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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>,
256 <a href="#pf_11">11</a></sup></td>
257 <td>GCC 3.4.X, binutils 2.15</td>
261 <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,
262 <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td>
263 <td>GCC 3.4.X, binutils 2.15</td>
267 <p>LLVM has partial support for the following platforms:</p>
269 <table summary="LLVM partial platform support">
277 <td>x86<sup><a href="#pf_1">1</a></sup></td>
278 <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
280 <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
285 <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
291 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
296 <td>Linux<sup><a href="#pf_7">7</a></sup></td>
297 <td>Itanium (IA-64)</td>
301 <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
302 <td>Itanium (IA-64)</td>
309 <div class="doc_notes">
311 <li><a name="pf_1">Code generation supported for Pentium processors and
313 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
314 <li><a name="pf_3">No native code generation</a></li>
315 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
316 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
317 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
318 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
319 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
320 preventing LLVM from building correctly. Several workarounds have been
321 introduced into LLVM build system, but the bug can occur anytime in the
322 future. We highly recommend that you rebuild your current binutils with the
323 patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
324 Binutils bugzilla</a>, if it wasn't already applied.</li>
325 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
326 internal LLVM assert messages when compiled for Release at optimization
327 levels greater than 0 (i.e., <i>"-O1"</i> and higher).
328 Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
329 if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
330 <li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS
331 version of the perl package, and be sure it appears in your path
332 before any Windows-based versions such as Strawberry Perl and
333 ActivePerl, as these have Windows-specifics that will cause the
334 build to fail.</a></li>
335 <li><a name="pf_11">In general, LLVM modules requiring dynamic linking can
336 not be built on Windows. However, you can build LLVM tools using
337 <i>"make tools-only"</i>.</li>
341 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
342 mode, depending on the system (it is so large because of all the debugging
343 information and the fact that the libraries are statically linked into multiple
344 tools). If you do not need many of the tools and you are space-conscious, you
345 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make. The Release build
346 requires considerably less space.</p>
348 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
349 guaranteed to do so. If compilation is successful, the LLVM utilities should be
350 able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code
351 generation should work as well, although the generated native code may not work
352 on your platform.</p>
354 <p>The GCC front end is not very portable at the moment. If you want to get it
355 to work on another platform, you can download a copy of the source and <a
356 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
360 <!-- ======================================================================= -->
361 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
362 <div class="doc_text">
363 <p>Compiling LLVM requires that you have several software packages
364 installed. The table below lists those required packages. The Package column
365 is the usual name for the software package that LLVM depends on. The Version
366 column provides "known to work" versions of the package. The Notes column
367 describes how LLVM uses the package and provides other details.</p>
368 <table summary="Packages required to compile LLVM">
369 <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
372 <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
373 <td>3.79, 3.79.1</td>
374 <td>Makefile/build processor</td>
378 <td><a href="http://gcc.gnu.org">GCC</a></td>
380 <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
384 <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
386 <td>For building the CFE</td>
390 <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
392 <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
396 <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
398 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
402 <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
404 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
408 <td><a href="http://expect.nist.gov/">expect</a></td>
410 <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
414 <td><a href="http://www.perl.com/download.csp">perl</a></td>
416 <td>Nightly tester, utilities</td>
420 <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
422 <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
426 <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
428 <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
432 <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
434 <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
438 <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
440 <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
446 <div class="doc_notes">
448 <li><a name="sf1">Only the C and C++ languages are needed so there's no
449 need to build the other languages for LLVM's purposes.</a> See
450 <a href="#brokengcc">below</a> for specific version info.</li>
451 <li><a name="sf2">You only need Subversion if you intend to build from the
452 latest LLVM sources. If you're working from a release distribution, you
453 don't need Subversion.</a></li>
454 <li><a name="sf3">Only needed if you want to run the automated test
455 suite in the <tt>llvm/test</tt> directory.</a></li>
456 <li><a name="sf4">If you want to make changes to the configure scripts,
457 you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
458 or higher). You will also need automake (1.9.2). We only use aclocal
459 from that package.</a></li>
463 <p>Additionally, your compilation host is expected to have the usual
464 plethora of Unix utilities. Specifically:</p>
466 <li><b>ar</b> - archive library builder</li>
467 <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
468 <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
469 <li><b>chmod</b> - change permissions on a file</li>
470 <li><b>cat</b> - output concatenation utility</li>
471 <li><b>cp</b> - copy files</li>
472 <li><b>date</b> - print the current date/time </li>
473 <li><b>echo</b> - print to standard output</li>
474 <li><b>egrep</b> - extended regular expression search utility</li>
475 <li><b>find</b> - find files/dirs in a file system</li>
