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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>V9 (Ultrasparc)</td>
230 <td>x86<sup><a href="#pf_1">1</a></sup></td>
234 <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
239 <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
245 <td>Cygwin/Win32</td>
246 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a></sup></td>
247 <td>GCC 3.4.X, binutils 2.15</td>
251 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,<a href="#pf_8">8</a></sup></td>
252 <td>GCC 3.4.X, binutils 2.15</td>
261 <p>LLVM has partial support for the following platforms:</p>
263 <table summary="LLVM partial platform support">
271 <td>x86<sup><a href="#pf_1">1</a></sup></td>
272 <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
274 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
279 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
285 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
290 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
291 <td>Itanium (IA-64)</td>
295 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
296 <td>Itanium (IA-64)</td>
303 <div class="doc_notes">
305 <li><a name="pf_1">Code generation supported for Pentium processors and
307 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
308 <li><a name="pf_3">No native code generation</a></li>
309 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
310 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
311 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
312 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
313 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
314 preventing LLVM from building correctly. Several workarounds have been
315 introduced into LLVM build system, but the bug can occur anytime in the
316 future. We highly recommend that you rebuild your current binutils with the
317 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
318 Binutils bugzilla</a>, if it wasn't already applied.</li>
319 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
320 internal LLVM assert messages when compiled for Release at optimization
321 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
322 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
323 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
327 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
328 mode, depending on the system (it is so large because of all the debugging
329 information and the fact that the libraries are statically linked into multiple
330 tools). If you do not need many of the tools and you are space-conscious, you
331 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
332 requires considerably less space.</p>
334 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
335 guaranteed to do so. If compilation is successful, the LLVM utilities should be
336 able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
337 generation should work as well, although the generated native code may not work
338 on your platform.</p>
340 <p>The GCC front end is not very portable at the moment. If you want to get it
341 to work on another platform, you can download a copy of the source and <a
342 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
346 <!-- ======================================================================= -->
347 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
348 <div class="doc_text">
349 <p>Compiling LLVM requires that you have several software packages
350 installed. The table below lists those required packages. The Package column
351 is the usual name for the software package that LLVM depends on. The Version
352 column provides "known to work" versions of the package. The Notes column
353 describes how LLVM uses the package and provides other details.</p>
354 <table summary="Packages required to compile LLVM">
355 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
358 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
359 <td>3.79, 3.79.1</td>
360 <td>Makefile/build processor</td>
364 <td><a href="http://gcc.gnu.org">GCC</a></td>
366 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
370 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
372 <td>For building the CFE</td>
376 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
378 <td>Subversion 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="sf1">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 Subversion if you intend to build from the
438 latest LLVM sources. If you're working from a release distribution, you
439 don't need Subversion.</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>find</b> - find files/dirs in a file system</li>
462 <li><b>grep</b> - regular expression search utility</li>
463 <li><b>gzip*</b> - gzip command for distribution generation</li>
464 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
465 <li><b>install</b> - install directories/files </li>
466 <li><b>mkdir</b> - create a directory</li>
467 <li><b>mv</b> - move (rename) files</li>
468 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
469 <li><b>rm</b> - remove (delete) files and directories</li>
470 <li><b>sed</b> - stream editor for transforming output</li>
471 <li><b>sh</b> - Bourne shell for make build scripts</li>
472 <li><b>tar</b> - tape archive for distribution generation</li>
473 <li><b>test</b> - test things in file system</li>
474 <li><b>unzip*</b> - unzip command for distribution checking</li>
475 <li><b>zip*</b> - zip command for distribution generation</li>
479 <!-- ======================================================================= -->
480 <div class="doc_subsection">
481 <a name="brokengcc">Broken versions of GCC and other tools</a>
484 <div class="doc_text">
486 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
487 bugs in the compiler. In particular, several versions of GCC crash when trying
488 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
489 successfully with them (however, see important notes below). Other versions
490 of GCC will probably work as well. GCC versions listed
491 here are known to not work. If you are using one of these versions, please try
492 to upgrade your GCC to something more recent. If you run into a problem with a
493 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
494 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
495 of GCC you are using.
