiler. In particular, several versions of GCC crash when trying
498 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
499 successfully with them (however, see important notes below). Other versions
500 of GCC will probably work as well. GCC versions listed
501 here are known to not work. If you are using one of these versions, please try
502 to upgrade your GCC to something more recent. If you run into a problem with a
503 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
504 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
505 of GCC you are using.
508 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
509 problems in the STL that effectively prevent it from compiling LLVM.
512 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
513 a bogus template error. This was fixed in later GCCs.</p>
515 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
516 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
517 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
519 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
520 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
521 to a newer version</a> if possible.</p>
522 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
523 possibly others) does not compile LLVM correctly (it appears that exception
524 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
525 to a newer version of GCC.</p>
526 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
527 code generator, causing an infinite loop in the llvm-gcc build when built
528 with optimizations enabled (i.e. a release build).</p>
529 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
530 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
531 correctly compiles LLVM at -O2. A work around is to build release LLVM
532 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
533 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
534 miscompiles portions of LLVM</a>.</p>
535 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
536 when building with optimizations enabled. It appears to work with
537 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
539 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
541 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
542 default with ENABLE_OPTIMIZED=1. To work around this, build with
543 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
544 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
545 compiling some files. At the time of this writing, GCC mainline (4.2)
546 did not share the problem.</p>
547 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
548 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
549 code. LLVM will appear to mostly work but will be buggy, e.g. failing
550 portions of its testsuite.</p>
551 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
552 platforms compiling md5.c gets a mangled constant.</p>
553 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
554 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
555 about symbols remaining in the table on destruction.</p>
556 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
557 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
558 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
559 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
560 with link errors when using this GCC version.</p>
561 <p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p>
562 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
563 when optimizations are turned on. The symptom is an infinite loop in
564 FoldingSetImpl::RemoveNode while running the code generator.</p>
565 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
566 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
567 defined in a discarded section. You can safely ignore these messages as they are
568 erroneous and the linkage is correct. These messages disappear using ld
571 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
572 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
573 causes huge link times (minutes instead of seconds) when building LLVM. We
574 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
576 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
577 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
578 which causes intermittent failures when building LLVM with position independent
579 code. The symptom is an error about cyclic dependencies. We recommend
580 upgrading to a newer version of Gold.</p>
586 <!-- *********************************************************************** -->
587 <div class="doc_section">
588 <a name="starting"><b>Getting Started with LLVM</b></a>
590 <!-- *********************************************************************** -->
592 <div class="doc_text">
594 <p>The remainder of this guide is meant to get you up and running with
595 LLVM and to give you some basic information about the LLVM environment.</p>
597 <p>The later sections of this guide describe the <a
598 href="#layout">general layout</a> of the the LLVM source tree, a <a
599 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
600 href="#links">links</a> to find more information about LLVM or to get
604 <!-- ======================================================================= -->
605 <div class="doc_subsection">
606 <a name="terminology">Terminology and Notation</a>
609 <div class="doc_text">
611 <p>Throughout this manual, the following names are used to denote paths
612 specific to the local system and working environment. <i>These are not
613 environment variables you need to set but just strings used in the rest
614 of this document below</i>. In any of the examples below, simply replace
615 each of these names with the appropriate pathname on your local system.
616 All these paths are absolute:</p>
621 This is the top level directory of the LLVM source tree.
626 This is the top level directory of the LLVM object tree (i.e. the
627 tree where object files and compiled programs will be placed. It
628 can be the same as SRC_ROOT).
633 This is where the LLVM GCC Front End is installed.
635 For the pre-built GCC front end binaries, the LLVMGCCDIR is
636 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
641 <!-- ======================================================================= -->
642 <div class="doc_subsection">
643 <a name="environment">Setting Up Your Environment</a>
646 <div class="doc_text">
649 In order to compile and use LLVM, you may need to set some environment
653 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
654 <dd>[Optional] This environment variable helps LLVM linking tools find the
655 locations of your bitcode libraries. It is provided only as a
656 convenience since you can specify the paths using the -L options of the
657 tools and the C/C++ front-end will automatically use the bitcode files
659 <tt>lib</tt> directory.</dd>
664 <!-- ======================================================================= -->
665 <div class="doc_subsection">
666 <a name="unpack">Unpacking the LLVM Archives</a>
669 <div class="doc_text">
672 If you have the LLVM distribution, you will need to unpack it before you
673 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
674 suite and the LLVM GCC front end compiled for your platform. There is an
675 additional test suite that is optional. Each file is a TAR archive that is
676 compressed with the gzip program.