476 <li><b>grep</b> - regular expression search utility</li>
477 <li><b>gzip*</b> - gzip command for distribution generation</li>
478 <li><b>gunzip*</b> - gunzip command for distribution checking</li>
479 <li><b>install</b> - install directories/files </li>
480 <li><b>mkdir</b> - create a directory</li>
481 <li><b>mv</b> - move (rename) files</li>
482 <li><b>ranlib</b> - symbol table builder for archive libraries</li>
483 <li><b>rm</b> - remove (delete) files and directories</li>
484 <li><b>sed</b> - stream editor for transforming output</li>
485 <li><b>sh</b> - Bourne shell for make build scripts</li>
486 <li><b>tar</b> - tape archive for distribution generation</li>
487 <li><b>test</b> - test things in file system</li>
488 <li><b>unzip*</b> - unzip command for distribution checking</li>
489 <li><b>zip*</b> - zip command for distribution generation</li>
493 <!-- ======================================================================= -->
494 <div class="doc_subsection">
495 <a name="brokengcc">Broken versions of GCC and other tools</a>
498 <div class="doc_text">
500 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
501 bugs in the compiler. In particular, several versions of GCC crash when trying
502 to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
503 successfully with them (however, see important notes below). Other versions
504 of GCC will probably work as well. GCC versions listed
505 here are known to not work. If you are using one of these versions, please try
506 to upgrade your GCC to something more recent. If you run into a problem with a
507 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
508 us know</a>. Please use the "<tt>gcc -v</tt>" command to find out which version
509 of GCC you are using.
512 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
513 problems in the STL that effectively prevent it from compiling LLVM.
516 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
517 a bogus template error. This was fixed in later GCCs.</p>
519 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
520 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
521 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
523 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
524 Cygwin does not work. Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
525 to a newer version</a> if possible.</p>
526 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
527 possibly others) does not compile LLVM correctly (it appears that exception
528 handling is broken in some cases). Please download the FSF 3.3.3 or upgrade
529 to a newer version of GCC.</p>
530 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
531 code generator, causing an infinite loop in the llvm-gcc build when built
532 with optimizations enabled (i.e. a release build).</p>
533 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
534 code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0)
535 correctly compiles LLVM at -O2. A work around is to build release LLVM
536 builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
537 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
538 miscompiles portions of LLVM</a>.</p>
539 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
540 when building with optimizations enabled. It appears to work with
541 "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
543 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
545 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
546 default with ENABLE_OPTIMIZED=1. To work around this, build with
547 "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
548 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
549 compiling some files. At the time of this writing, GCC mainline (4.2)
550 did not share the problem.</p>
551 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
552 miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
553 code. LLVM will appear to mostly work but will be buggy, e.g. failing
554 portions of its testsuite.</p>
555 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
556 platforms compiling md5.c gets a mangled constant.</p>
557 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
558 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
559 about symbols remaining in the table on destruction.</p>
560 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
561 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
562 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
563 Users <a href="http://llvm.org/PR4145">reported</a> various problems related
564 with link errors when using this GCC version.</p>
565 <p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p>
566 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
567 when optimizations are turned on. The symptom is an infinite loop in
568 FoldingSetImpl::RemoveNode while running the code generator.</p>
569 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
570 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
571 defined in a discarded section. You can safely ignore these messages as they are
572 erroneous and the linkage is correct. These messages disappear using ld
575 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
576 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
577 causes huge link times (minutes instead of seconds) when building LLVM. We
578 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
580 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
581 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
582 which causes intermittent failures when building LLVM with position independent
583 code. The symptom is an error about cyclic dependencies. We recommend
584 upgrading to a newer version of Gold.</p>
590 <!-- *********************************************************************** -->
591 <div class="doc_section">
592 <a name="starting"><b>Getting Started with LLVM</b></a>
594 <!-- *********************************************************************** -->
596 <div class="doc_text">
598 <p>The remainder of this guide is meant to get you up and running with
599 LLVM and to give you some basic information about the LLVM environment.</p>
601 <p>The later sections of this guide describe the <a
602 href="#layout">general layout</a> of the the LLVM source tree, a <a
603 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
604 href="#links">links</a> to find more information about LLVM or to get
608 <!-- ======================================================================= -->
609 <div class="doc_subsection">
610 <a name="terminology">Terminology and Notation</a>
613 <div class="doc_text">
615 <p>Throughout this manual, the following names are used to denote paths
616 specific to the local system and working environment. <i>These are not
617 environment variables you need to set but just strings used in the rest
618 of this document below</i>. In any of the examples below, simply replace
619 each of these names with the appropriate pathname on your local system.