498 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
499 problems in the STL that effectively prevent it from compiling LLVM.
502 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
503 a bogus template error. This was fixed in later GCCs.</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="GCCFEBuildInstrs.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>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
517 code generator, causing an infinite loop in the llvm-gcc build when built
518 with optimizations enabled (i.e. a release build).</p>
519 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
520 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
521 correctly compiles LLVM at -O2. A work around is to build release LLVM
522 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
523 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
524 miscompiles portions of LLVM</a>.</p>
525 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
526 when building with optimizations enabled. It appears to work with
527 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
529 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
531 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
532 default with ENABLE_OPTIMIZED=1. To work around this, build with
533 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
534 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
535 compiling some files. At the time of this writing, GCC mainline (4.2)
536 did not share the problem.</p>
537 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
538 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
539 code. LLVM will appear to mostly work but will be buggy, e.g. failing
540 portions of its testsuite.</p>
541 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
542 platforms compiling md5.c gets a mangled constant.</p>
543 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
544 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
545 about symbols remaining in the table on destruction.</p>
546 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
547 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
548 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
549 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
550 with link errors when using this GCC version.</p>
551 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
552 when optimizations are turned on. The symptom is an infinite loop in
553 FoldingSetImpl::RemoveNode while running the code generator.
554 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
555 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
556 defined in a discarded section. You can safely ignore these messages as they are
557 erroneous and the linkage is correct. These messages disappear using ld
560 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
561 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
562 causes huge link times (minutes instead of seconds) when building LLVM. We
563 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
565 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
566 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
567 which causes intermittent failures when building LLVM with position independent
568 code. The symptom is an error about cyclic dependencies. We recommend
569 upgrading to a newer version of Gold.</p>
575 <!-- *********************************************************************** -->
576 <div class="doc_section">
577 <a name="starting"><b>Getting Started with LLVM</b></a>
579 <!-- *********************************************************************** -->
581 <div class="doc_text">
583 <p>The remainder of this guide is meant to get you up and running with
584 LLVM and to give you some basic information about the LLVM environment.</p>
586 <p>The later sections of this guide describe the <a
587 href="#layout">general layout</a> of the the LLVM source tree, a <a
588 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
589 href="#links">links</a> to find more information about LLVM or to get
593 <!-- ======================================================================= -->
594 <div class="doc_subsection">
595 <a name="terminology">Terminology and Notation</a>
598 <div class="doc_text">
600 <p>Throughout this manual, the following names are used to denote paths
601 specific to the local system and working environment. <i>These are not
602 environment variables you need to set but just strings used in the rest
603 of this document below</i>. In any of the examples below, simply replace
604 each of these names with the appropriate pathname on your local system.
605 All these paths are absolute:</p>
610 This is the top level directory of the LLVM source tree.
615 This is the top level directory of the LLVM object tree (i.e. the
616 tree where object files and compiled programs will be placed. It
617 can be the same as SRC_ROOT).
622 This is where the LLVM GCC Front End is installed.
624 For the pre-built GCC front end binaries, the LLVMGCCDIR is
625 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
630 <!-- ======================================================================= -->
631 <div class="doc_subsection">
632 <a name="environment">Setting Up Your Environment</a>
635 <div class="doc_text">
638 In order to compile and use LLVM, you may need to set some environment
642 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
643 <dd>[Optional] This environment variable helps LLVM linking tools find the
644 locations of your bitcode libraries. It is provided only as a
645 convenience since you can specify the paths using the -L options of the
646 tools and the C/C++ front-end will automatically use the bitcode files
648 <tt>lib</tt> directory.</dd>
653 <!-- ======================================================================= -->
654 <div class="doc_subsection">
655 <a name="unpack">Unpacking the LLVM Archives</a>
658 <div class="doc_text">
661 If you have the LLVM distribution, you will need to unpack it before you
662 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
663 suite and the LLVM GCC front end compiled for your platform. There is an
664 additional test suite that is optional. Each file is a TAR archive that is
665 compressed with the gzip program.