679 <p>The files are as follows, with <em>x.y</em> marking the version number:
681 <dt><tt>llvm-x.y.tar.gz</tt></dt>
682 <dd>Source release for the LLVM libraries and tools.<br></dd>
684 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
685 <dd>Source release for the LLVM test suite.</dd>
687 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
688 <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
689 directory for build instructions.<br></dd>
691 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
692 <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
698 <!-- ======================================================================= -->
699 <div class="doc_subsection">
700 <a name="checkout">Checkout LLVM from Subversion</a>
703 <div class="doc_text">
705 <p>If you have access to our Subversion repository, you can get a fresh copy of
706 the entire source code. All you need to do is check it out from Subversion as
710 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
711 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
712 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
717 <p>This will create an '<tt>llvm</tt>' directory in the current
718 directory and fully populate it with the LLVM source code, Makefiles,
719 test directories, and local copies of documentation files.</p>
721 <p>If you want to get a specific release (as opposed to the most recent
722 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
723 '<tt>trunk</tt>'). The following releases are located in the following
724 subdirectories of the '<tt>tags</tt>' directory:</p>
727 <li>Release 2.5: <b>RELEASE_25</b></li>
728 <li>Release 2.4: <b>RELEASE_24</b></li>
729 <li>Release 2.3: <b>RELEASE_23</b></li>
730 <li>Release 2.2: <b>RELEASE_22</b></li>
731 <li>Release 2.1: <b>RELEASE_21</b></li>
732 <li>Release 2.0: <b>RELEASE_20</b></li>
733 <li>Release 1.9: <b>RELEASE_19</b></li>
734 <li>Release 1.8: <b>RELEASE_18</b></li>
735 <li>Release 1.7: <b>RELEASE_17</b></li>
736 <li>Release 1.6: <b>RELEASE_16</b></li>
737 <li>Release 1.5: <b>RELEASE_15</b></li>
738 <li>Release 1.4: <b>RELEASE_14</b></li>
739 <li>Release 1.3: <b>RELEASE_13</b></li>
740 <li>Release 1.2: <b>RELEASE_12</b></li>
741 <li>Release 1.1: <b>RELEASE_11</b></li>
742 <li>Release 1.0: <b>RELEASE_1</b></li>
745 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
746 you get it from the Subversion repository:</p>
748 <div class="doc_code">
751 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
755 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
756 configured by the LLVM configure script as well as automatically updated when
757 you run <tt>svn update</tt>.</p>
759 <p>If you would like to get the GCC front end source code, you can also get it
760 and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
761 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
765 <!-- ======================================================================= -->
766 <div class="doc_subsection">
767 <a name="installcf">Install the GCC Front End</a>
770 <div class="doc_text">
772 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
773 LLVM GCC front end from the binary distribution. It is used for running the
774 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
775 <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
776 main LLVM repository.</p>
778 <p>To install the GCC front end, do the following:</p>
781 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
782 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
786 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
787 llvm-g++ to some directory in your path. When you configure LLVM, it will
788 automatically detect llvm-gcc's presence (if it is in your path) enabling its
789 use in llvm-test. Note that you can always build or install llvm-gcc at any
790 pointer after building the main LLVM repository: just reconfigure llvm and
791 llvm-test will pick it up.