620 All these paths are absolute:</p>
625 This is the top level directory of the LLVM source tree.
630 This is the top level directory of the LLVM object tree (i.e. the
631 tree where object files and compiled programs will be placed. It
632 can be the same as SRC_ROOT).
637 This is where the LLVM GCC Front End is installed.
639 For the pre-built GCC front end binaries, the LLVMGCCDIR is
640 <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
645 <!-- ======================================================================= -->
646 <div class="doc_subsection">
647 <a name="environment">Setting Up Your Environment</a>
650 <div class="doc_text">
653 In order to compile and use LLVM, you may need to set some environment
657 <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
658 <dd>[Optional] This environment variable helps LLVM linking tools find the
659 locations of your bitcode libraries. It is provided only as a
660 convenience since you can specify the paths using the -L options of the
661 tools and the C/C++ front-end will automatically use the bitcode files
663 <tt>lib</tt> directory.</dd>
668 <!-- ======================================================================= -->
669 <div class="doc_subsection">
670 <a name="unpack">Unpacking the LLVM Archives</a>
673 <div class="doc_text">
676 If you have the LLVM distribution, you will need to unpack it before you
677 can begin to compile it. LLVM is distributed as a set of two files: the LLVM
678 suite and the LLVM GCC front end compiled for your platform. There is an
679 additional test suite that is optional. Each file is a TAR archive that is
680 compressed with the gzip program.
683 <p>The files are as follows, with <em>x.y</em> marking the version number:
685 <dt><tt>llvm-x.y.tar.gz</tt></dt>
686 <dd>Source release for the LLVM libraries and tools.<br></dd>
688 <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
689 <dd>Source release for the LLVM test suite.</dd>
691 <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
692 <dd>Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root
693 directory for build instructions.<br></dd>
695 <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
696 <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
702 <!-- ======================================================================= -->
703 <div class="doc_subsection">
704 <a name="checkout">Checkout LLVM from Subversion</a>
707 <div class="doc_text">
709 <p>If you have access to our Subversion repository, you can get a fresh copy of
710 the entire source code. All you need to do is check it out from Subversion as
714 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
715 <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
716 <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
721 <p>This will create an '<tt>llvm</tt>' directory in the current
722 directory and fully populate it with the LLVM source code, Makefiles,
723 test directories, and local copies of documentation files.</p>
725 <p>If you want to get a specific release (as opposed to the most recent
726 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
727 '<tt>trunk</tt>'). The following releases are located in the following
728 subdirectories of the '<tt>tags</tt>' directory:</p>
731 <li>Release 2.6: <b>RELEASE_26</b></li>
732 <li>Release 2.5: <b>RELEASE_25</b></li>
733 <li>Release 2.4: <b>RELEASE_24</b></li>
734 <li>Release 2.3: <b>RELEASE_23</b></li>
735 <li>Release 2.2: <b>RELEASE_22</b></li>
736 <li>Release 2.1: <b>RELEASE_21</b></li>
737 <li>Release 2.0: <b>RELEASE_20</b></li>
738 <li>Release 1.9: <b>RELEASE_19</b></li>
739 <li>Release 1.8: <b>RELEASE_18</b></li>
740 <li>Release 1.7: <b>RELEASE_17</b></li>
741 <li>Release 1.6: <b>RELEASE_16</b></li>
742 <li>Release 1.5: <b>RELEASE_15</b></li>
743 <li>Release 1.4: <b>RELEASE_14</b></li>
744 <li>Release 1.3: <b>RELEASE_13</b></li>
745 <li>Release 1.2: <b>RELEASE_12</b></li>
746 <li>Release 1.1: <b>RELEASE_11</b></li>
747 <li>Release 1.0: <b>RELEASE_1</b></li>
750 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
751 you get it from the Subversion repository:</p>
753 <div class="doc_code">
756 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
760 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
761 configured by the LLVM configure script as well as automatically updated when
762 you run <tt>svn update</tt>.</p>
764 <p>If you would like to get the GCC front end source code, you can also get it
765 and build it yourself. Please follow <a href="GCCFEBuildInstrs.html">these
766 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