668 <p>The files are as follows, with <em>x.y</em> marking the version number:
670 <dt><tt>llvm-x.y.tar.gz</tt></dt>
671 <dd>Source release for the LLVM libraries and tools.<br></dd>
673 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
674 <dd>Source release for the LLVM test suite.</dd>
676 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
677 <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
678 directory for build instructions.<br></dd>
680 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
681 <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
687 <!-- ======================================================================= -->
688 <div class="doc_subsection">
689 <a name="checkout">Checkout LLVM from Subversion</a>
692 <div class="doc_text">
694 <p>If you have access to our Subversion repository, you can get a fresh copy of
695 the entire source code. All you need to do is check it out from Subversion as
699 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
700 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
701 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
706 <p>This will create an '<tt>llvm</tt>' directory in the current
707 directory and fully populate it with the LLVM source code, Makefiles,
708 test directories, and local copies of documentation files.</p>
710 <p>If you want to get a specific release (as opposed to the most recent
711 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
712 '<tt>trunk</tt>'). The following releases are located in the following
713 subdirectories of the '<tt>tags</tt>' directory:</p>
716 <li>Release 2.5: <b>RELEASE_25</b></li>
717 <li>Release 2.4: <b>RELEASE_24</b></li>
718 <li>Release 2.3: <b>RELEASE_23</b></li>
719 <li>Release 2.2: <b>RELEASE_22</b></li>
720 <li>Release 2.1: <b>RELEASE_21</b></li>
721 <li>Release 2.0: <b>RELEASE_20</b></li>
722 <li>Release 1.9: <b>RELEASE_19</b></li>
723 <li>Release 1.8: <b>RELEASE_18</b></li>
724 <li>Release 1.7: <b>RELEASE_17</b></li>
725 <li>Release 1.6: <b>RELEASE_16</b></li>
726 <li>Release 1.5: <b>RELEASE_15</b></li>
727 <li>Release 1.4: <b>RELEASE_14</b></li>
728 <li>Release 1.3: <b>RELEASE_13</b></li>
729 <li>Release 1.2: <b>RELEASE_12</b></li>
730 <li>Release 1.1: <b>RELEASE_11</b></li>
731 <li>Release 1.0: <b>RELEASE_1</b></li>
734 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
735 you get it from the Subversion repository:</p>
737 <div class="doc_code">
740 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
744 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
745 configured by the LLVM configure script as well as automatically updated when
746 you run <tt>svn update</tt>.</p>
748 <p>If you would like to get the GCC front end source code, you can also get it
749 and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
750 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
754 <!-- ======================================================================= -->
755 <div class="doc_subsection">
756 <a name="installcf">Install the GCC Front End</a>
759 <div class="doc_text">
761 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
762 LLVM GCC front end from the binary distribution. It is used for running the
763 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
764 <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
765 main LLVM repository.</p>
767 <p>To install the GCC front end, do the following:</p>
770 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
771 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
775 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
776 llvm-g++ to some directory in your path. When you configure LLVM, it will
777 automatically detect llvm-gcc's presence (if it is in your path) enabling its
778 use in llvm-test. Note that you can always build or install llvm-gcc at any
779 pointer after building the main LLVM repository: just reconfigure llvm and
780 llvm-test will pick it up.