794 <p>The binary versions of the GCC front end may not suit all of your needs. For
795 example, the binary distribution may include an old version of a system header
796 file, not "fix" a header file that needs to be fixed for GCC, or it may be
797 linked with libraries not available on your system.</p>
799 <p>In cases like these, you may want to try <a
800 href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
801 much easier now than it was in the past.</p>
805 <!-- ======================================================================= -->
806 <div class="doc_subsection">
807 <a name="config">Local LLVM Configuration</a>
810 <div class="doc_text">
812 <p>Once checked out from the Subversion repository, the LLVM suite source
814 configured via the <tt>configure</tt> script. This script sets variables in the
815 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
816 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
817 the Makefiles needed to begin building LLVM.</p>
819 <p>The following environment variables are used by the <tt>configure</tt>
820 script to configure the build system:</p>
822 <table summary="LLVM configure script environment variables">
823 <tr><th>Variable</th><th>Purpose</th></tr>
826 <td>Tells <tt>configure</tt> which C compiler to use. By default,
827 <tt>configure</tt> will look for the first GCC C compiler in
828 <tt>PATH</tt>. Use this variable to override
829 <tt>configure</tt>'s default behavior.</td>
833 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
834 <tt>configure</tt> will look for the first GCC C++ compiler in
835 <tt>PATH</tt>. Use this variable to override
836 <tt>configure</tt>'s default behavior.</td>
840 <p>The following options can be used to set or enable LLVM specific options:</p>
843 <dt><i>--with-llvmgccdir</i></dt>
844 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
845 The value of this option should specify the full pathname of the C/C++ Front
846 End to be used. If this option is not provided, the PATH will be searched for
847 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
848 be inferred from the path found. If the option is not given, and no llvm-gcc
849 can be found in the path then a warning will be produced by
850 <tt>configure</tt> indicating this situation. LLVM may still be built with
851 the <tt>tools-only</tt> target but attempting to build the runtime libraries
852 will fail as these libraries require llvm-gcc and llvm-g++. See
853 <a href="#installcf">Install the GCC Front End</a> for details on installing
854 the C/C++ Front End. See
855 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
856 for details on building the C/C++ Front End.</dd>
857 <dt><i>--with-tclinclude</i></dt>
858 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
859 found. Use this if you have multiple tcl installations on your machine and you
860 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
861 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
862 option, the LLVM configure script will search for the tcl 8.4 and 8.3
866 <dt><i>--enable-optimized</i></dt>
868 Enables optimized compilation (debugging symbols are removed
869 and GCC optimization flags are enabled). Note that this is the default
870 setting if you are using the LLVM distribution. The default behavior
871 of an Subversion checkout is to use an unoptimized build (also known as a
875 <dt><i>--enable-debug-runtime</i></dt>
877 Enables debug symbols in the runtime libraries. The default is to strip
878 debug symbols from the runtime libraries.
880 <dt><i>--enable-jit</i></dt>
882 Compile the Just In Time (JIT) compiler functionality. This is not
884 on all platforms. The default is dependent on platform, so it is best
885 to explicitly enable it if you want it.
888 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
889 <dd>Controls which targets will be built and linked into llc. The default
890 value for <tt>target_options</tt> is "all" which builds and links all
891 available targets. The value "host-only" can be specified to build only a
892 native compiler (no cross-compiler targets available). The "native" target is
893 selected as the target of the build host. You can also specify a comma
894 separated list of target names that you want available in llc. The target
895 names use all lower case. The current set of targets is: <br>
896 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
898 <dt><i>--enable-doxygen</i></dt>
899 <dd>Look for the doxygen program and enable construction of doxygen based
900 documentation from the source code. This is disabled by default because
901 generating the documentation can take a long time and producess 100s of
902 megabytes of output.</dd>
903 <dt><i>--with-udis86</i></dt>
904 <dd>LLVM can use external disassembler library for various purposes (now it's
905 used only for examining code produced by JIT). This option will enable usage
906 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
907 bits) disassembler library.</dd>
910 <p>To configure LLVM, follow these steps:</p>
913 <li><p>Change directory into the object root directory:</p>
915 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
917 <li><p>Run the <tt>configure</tt> script located in the LLVM source
920 <div class="doc_code">
921 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
927 <!-- ======================================================================= -->
928 <div class="doc_subsection">
929 <a name="compile">Compiling the LLVM Suite Source Code</a>
932 <div class="doc_text">
934 <p>Once you have configured LLVM, you can build it. There are three types of
940 These builds are the default when one is using an Subversion checkout and
941 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
942 used during configuration). The build system will compile the tools and
943 libraries with debugging information. To get a Debug Build using the
944 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
945 to <tt>configure</tt>.