770 <!-- ======================================================================= -->
771 <div class="doc_subsection">
772 <a name="installcf">Install the GCC Front End</a>
775 <div class="doc_text">
777 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
778 LLVM GCC front end from the binary distribution. It is used for running the
779 llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally
780 <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
781 main LLVM repository.</p>
783 <p>To install the GCC front end, do the following:</p>
786 <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
787 <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
791 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
792 llvm-g++ to some directory in your path. When you configure LLVM, it will
793 automatically detect llvm-gcc's presence (if it is in your path) enabling its
794 use in llvm-test. Note that you can always build or install llvm-gcc at any
795 pointer after building the main LLVM repository: just reconfigure llvm and
796 llvm-test will pick it up.
799 <p>The binary versions of the GCC front end may not suit all of your needs. For
800 example, the binary distribution may include an old version of a system header
801 file, not "fix" a header file that needs to be fixed for GCC, or it may be
802 linked with libraries not available on your system.</p>
804 <p>In cases like these, you may want to try <a
805 href="GCCFEBuildInstrs.html">building the GCC front end from source.</a> This is
806 much easier now than it was in the past.</p>
810 <!-- ======================================================================= -->
811 <div class="doc_subsection">
812 <a name="config">Local LLVM Configuration</a>
815 <div class="doc_text">
817 <p>Once checked out from the Subversion repository, the LLVM suite source
819 configured via the <tt>configure</tt> script. This script sets variables in the
820 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
821 <tt>llvm/include/Config/config.h</tt>. It also populates <i>OBJ_ROOT</i> with
822 the Makefiles needed to begin building LLVM.</p>
824 <p>The following environment variables are used by the <tt>configure</tt>
825 script to configure the build system:</p>
827 <table summary="LLVM configure script environment variables">
828 <tr><th>Variable</th><th>Purpose</th></tr>
831 <td>Tells <tt>configure</tt> which C compiler to use. By default,
832 <tt>configure</tt> will look for the first GCC C compiler in
833 <tt>PATH</tt>. Use this variable to override
834 <tt>configure</tt>'s default behavior.</td>
838 <td>Tells <tt>configure</tt> which C++ compiler to use. By default,
839 <tt>configure</tt> will look for the first GCC C++ compiler in
840 <tt>PATH</tt>. Use this variable to override
841 <tt>configure</tt>'s default behavior.</td>
845 <p>The following options can be used to set or enable LLVM specific options:</p>
848 <dt><i>--with-llvmgccdir</i></dt>
849 <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
850 The value of this option should specify the full pathname of the C/C++ Front
851 End to be used. If this option is not provided, the PATH will be searched for
852 a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
853 be inferred from the path found. If the option is not given, and no llvm-gcc
854 can be found in the path then a warning will be produced by
855 <tt>configure</tt> indicating this situation. LLVM may still be built with
856 the <tt>tools-only</tt> target but attempting to build the runtime libraries
857 will fail as these libraries require llvm-gcc and llvm-g++. See
858 <a href="#installcf">Install the GCC Front End</a> for details on installing
859 the C/C++ Front End. See
860 <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
861 for details on building the C/C++ Front End.</dd>
862 <dt><i>--with-tclinclude</i></dt>
863 <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
864 found. Use this if you have multiple tcl installations on your machine and you
865 want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
866 dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
867 option, the LLVM configure script will search for the tcl 8.4 and 8.3
871 <dt><i>--enable-optimized</i></dt>
873 Enables optimized compilation (debugging symbols are removed
874 and GCC optimization flags are enabled). Note that this is the default
875 setting if you are using the LLVM distribution. The default behavior
876 of an Subversion checkout is to use an unoptimized build (also known as a
880 <dt><i>--enable-debug-runtime</i></dt>
882 Enables debug symbols in the runtime libraries. The default is to strip
883 debug symbols from the runtime libraries.