783 <p>The binary versions of the GCC front end may not suit all of your needs. For
784 example, the binary distribution may include an old version of a system header
785 file, not "fix" a header file that needs to be fixed for GCC, or it may be
786 linked with libraries not available on your system.</p>
788 <p>In cases like these, you may want to try <a
789 href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
790 much easier now than it was in the past.</p>
794 <!-- ======================================================================= -->
795 <div class="doc_subsection">
796 <a name="config">Local LLVM Configuration</a>
799 <div class="doc_text">
801 <p>Once checked out from the Subversion repository, the LLVM suite source
803 configured via the <tt>configure</tt> script. This script sets variables in the
804 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
805 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
806 the Makefiles needed to begin building LLVM.</p>
808 <p>The following environment variables are used by the <tt>configure</tt>
809 script to configure the build system:</p>
811 <table summary="LLVM configure script environment variables">
812 <tr><th>Variable</th><th>Purpose</th></tr>
815 <td>Tells <tt>configure</tt> which C compiler to use. By default,
816 <tt>configure</tt> will look for the first GCC C compiler in
817 <tt>PATH</tt>. Use this variable to override
818 <tt>configure</tt>'s default behavior.</td>
822 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
823 <tt>configure</tt> will look for the first GCC C++ compiler in
824 <tt>PATH</tt>. Use this variable to override
825 <tt>configure</tt>'s default behavior.</td>
829 <p>The following options can be used to set or enable LLVM specific options:</p>
832 <dt><i>--with-llvmgccdir</i></dt>
833 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
834 The value of this option should specify the full pathname of the C/C++ Front
835 End to be used. If this option is not provided, the PATH will be searched for
836 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
837 be inferred from the path found. If the option is not given, and no llvm-gcc
838 can be found in the path then a warning will be produced by
839 <tt>configure</tt> indicating this situation. LLVM may still be built with
840 the <tt>tools-only</tt> target but attempting to build the runtime libraries
841 will fail as these libraries require llvm-gcc and llvm-g++. See
842 <a href="#installcf">Install the GCC Front End</a> for details on installing
843 the C/C++ Front End. See
844 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
845 for details on building the C/C++ Front End.</dd>
846 <dt><i>--with-tclinclude</i></dt>
847 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
848 found. Use this if you have multiple tcl installations on your machine and you
849 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
850 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
851 option, the LLVM configure script will search for the tcl 8.4 and 8.3
855 <dt><i>--enable-optimized</i></dt>
857 Enables optimized compilation (debugging symbols are removed
858 and GCC optimization flags are enabled). Note that this is the default
859 setting if you are using the LLVM distribution. The default behavior
860 of an Subversion checkout is to use an unoptimized build (also known as a
864 <dt><i>--enable-debug-runtime</i></dt>
866 Enables debug symbols in the runtime libraries. The default is to strip
867 debug symbols from the runtime libraries.
869 <dt><i>--enable-jit</i></dt>
871 Compile the Just In Time (JIT) compiler functionality. This is not
873 on all platforms. The default is dependent on platform, so it is best
874 to explicitly enable it if you want it.
877 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
878 <dd>Controls which targets will be built and linked into llc. The default
879 value for <tt>target_options</tt> is "all" which builds and links all
880 available targets. The value "host-only" can be specified to build only a
881 native compiler (no cross-compiler targets available). The "native" target is
882 selected as the target of the build host. You can also specify a comma
883 separated list of target names that you want available in llc. The target
884 names use all lower case. The current set of targets is: <br>
885 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
887 <dt><i>--enable-doxygen</i></dt>
888 <dd>Look for the doxygen program and enable construction of doxygen based
889 documentation from the source code. This is disabled by default because
890 generating the documentation can take a long time and producess 100s of
891 megabytes of output.</dd>
892 <dt><i>--with-udis86</i></dt>
893 <dd>LLVM can use external disassembler library for various purposes (now it's
894 used only for examining code produced by JIT). This option will enable usage
895 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
896 bits) disassembler library.</dd>
899 <p>To configure LLVM, follow these steps:</p>
902 <li><p>Change directory into the object root directory:</p>
904 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
906 <li><p>Run the <tt>configure</tt> script located in the LLVM source
909 <div class="doc_code">
910 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
916 <!-- ======================================================================= -->
917 <div class="doc_subsection">
918 <a name="compile">Compiling the LLVM Suite Source Code</a>
921 <div class="doc_text">
923 <p>Once you have configured LLVM, you can build it. There are three types of
929 These builds are the default when one is using an Subversion checkout and
930 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
931 used during configuration). The build system will compile the tools and
932 libraries with debugging information. To get a Debug Build using the
933 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
934 to <tt>configure</tt>.