948 <dt>Release (Optimized) Builds
950 These builds are enabled with the <tt>--enable-optimized</tt> option to
951 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
952 <tt>gmake</tt> command line. For these builds, the build system will
953 compile the tools and libraries with GCC optimizations enabled and strip
954 debugging information from the libraries and executables it generates.
955 Note that Release Builds are default when using an LLVM distribution.
960 These builds are for use with profiling. They compile profiling
961 information into the code for use with programs like <tt>gprof</tt>.
962 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
963 on the <tt>gmake</tt> command line.
966 <p>Once you have LLVM configured, you can build it by entering the
967 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
969 <div class="doc_code"><pre>% gmake</pre></div>
971 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
972 are using a version of GCC that is known not to compile LLVM.</p>
975 If you have multiple processors in your machine, you may wish to use some of
976 the parallel build options provided by GNU Make. For example, you could use the
979 <div class="doc_code"><pre>% gmake -j2</pre></div>
981 <p>There are several special targets which are useful when working with the LLVM
985 <dt><tt>gmake clean</tt>
987 Removes all files generated by the build. This includes object files,
988 generated C/C++ files, libraries, and executables.
991 <dt><tt>gmake dist-clean</tt>
993 Removes everything that <tt>gmake clean</tt> does, but also removes files
994 generated by <tt>configure</tt>. It attempts to return the source tree to the
995 original state in which it was shipped.
998 <dt><tt>gmake install</tt>
1000 Installs LLVM header files, libraries, tools, and documentation in a
1002 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
1003 defaults to <tt>/usr/local</tt>.
1006 <dt><tt>gmake -C runtime install-bytecode</tt>
1008 Assuming you built LLVM into $OBJDIR, when this command is run, it will
1009 install bitcode libraries into the GCC front end's bitcode library
1010 directory. If you need to update your bitcode libraries,
1011 this is the target to use once you've built them.
1015 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1016 details on these <tt>make</tt> targets and descriptions of other targets
1019 <p>It is also possible to override default values from <tt>configure</tt> by
1020 declaring variables on the command line. The following are some examples:</p>
1023 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1025 Perform a Release (Optimized) build.
1028 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1030 Perform a Release (Optimized) build without assertions enabled.
1033 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1035 Perform a Debug build.
1038 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1040 Perform a Profiling build.
1043 <dt><tt>gmake VERBOSE=1</tt>
1045 Print what <tt>gmake</tt> is doing on standard output.
1048 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1049 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1050 the standard output. This also implies <tt>VERBOSE=1</tt>.
1054 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1055 it and any subdirectories that it contains. Entering any directory inside the
1056 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1057 that directory that is out of date.</p>
1061 <!-- ======================================================================= -->
1062 <div class="doc_subsection">
1063 <a name="cross-compile">Cross-Compiling LLVM</a>
1066 <div class="doc_text">
1067 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1068 executables and libraries to be hosted on a platform different from the
1069 platform where they are build (a Canadian Cross build). To configure a
1070 cross-compile, supply the configure script with <tt>--build</tt> and
1071 <tt>--host</tt> options that are different. The values of these options must
1072 be legal target triples that your GCC compiler supports.</p>
1074 <p>The result of such a build is executables that are not runnable on
1075 on the build host (--build option) but can be executed on the compile host
1076 (--host option).</p>
1079 <!-- ======================================================================= -->
1080 <div class="doc_subsection">
1081 <a name="objfiles">The Location of LLVM Object Files</a>
1084 <div class="doc_text">
1086 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1087 several LLVM builds. Hence, it is possible to build LLVM for several different
1088 platforms or configurations using the same source tree.</p>
1090 <p>This is accomplished in the typical autoconf manner:</p>
1093 <li><p>Change directory to where the LLVM object files should live:</p>
1095 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1097 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1100 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1103 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1104 named after the build type:</p>
1111 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1113 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1121 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1123 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1131 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1133 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1139 <!-- ======================================================================= -->
1140 <div class="doc_subsection">
1141 <a name="optionalconfig">Optional Configuration Items</a>
1144 <div class="doc_text">
1147 If you're running on a Linux system that supports the "<a
1148 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1149 module, and you have root access on the system, you can set your system up to
1150 execute LLVM bitcode files directly. To do this, use commands like this (the
1151 first command may not be required if you are already using the module):</p>
1153 <div class="doc_code">
1155 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1156 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1157 $ chmod u+x hello.bc (if needed)