885 <dt><i>--enable-jit</i></dt>
887 Compile the Just In Time (JIT) compiler functionality. This is not
889 on all platforms. The default is dependent on platform, so it is best
890 to explicitly enable it if you want it.
893 <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
894 <dd>Controls which targets will be built and linked into llc. The default
895 value for <tt>target_options</tt> is "all" which builds and links all
896 available targets. The value "host-only" can be specified to build only a
897 native compiler (no cross-compiler targets available). The "native" target is
898 selected as the target of the build host. You can also specify a comma
899 separated list of target names that you want available in llc. The target
900 names use all lower case. The current set of targets is: <br>
901 <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
903 <dt><i>--enable-doxygen</i></dt>
904 <dd>Look for the doxygen program and enable construction of doxygen based
905 documentation from the source code. This is disabled by default because
906 generating the documentation can take a long time and producess 100s of
907 megabytes of output.</dd>
908 <dt><i>--with-udis86</i></dt>
909 <dd>LLVM can use external disassembler library for various purposes (now it's
910 used only for examining code produced by JIT). This option will enable usage
911 of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
912 bits) disassembler library.</dd>
915 <p>To configure LLVM, follow these steps:</p>
918 <li><p>Change directory into the object root directory:</p>
920 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
922 <li><p>Run the <tt>configure</tt> script located in the LLVM source
925 <div class="doc_code">
926 <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
932 <!-- ======================================================================= -->
933 <div class="doc_subsection">
934 <a name="compile">Compiling the LLVM Suite Source Code</a>
937 <div class="doc_text">
939 <p>Once you have configured LLVM, you can build it. There are three types of
945 These builds are the default when one is using an Subversion checkout and
946 types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
947 used during configuration). The build system will compile the tools and
948 libraries with debugging information. To get a Debug Build using the
949 LLVM distribution the <tt>--disable-optimized</tt> option must be passed
950 to <tt>configure</tt>.
953 <dt>Release (Optimized) Builds
955 These builds are enabled with the <tt>--enable-optimized</tt> option to
956 <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
957 <tt>gmake</tt> command line. For these builds, the build system will
958 compile the tools and libraries with GCC optimizations enabled and strip
959 debugging information from the libraries and executables it generates.
960 Note that Release Builds are default when using an LLVM distribution.
965 These builds are for use with profiling. They compile profiling
966 information into the code for use with programs like <tt>gprof</tt>.
967 Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
968 on the <tt>gmake</tt> command line.
971 <p>Once you have LLVM configured, you can build it by entering the
972 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
974 <div class="doc_code"><pre>% gmake</pre></div>
976 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
977 are using a version of GCC that is known not to compile LLVM.</p>
980 If you have multiple processors in your machine, you may wish to use some of
981 the parallel build options provided by GNU Make. For example, you could use the
984 <div class="doc_code"><pre>% gmake -j2</pre></div>
986 <p>There are several special targets which are useful when working with the LLVM
990 <dt><tt>gmake clean</tt>
992 Removes all files generated by the build. This includes object files,
993 generated C/C++ files, libraries, and executables.
996 <dt><tt>gmake dist-clean</tt>
998 Removes everything that <tt>gmake clean</tt> does, but also removes files
999 generated by <tt>configure</tt>. It attempts to return the source tree to the
1000 original state in which it was shipped.
1003 <dt><tt>gmake install</tt>
1005 Installs LLVM header files, libraries, tools, and documentation in a
1007 under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
1008 defaults to <tt>/usr/local</tt>.