937 <dt>Release (Optimized) Builds
939 These builds are enabled with the <tt>--enable-optimized</tt> option to
940 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
941 <tt>gmake</tt> command line. For these builds, the build system will
942 compile the tools and libraries with GCC optimizations enabled and strip
943 debugging information from the libraries and executables it generates.
944 Note that Release Builds are default when using an LLVM distribution.
949 These builds are for use with profiling. They compile profiling
950 information into the code for use with programs like <tt>gprof</tt>.
951 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
952 on the <tt>gmake</tt> command line.
955 <p>Once you have LLVM configured, you can build it by entering the
956 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
958 <div class="doc_code"><pre>% gmake</pre></div>
960 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
961 are using a version of GCC that is known not to compile LLVM.</p>
964 If you have multiple processors in your machine, you may wish to use some of
965 the parallel build options provided by GNU Make. For example, you could use the
968 <div class="doc_code"><pre>% gmake -j2</pre></div>
970 <p>There are several special targets which are useful when working with the LLVM
974 <dt><tt>gmake clean</tt>
976 Removes all files generated by the build. This includes object files,
977 generated C/C++ files, libraries, and executables.
980 <dt><tt>gmake dist-clean</tt>
982 Removes everything that <tt>gmake clean</tt> does, but also removes files
983 generated by <tt>configure</tt>. It attempts to return the source tree to the
984 original state in which it was shipped.
987 <dt><tt>gmake install</tt>
989 Installs LLVM header files, libraries, tools, and documentation in a
991 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
992 defaults to <tt>/usr/local</tt>.
995 <dt><tt>gmake -C runtime install-bytecode</tt>
997 Assuming you built LLVM into $OBJDIR, when this command is run, it will
998 install bitcode libraries into the GCC front end's bitcode library
999 directory. If you need to update your bitcode libraries,
1000 this is the target to use once you've built them.
1004 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1005 details on these <tt>make</tt> targets and descriptions of other targets
1008 <p>It is also possible to override default values from <tt>configure</tt> by
1009 declaring variables on the command line. The following are some examples:</p>
1012 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1014 Perform a Release (Optimized) build.
1017 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1019 Perform a Release (Optimized) build without assertions enabled.
1022 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1024 Perform a Debug build.
1027 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1029 Perform a Profiling build.
1032 <dt><tt>gmake VERBOSE=1</tt>
1034 Print what <tt>gmake</tt> is doing on standard output.
1037 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1038 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1039 the standard output. This also implies <tt>VERBOSE=1</tt>.
1043 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1044 it and any subdirectories that it contains. Entering any directory inside the
1045 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1046 that directory that is out of date.</p>
1050 <!-- ======================================================================= -->
1051 <div class="doc_subsection">
1052 <a name="cross-compile">Cross-Compiling LLVM</a>
1055 <div class="doc_text">
1056 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1057 executables and libraries to be hosted on a platform different from the
1058 platform where they are build (a Canadian Cross build). To configure a
1059 cross-compile, supply the configure script with <tt>--build</tt> and
1060 <tt>--host</tt> options that are different. The values of these options must
1061 be legal target triples that your GCC compiler supports.</p>
1063 <p>The result of such a build is executables that are not runnable on
1064 on the build host (--build option) but can be executed on the compile host
1065 (--host option).</p>
1068 <!-- ======================================================================= -->
1069 <div class="doc_subsection">
1070 <a name="objfiles">The Location of LLVM Object Files</a>
1073 <div class="doc_text">
1075 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1076 several LLVM builds. Hence, it is possible to build LLVM for several different
1077 platforms or configurations using the same source tree.</p>
1079 <p>This is accomplished in the typical autoconf manner:</p>
1082 <li><p>Change directory to where the LLVM object files should live:</p>
1084 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1086 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1089 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1092 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1093 named after the build type:</p>
1100 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1102 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1110 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1112 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1120 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1122 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1128 <!-- ======================================================================= -->
1129 <div class="doc_subsection">
1130 <a name="optionalconfig">Optional Configuration Items</a>
1133 <div class="doc_text">
1136 If you're running on a Linux system that supports the "<a
1137 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1138 module, and you have root access on the system, you can set your system up to
1139 execute LLVM bitcode files directly. To do this, use commands like this (the
1140 first command may not be required if you are already using the module):</p>
1142 <div class="doc_code">
1144 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1145 $ echo ':llvm:M::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1146 $ chmod u+x hello.bc (if needed)