1163 This allows you to execute LLVM bitcode files directly. Thanks to Jack
1164 Cummings for pointing this out!
1170 <!-- *********************************************************************** -->
1171 <div class="doc_section">
1172 <a name="layout"><b>Program Layout</b></a>
1174 <!-- *********************************************************************** -->
1176 <div class="doc_text">
1178 <p>One useful source of information about the LLVM source base is the LLVM <a
1179 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1180 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1181 The following is a brief introduction to code layout:</p>
1185 <!-- ======================================================================= -->
1186 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1187 <div class="doc_text">
1188 <p>This directory contains some simple examples of how to use the LLVM IR and
1192 <!-- ======================================================================= -->
1193 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1194 <div class="doc_text">
1196 <p>This directory contains public header files exported from the LLVM
1197 library. The three main subdirectories of this directory are:</p>
1200 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1201 <dd>This directory contains all of the LLVM specific header files. This
1202 directory also has subdirectories for different portions of LLVM:
1203 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1206 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1207 <dd>This directory contains generic support libraries that are provided with
1208 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1209 and a Command Line option processing library store their header files here.
1212 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1213 <dd>This directory contains header files configured by the <tt>configure</tt>
1214 script. They wrap "standard" UNIX and C header files. Source code can
1215 include these header files which automatically take care of the conditional
1216 #includes that the <tt>configure</tt> script generates.</dd>
1220 <!-- ======================================================================= -->
1221 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1222 <div class="doc_text">
1224 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1225 almost all code exists in libraries, making it very easy to share code among the
1226 different <a href="#tools">tools</a>.</p>
1229 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1230 <dd> This directory holds the core LLVM source files that implement core
1231 classes like Instruction and BasicBlock.</dd>
1233 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1234 <dd>This directory holds the source code for the LLVM assembly language parser
1237 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1238 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1240 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1241 different program analyses, such as Dominator Information, Call Graphs,
1242 Induction Variables, Interval Identification, Natural Loop Identification,
1245 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1246 <dd> This directory contains the source code for the LLVM to LLVM program
1247 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1248 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1249 Elimination, and many others.</dd>
1251 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1252 <dd> This directory contains files that describe various target architectures
1253 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1254 directory holds the X86 machine description while
1255 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1257 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1258 <dd> This directory contains the major parts of the code generator: Instruction
1259 Selector, Instruction Scheduling, and Register Allocation.</dd>
1261 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1262 <dd> This directory contains the source level debugger library that makes
1263 it possible to instrument LLVM programs so that a debugger could identify
1264 source code locations at which the program is executing.</dd>
1266 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1267 <dd> This directory contains libraries for executing LLVM bitcode directly
1268 at runtime in both interpreted and JIT compiled fashions.</dd>
1270 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1271 <dd> This directory contains the source code that corresponds to the header
1272 files located in <tt>llvm/include/Support/</tt>.</dd>
1274 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1275 <dd>This directory contains the operating system abstraction layer that
1276 shields LLVM from platform-specific coding.</dd>
1281 <!-- ======================================================================= -->
1282 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1283 <div class="doc_text">
1284 <p>This directory contains projects that are not strictly part of LLVM but are
1285 shipped with LLVM. This is also the directory where you should create your own
1286 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1287 to set up your own project.</p>
1290 <!-- ======================================================================= -->
1291 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1292 <div class="doc_text">
1294 <p>This directory contains libraries which are compiled into LLVM bitcode and
1295 used when linking programs with the GCC front end. Most of these libraries are
1296 skeleton versions of real libraries; for example, libc is a stripped down
1297 version of glibc.</p>
1299 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1304 <!-- ======================================================================= -->
1305 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1306 <div class="doc_text">
1307 <p>This directory contains feature and regression tests and other basic sanity
1308 checks on the LLVM infrastructure. These are intended to run quickly and cover