1011 <dt><tt>gmake -C runtime install-bytecode</tt>
1013 Assuming you built LLVM into $OBJDIR, when this command is run, it will
1014 install bitcode libraries into the GCC front end's bitcode library
1015 directory. If you need to update your bitcode libraries,
1016 this is the target to use once you've built them.
1020 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1021 details on these <tt>make</tt> targets and descriptions of other targets
1024 <p>It is also possible to override default values from <tt>configure</tt> by
1025 declaring variables on the command line. The following are some examples:</p>
1028 <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1030 Perform a Release (Optimized) build.
1033 <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1035 Perform a Release (Optimized) build without assertions enabled.
1038 <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1040 Perform a Debug build.
1043 <dt><tt>gmake ENABLE_PROFILING=1</tt>
1045 Perform a Profiling build.
1048 <dt><tt>gmake VERBOSE=1</tt>
1050 Print what <tt>gmake</tt> is doing on standard output.
1053 <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1054 <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1055 the standard output. This also implies <tt>VERBOSE=1</tt>.
1059 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1060 it and any subdirectories that it contains. Entering any directory inside the
1061 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1062 that directory that is out of date.</p>
1066 <!-- ======================================================================= -->
1067 <div class="doc_subsection">
1068 <a name="cross-compile">Cross-Compiling LLVM</a>
1071 <div class="doc_text">
1072 <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1073 executables and libraries to be hosted on a platform different from the
1074 platform where they are build (a Canadian Cross build). To configure a
1075 cross-compile, supply the configure script with <tt>--build</tt> and
1076 <tt>--host</tt> options that are different. The values of these options must
1077 be legal target triples that your GCC compiler supports.</p>
1079 <p>The result of such a build is executables that are not runnable on
1080 on the build host (--build option) but can be executed on the compile host
1081 (--host option).</p>
1084 <!-- ======================================================================= -->
1085 <div class="doc_subsection">
1086 <a name="objfiles">The Location of LLVM Object Files</a>
1089 <div class="doc_text">
1091 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1092 several LLVM builds. Hence, it is possible to build LLVM for several different
1093 platforms or configurations using the same source tree.</p>
1095 <p>This is accomplished in the typical autoconf manner:</p>
1098 <li><p>Change directory to where the LLVM object files should live:</p>
1100 <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1102 <li><p>Run the <tt>configure</tt> script found in the LLVM source
1105 <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1108 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1109 named after the build type:</p>
1116 <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1118 <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1126 <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1128 <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1136 <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1138 <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1144 <!-- ======================================================================= -->
1145 <div class="doc_subsection">
1146 <a name="optionalconfig">Optional Configuration Items</a>
1149 <div class="doc_text">
1152 If you're running on a Linux system that supports the "<a
1153 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1154 module, and you have root access on the system, you can set your system up to
1155 execute LLVM bitcode files directly. To do this, use commands like this (the
1156 first command may not be required if you are already using the module):</p>
1158 <div class="doc_code">
1160 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1161 $ echo ':llvm:M::BC::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
1162 $ chmod u+x hello.bc (if needed)
1168 This allows you to execute LLVM bitcode files directly. Thanks to Jack
1169 Cummings for pointing this out!
1175 <!-- *********************************************************************** -->
1176 <div class="doc_section">
1177 <a name="layout"><b>Program Layout</b></a>
1179 <!-- *********************************************************************** -->
1181 <div class="doc_text">
1183 <p>One useful source of information about the LLVM source base is the LLVM <a
1184 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1185 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1186 The following is a brief introduction to code layout:</p>
1190 <!-- ======================================================================= -->
1191 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1192 <div class="doc_text">
1193 <p>This directory contains some simple examples of how to use the LLVM IR and
1197 <!-- ======================================================================= -->
1198 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1199 <div class="doc_text">
1201 <p>This directory contains public header files exported from the LLVM
1202 library. The three main subdirectories of this directory are:</p>
1205 <dt><tt><b>llvm/include/llvm</b></tt></dt>
1206 <dd>This directory contains all of the LLVM specific header files. This
1207 directory also has subdirectories for different portions of LLVM:
1208 <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1211 <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1212 <dd>This directory contains generic support libraries that are provided with
1213 LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1214 and a Command Line option processing library store their header files here.