1152 This allows you to execute LLVM bitcode files directly. Thanks to Jack
1153 Cummings for pointing this out!
1159 <!-- *********************************************************************** -->
1160 <div class="doc_section">
1161 <a name="layout"><b>Program Layout</b></a>
1163 <!-- *********************************************************************** -->
1165 <div class="doc_text">
1167 <p>One useful source of information about the LLVM source base is the LLVM <a
1168 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1169 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1170 The following is a brief introduction to code layout:</p>
1174 <!-- ======================================================================= -->
1175 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1176 <div class="doc_text">
1177 <p>This directory contains some simple examples of how to use the LLVM IR and
1181 <!-- ======================================================================= -->
1182 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1183 <div class="doc_text">
1185 <p>This directory contains public header files exported from the LLVM
1186 library. The three main subdirectories of this directory are:</p>
1189 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1190 <dd>This directory contains all of the LLVM specific header files. This
1191 directory also has subdirectories for different portions of LLVM:
1192 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1195 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1196 <dd>This directory contains generic support libraries that are provided with
1197 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1198 and a Command Line option processing library store their header files here.
1201 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1202 <dd>This directory contains header files configured by the <tt>configure</tt>
1203 script. They wrap "standard" UNIX and C header files. Source code can
1204 include these header files which automatically take care of the conditional
1205 #includes that the <tt>configure</tt> script generates.</dd>
1209 <!-- ======================================================================= -->
1210 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1211 <div class="doc_text">
1213 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1214 almost all code exists in libraries, making it very easy to share code among the
1215 different <a href="#tools">tools</a>.</p>
1218 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1219 <dd> This directory holds the core LLVM source files that implement core
1220 classes like Instruction and BasicBlock.</dd>
1222 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1223 <dd>This directory holds the source code for the LLVM assembly language parser
1226 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1227 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1229 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1230 different program analyses, such as Dominator Information, Call Graphs,
1231 Induction Variables, Interval Identification, Natural Loop Identification,
1234 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1235 <dd> This directory contains the source code for the LLVM to LLVM program
1236 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1237 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1238 Elimination, and many others.</dd>
1240 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1241 <dd> This directory contains files that describe various target architectures
1242 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1243 directory holds the X86 machine description while
1244 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1246 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1247 <dd> This directory contains the major parts of the code generator: Instruction
1248 Selector, Instruction Scheduling, and Register Allocation.</dd>
1250 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1251 <dd> This directory contains the source level debugger library that makes
1252 it possible to instrument LLVM programs so that a debugger could identify
1253 source code locations at which the program is executing.</dd>
1255 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1256 <dd> This directory contains libraries for executing LLVM bitcode directly
1257 at runtime in both interpreted and JIT compiled fashions.</dd>
1259 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1260 <dd> This directory contains the source code that corresponds to the header
1261 files located in <tt>llvm/include/Support/</tt>.</dd>
1263 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1264 <dd>This directory contains the operating system abstraction layer that
1265 shields LLVM from platform-specific coding.</dd>
1270 <!-- ======================================================================= -->
1271 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1272 <div class="doc_text">
1273 <p>This directory contains projects that are not strictly part of LLVM but are
1274 shipped with LLVM. This is also the directory where you should create your own
1275 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1276 to set up your own project.</p>
1279 <!-- ======================================================================= -->
1280 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1281 <div class="doc_text">
1283 <p>This directory contains libraries which are compiled into LLVM bitcode and
1284 used when linking programs with the GCC front end. Most of these libraries are
1285 skeleton versions of real libraries; for example, libc is a stripped down
1286 version of glibc.</p>
1288 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1293 <!-- ======================================================================= -->
1294 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1295 <div class="doc_text">
1296 <p>This directory contains feature and regression tests and other basic sanity
1297 checks on the LLVM infrastructure. These are intended to run quickly and cover