1309 a lot of territory without being exhaustive.</p>
1312 <!-- ======================================================================= -->
1313 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1314 <div class="doc_text">
1315 <p>This is not a directory in the normal llvm module; it is a separate
1317 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1319 module contains a comprehensive correctness, performance, and benchmarking
1321 suite for LLVM. It is a separate Subversion module because not every LLVM
1323 interested in downloading or building such a comprehensive test suite. For
1324 further details on this test suite, please see the
1325 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1328 <!-- ======================================================================= -->
1329 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1330 <div class="doc_text">
1332 <p>The <b>tools</b> directory contains the executables built out of the
1333 libraries above, which form the main part of the user interface. You can
1334 always get help for a tool by typing <tt>tool_name --help</tt>. The
1335 following is a brief introduction to the most important tools. More detailed
1336 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1340 <dt><tt><b>bugpoint</b></tt></dt>
1341 <dd><tt>bugpoint</tt> is used to debug
1342 optimization passes or code generation backends by narrowing down the
1343 given test case to the minimum number of passes and/or instructions that
1344 still cause a problem, whether it is a crash or miscompilation. See <a
1345 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1346 on using <tt>bugpoint</tt>.</dd>
1348 <dt><tt><b>llvmc</b></tt></dt>
1349 <dd>The LLVM Compiler Driver. This program can
1350 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1351 pre-processing, translation, optimization, assembly, and linking of programs
1352 all from one command line. <tt>llvmc</tt> also takes care of processing the
1353 dependent libraries found in bitcode. This reduces the need to get the
1354 traditional <tt>-l<name></tt> options right on the command line. Please
1355 note that this tool, while functional, is still experimental and not feature
1358 <dt><tt><b>llvm-ar</b></tt></dt>
1359 <dd>The archiver produces an archive containing
1360 the given LLVM bitcode files, optionally with an index for faster
1363 <dt><tt><b>llvm-as</b></tt></dt>
1364 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1367 <dt><tt><b>llvm-dis</b></tt></dt>
1368 <dd>The disassembler transforms the LLVM bitcode to human readable
1371 <dt><tt><b>llvm-ld</b></tt></dt>
1372 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1373 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1374 optimizations and allows optimization modules to be loaded and run so that
1375 language specific optimizations can be applied at link time.</dd>
1377 <dt><tt><b>llvm-link</b></tt></dt>
1378 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1379 a single program.</dd>
1381 <dt><tt><b>lli</b></tt></dt>
1382 <dd><tt>lli</tt> is the LLVM interpreter, which
1383 can directly execute LLVM bitcode (although very slowly...). For architectures
1384 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1385 will function as a Just-In-Time compiler (if the functionality was compiled
1386 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1388 <dt><tt><b>llc</b></tt></dt>
1389 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1390 translates LLVM bitcode to a native code assembly file or to C code (with
1391 the -march=c option).</dd>
1393 <dt><tt><b>llvm-gcc</b></tt></dt>
1394 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1395 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1396 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1397 usual machine code output. It works just like any other GCC compiler,
1398 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1399 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1400 separate Subversion module.</dd>
1402 <dt><tt><b>opt</b></tt></dt>
1403 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1404 transformations (which are specified on the command line), and then outputs
1405 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1406 get a list of the program transformations available in LLVM.<br>
1407 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1408 LLVM bitcode file and print out the results. It is primarily useful for
1409 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1413 <!-- ======================================================================= -->
1414 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1415 <div class="doc_text">
1417 <p>This directory contains utilities for working with LLVM source code, and some
1418 of the utilities are actually required as part of the build process because they
1419 are code generators for parts of LLVM infrastructure.</p>
1422 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1423 that finds differences between code that LLC generates and code that LLI
1424 generates. This is a useful tool if you are debugging one of them,
1425 assuming that the other generates correct output. For the full user
1426 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1428 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1429 syntax-highlighting files which will work with Emacs and XEmacs editors,
1430 providing syntax highlighting support for LLVM assembly files and TableGen
1431 description files. For information on how to use the syntax files, consult
1432 the <tt>README</tt> file in that directory.<br><br>
1434 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1435 and outputs all non-generated source files, which is useful if one wishes
1436 to do a lot of development across directories and does not want to
1437 individually find each file. One way to use it is to run, for example:
1438 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1441 <dt><tt><b>llvmgrep</b></tt></dt>
1442 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1443 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1444 line. This is a very efficient way of searching the source base for a