1217 <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1218 <dd>This directory contains header files configured by the <tt>configure</tt>
1219 script. They wrap "standard" UNIX and C header files. Source code can
1220 include these header files which automatically take care of the conditional
1221 #includes that the <tt>configure</tt> script generates.</dd>
1225 <!-- ======================================================================= -->
1226 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1227 <div class="doc_text">
1229 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1230 almost all code exists in libraries, making it very easy to share code among the
1231 different <a href="#tools">tools</a>.</p>
1234 <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1235 <dd> This directory holds the core LLVM source files that implement core
1236 classes like Instruction and BasicBlock.</dd>
1238 <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1239 <dd>This directory holds the source code for the LLVM assembly language parser
1242 <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1243 <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1245 <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1246 different program analyses, such as Dominator Information, Call Graphs,
1247 Induction Variables, Interval Identification, Natural Loop Identification,
1250 <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1251 <dd> This directory contains the source code for the LLVM to LLVM program
1252 transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1253 Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1254 Elimination, and many others.</dd>
1256 <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1257 <dd> This directory contains files that describe various target architectures
1258 for code generation. For example, the <tt>llvm/lib/Target/X86</tt>
1259 directory holds the X86 machine description while
1260 <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1262 <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1263 <dd> This directory contains the major parts of the code generator: Instruction
1264 Selector, Instruction Scheduling, and Register Allocation.</dd>
1266 <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1267 <dd> This directory contains the source level debugger library that makes
1268 it possible to instrument LLVM programs so that a debugger could identify
1269 source code locations at which the program is executing.</dd>
1271 <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1272 <dd> This directory contains libraries for executing LLVM bitcode directly
1273 at runtime in both interpreted and JIT compiled fashions.</dd>
1275 <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1276 <dd> This directory contains the source code that corresponds to the header
1277 files located in <tt>llvm/include/Support/</tt>.</dd>
1279 <dt><tt><b>llvm/lib/System/</b></tt></dt>
1280 <dd>This directory contains the operating system abstraction layer that
1281 shields LLVM from platform-specific coding.</dd>
1286 <!-- ======================================================================= -->
1287 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1288 <div class="doc_text">
1289 <p>This directory contains projects that are not strictly part of LLVM but are
1290 shipped with LLVM. This is also the directory where you should create your own
1291 LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1292 to set up your own project.</p>
1295 <!-- ======================================================================= -->
1296 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1297 <div class="doc_text">
1299 <p>This directory contains libraries which are compiled into LLVM bitcode and
1300 used when linking programs with the GCC front end. Most of these libraries are
1301 skeleton versions of real libraries; for example, libc is a stripped down
1302 version of glibc.</p>
1304 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1309 <!-- ======================================================================= -->
1310 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1311 <div class="doc_text">
1312 <p>This directory contains feature and regression tests and other basic sanity
1313 checks on the LLVM infrastructure. These are intended to run quickly and cover
1314 a lot of territory without being exhaustive.</p>
1317 <!-- ======================================================================= -->
1318 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1319 <div class="doc_text">
1320 <p>This is not a directory in the normal llvm module; it is a separate
1322 module that must be checked out (usually to <tt>projects/test-suite</tt>).