1298 a lot of territory without being exhaustive.</p>
1301 <!-- ======================================================================= -->
1302 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1303 <div class="doc_text">
1304 <p>This is not a directory in the normal llvm module; it is a separate
1306 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1308 module contains a comprehensive correctness, performance, and benchmarking
1310 suite for LLVM. It is a separate Subversion module because not every LLVM
1312 interested in downloading or building such a comprehensive test suite. For
1313 further details on this test suite, please see the
1314 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1317 <!-- ======================================================================= -->
1318 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1319 <div class="doc_text">
1321 <p>The <b>tools</b> directory contains the executables built out of the
1322 libraries above, which form the main part of the user interface. You can
1323 always get help for a tool by typing <tt>tool_name --help</tt>. The
1324 following is a brief introduction to the most important tools. More detailed
1325 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1329 <dt><tt><b>bugpoint</b></tt></dt>
1330 <dd><tt>bugpoint</tt> is used to debug
1331 optimization passes or code generation backends by narrowing down the
1332 given test case to the minimum number of passes and/or instructions that
1333 still cause a problem, whether it is a crash or miscompilation. See <a
1334 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1335 on using <tt>bugpoint</tt>.</dd>
1337 <dt><tt><b>llvmc</b></tt></dt>
1338 <dd>The LLVM Compiler Driver. This program can
1339 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1340 pre-processing, translation, optimization, assembly, and linking of programs
1341 all from one command line. <tt>llvmc</tt> also takes care of processing the
1342 dependent libraries found in bitcode. This reduces the need to get the
1343 traditional <tt>-l<name></tt> options right on the command line. Please
1344 note that this tool, while functional, is still experimental and not feature
1347 <dt><tt><b>llvm-ar</b></tt></dt>
1348 <dd>The archiver produces an archive containing
1349 the given LLVM bitcode files, optionally with an index for faster
1352 <dt><tt><b>llvm-as</b></tt></dt>
1353 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1356 <dt><tt><b>llvm-dis</b></tt></dt>
1357 <dd>The disassembler transforms the LLVM bitcode to human readable
1360 <dt><tt><b>llvm-ld</b></tt></dt>
1361 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1362 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1363 optimizations and allows optimization modules to be loaded and run so that
1364 language specific optimizations can be applied at link time.</dd>
1366 <dt><tt><b>llvm-link</b></tt></dt>
1367 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1368 a single program.</dd>
1370 <dt><tt><b>lli</b></tt></dt>
1371 <dd><tt>lli</tt> is the LLVM interpreter, which
1372 can directly execute LLVM bitcode (although very slowly...). For architectures
1373 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1374 will function as a Just-In-Time compiler (if the functionality was compiled
1375 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1377 <dt><tt><b>llc</b></tt></dt>
1378 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1379 translates LLVM bitcode to a native code assembly file or to C code (with
1380 the -march=c option).</dd>
1382 <dt><tt><b>llvm-gcc</b></tt></dt>
1383 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1384 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1385 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1386 usual machine code output. It works just like any other GCC compiler,
1387 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1388 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1389 separate Subversion module.</dd>
1391 <dt><tt><b>opt</b></tt></dt>
1392 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1393 transformations (which are specified on the command line), and then outputs
1394 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1395 get a list of the program transformations available in LLVM.<br>
1396 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1397 LLVM bitcode file and print out the results. It is primarily useful for
1398 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1402 <!-- ======================================================================= -->
1403 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1404 <div class="doc_text">
1406 <p>This directory contains utilities for working with LLVM source code, and some
1407 of the utilities are actually required as part of the build process because they
1408 are code generators for parts of LLVM infrastructure.</p>
1411 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1412 that finds differences between code that LLC generates and code that LLI
1413 generates. This is a useful tool if you are debugging one of them,
1414 assuming that the other generates correct output. For the full user
1415 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1417 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1418 syntax-highlighting files which will work with Emacs and XEmacs editors,
1419 providing syntax highlighting support for LLVM assembly files and TableGen
1420 description files. For information on how to use the syntax files, consult
1421 the <tt>README</tt> file in that directory.<br><br>
1423 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1424 and outputs all non-generated source files, which is useful if one wishes
1425 to do a lot of development across directories and does not want to
1426 individually find each file. One way to use it is to run, for example:
1427 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1430 <dt><tt><b>llvmgrep</b></tt></dt>
1431 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1432 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1433 line. This is a very efficient way of searching the source base for a