1445 particular regular expression.</dd>
1447 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1448 files in the current directory and then compiles and links the tool that
1449 is the first argument. For example, assuming you are in the directory
1450 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1451 simply running <tt>makellvm llc</tt> will make a build of the current
1452 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1453 causing a re-linking of LLC.<br><br>
1455 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1456 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1457 cron script to generate nightly status reports of the functionality of
1458 tools, and the results can be seen by following the appropriate link on
1459 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1461 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1462 the tool used to generate register descriptions, instruction set
1463 descriptions, and even assemblers from common TableGen description
1466 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1467 syntax-highlighting files which will work with the VIM editor, providing
1468 syntax highlighting support for LLVM assembly files and TableGen
1469 description files. For information on how to use the syntax files, consult
1470 the <tt>README</tt> file in that directory.<br><br>
1476 <!-- ======================================================================= -->
1477 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1478 <div class="doc_text">
1479 <p>This directory contains build scripts and project files for use with
1480 Visual C++. This allows developers on Windows to build LLVM without the need
1481 for Cygwin. The contents of this directory should be considered experimental
1485 <!-- *********************************************************************** -->
1486 <div class="doc_section">
1487 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1489 <!-- *********************************************************************** -->
1491 <div class="doc_text">
1492 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1493 so we only include instructions for llvm-gcc4.
1496 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1497 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1498 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1499 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1500 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1504 <!-- ======================================================================= -->
1505 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1507 <div class="doc_text">
1510 <li><p>First, create a simple C file, name it 'hello.c':</p>
1512 <div class="doc_code">
1514 #include <stdio.h>
1517 printf("hello world\n");
1522 <li><p>Next, compile the C file into a native executable:</p>
1524 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1526 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1527 -c arguments work as usual (producing a native .s or .o file,
1528 respectively).</p></li>
1530 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1532 <div class="doc_code">
1533 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1535 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1536 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1537 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1538 the bitcode file.</p>
1540 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1543 <li><p>Run the program in both forms. To run the program, use:</p>
1545 <div class="doc_code"><pre>% ./hello</pre></div>
1549 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1551 <p>The second examples shows how to invoke the LLVM JIT, <a
1552 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1554 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1557 <div class="doc_code">
1558 <pre>llvm-dis < hello.bc | less</pre>
1561 <li><p>Compile the program to native assembly using the LLC code
1564 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1566 <li><p>Assemble the native assembly language file into a program:</p>
1568 <div class="doc_code">
1570 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1572 <b>Others:</b> % gcc hello.s -o hello.native
1576 <li><p>Execute the native code program:</p>
1578 <div class="doc_code"><pre>% ./hello.native</pre></div>
1580 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1581 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1589 <!-- *********************************************************************** -->
1590 <div class="doc_section">
1591 <a name="problems">Common Problems</a>
1593 <!-- *********************************************************************** -->
1595 <div class="doc_text">
1597 <p>If you are having problems building or using LLVM, or if you have any other
1598 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1599 Asked Questions</a> page.</p>
1603 <!-- *********************************************************************** -->
1604 <div class="doc_section">
1605 <a name="links">Links</a>
1607 <!-- *********************************************************************** -->
1609 <div class="doc_text">
1611 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1612 some simple things... there are many more interesting and complicated things
1613 that you can do that aren't documented here (but we'll gladly accept a patch
1614 if you want to write something up!). For more information about LLVM, check
1618 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1619 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1620 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1621 that Uses LLVM</a></li>
1626 <!-- *********************************************************************** -->
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1635 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1636 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1637 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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