1434 particular regular expression.</dd>
1436 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1437 files in the current directory and then compiles and links the tool that
1438 is the first argument. For example, assuming you are in the directory
1439 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1440 simply running <tt>makellvm llc</tt> will make a build of the current
1441 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1442 causing a re-linking of LLC.<br><br>
1444 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1445 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1446 cron script to generate nightly status reports of the functionality of
1447 tools, and the results can be seen by following the appropriate link on
1448 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1450 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1451 the tool used to generate register descriptions, instruction set
1452 descriptions, and even assemblers from common TableGen description
1455 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1456 syntax-highlighting files which will work with the VIM editor, providing
1457 syntax highlighting support for LLVM assembly files and TableGen
1458 description files. For information on how to use the syntax files, consult
1459 the <tt>README</tt> file in that directory.<br><br>
1465 <!-- ======================================================================= -->
1466 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1467 <div class="doc_text">
1468 <p>This directory contains build scripts and project files for use with
1469 Visual C++. This allows developers on Windows to build LLVM without the need
1470 for Cygwin. The contents of this directory should be considered experimental
1474 <!-- *********************************************************************** -->
1475 <div class="doc_section">
1476 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1478 <!-- *********************************************************************** -->
1480 <div class="doc_text">
1481 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1482 so we only include instructions for llvm-gcc4.
1485 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1486 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1487 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1488 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1489 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1493 <!-- ======================================================================= -->
1494 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1496 <div class="doc_text">
1499 <li><p>First, create a simple C file, name it 'hello.c':</p>
1501 <div class="doc_code">
1503 #include <stdio.h>
1506 printf("hello world\n");
1511 <li><p>Next, compile the C file into a native executable:</p>
1513 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1515 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1516 -c arguments work as usual (producing a native .s or .o file,
1517 respectively).</p></li>
1519 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1521 <div class="doc_code">
1522 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1524 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1525 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1526 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1527 the bitcode file.</p>
1529 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1532 <li><p>Run the program in both forms. To run the program, use:</p>
1534 <div class="doc_code"><pre>% ./hello</pre></div>
1538 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1540 <p>The second examples shows how to invoke the LLVM JIT, <a
1541 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1543 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1546 <div class="doc_code">
1547 <pre>llvm-dis < hello.bc | less</pre>
1550 <li><p>Compile the program to native assembly using the LLC code
1553 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1555 <li><p>Assemble the native assembly language file into a program:</p>
1557 <div class="doc_code">
1559 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1561 <b>Others:</b> % gcc hello.s -o hello.native
1565 <li><p>Execute the native code program:</p>
1567 <div class="doc_code"><pre>% ./hello.native</pre></div>
1569 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1570 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1578 <!-- *********************************************************************** -->
1579 <div class="doc_section">
1580 <a name="problems">Common Problems</a>
1582 <!-- *********************************************************************** -->
1584 <div class="doc_text">
1586 <p>If you are having problems building or using LLVM, or if you have any other
1587 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1588 Asked Questions</a> page.</p>
1592 <!-- *********************************************************************** -->
1593 <div class="doc_section">
1594 <a name="links">Links</a>
1596 <!-- *********************************************************************** -->
1598 <div class="doc_text">
1600 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1601 some simple things... there are many more interesting and complicated things
1602 that you can do that aren't documented here (but we'll gladly accept a patch
1603 if you want to write something up!). For more information about LLVM, check
1607 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1608 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1609 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1610 that Uses LLVM</a></li>
1615 <!-- *********************************************************************** -->
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1624 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1625 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1626 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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