1324 module contains a comprehensive correctness, performance, and benchmarking
1326 suite for LLVM. It is a separate Subversion module because not every LLVM
1328 interested in downloading or building such a comprehensive test suite. For
1329 further details on this test suite, please see the
1330 <a href="TestingGuide.html">Testing Guide</a> document.</p>
1333 <!-- ======================================================================= -->
1334 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1335 <div class="doc_text">
1337 <p>The <b>tools</b> directory contains the executables built out of the
1338 libraries above, which form the main part of the user interface. You can
1339 always get help for a tool by typing <tt>tool_name --help</tt>. The
1340 following is a brief introduction to the most important tools. More detailed
1341 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1345 <dt><tt><b>bugpoint</b></tt></dt>
1346 <dd><tt>bugpoint</tt> is used to debug
1347 optimization passes or code generation backends by narrowing down the
1348 given test case to the minimum number of passes and/or instructions that
1349 still cause a problem, whether it is a crash or miscompilation. See <a
1350 href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1351 on using <tt>bugpoint</tt>.</dd>
1353 <dt><tt><b>llvmc</b></tt></dt>
1354 <dd>The LLVM Compiler Driver. This program can
1355 be configured to utilize both LLVM and non-LLVM compilation tools to enable
1356 pre-processing, translation, optimization, assembly, and linking of programs
1357 all from one command line. <tt>llvmc</tt> also takes care of processing the
1358 dependent libraries found in bitcode. This reduces the need to get the
1359 traditional <tt>-l<name></tt> options right on the command line. Please
1360 note that this tool, while functional, is still experimental and not feature
1363 <dt><tt><b>llvm-ar</b></tt></dt>
1364 <dd>The archiver produces an archive containing
1365 the given LLVM bitcode files, optionally with an index for faster
1368 <dt><tt><b>llvm-as</b></tt></dt>
1369 <dd>The assembler transforms the human readable LLVM assembly to LLVM
1372 <dt><tt><b>llvm-dis</b></tt></dt>
1373 <dd>The disassembler transforms the LLVM bitcode to human readable
1376 <dt><tt><b>llvm-ld</b></tt></dt>
1377 <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1378 This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1379 optimizations and allows optimization modules to be loaded and run so that
1380 language specific optimizations can be applied at link time.</dd>
1382 <dt><tt><b>llvm-link</b></tt></dt>
1383 <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1384 a single program.</dd>
1386 <dt><tt><b>lli</b></tt></dt>
1387 <dd><tt>lli</tt> is the LLVM interpreter, which
1388 can directly execute LLVM bitcode (although very slowly...). For architectures
1389 that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1390 will function as a Just-In-Time compiler (if the functionality was compiled
1391 in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1393 <dt><tt><b>llc</b></tt></dt>
1394 <dd> <tt>llc</tt> is the LLVM backend compiler, which
1395 translates LLVM bitcode to a native code assembly file or to C code (with
1396 the -march=c option).</dd>
1398 <dt><tt><b>llvm-gcc</b></tt></dt>
1399 <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1400 use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1401 bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1402 usual machine code output. It works just like any other GCC compiler,
1403 taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1404 Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1405 separate Subversion module.</dd>
1407 <dt><tt><b>opt</b></tt></dt>
1408 <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1409 transformations (which are specified on the command line), and then outputs
1410 the resultant bitcode. The '<tt>opt --help</tt>' command is a good way to
1411 get a list of the program transformations available in LLVM.<br>
1412 <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1413 LLVM bitcode file and print out the results. It is primarily useful for
1414 debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1418 <!-- ======================================================================= -->
1419 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1420 <div class="doc_text">
1422 <p>This directory contains utilities for working with LLVM source code, and some
1423 of the utilities are actually required as part of the build process because they
1424 are code generators for parts of LLVM infrastructure.</p>
1427 <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1428 that finds differences between code that LLC generates and code that LLI
1429 generates. This is a useful tool if you are debugging one of them,
1430 assuming that the other generates correct output. For the full user
1431 manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1433 <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1434 syntax-highlighting files which will work with Emacs and XEmacs editors,
1435 providing syntax highlighting support for LLVM assembly files and TableGen
1436 description files. For information on how to use the syntax files, consult
1437 the <tt>README</tt> file in that directory.<br><br>
1439 <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1440 and outputs all non-generated source files, which is useful if one wishes
1441 to do a lot of development across directories and does not want to
1442 individually find each file. One way to use it is to run, for example:
1443 <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1446 <dt><tt><b>llvmgrep</b></tt></dt>
1447 <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1448 passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1449 line. This is a very efficient way of searching the source base for a
1450 particular regular expression.</dd>
1452 <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1453 files in the current directory and then compiles and links the tool that
1454 is the first argument. For example, assuming you are in the directory
1455 <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1456 simply running <tt>makellvm llc</tt> will make a build of the current
1457 directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1458 causing a re-linking of LLC.<br><br>
1460 <dt><tt><b>NewNightlyTest.pl</b></tt> and
1461 <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1462 cron script to generate nightly status reports of the functionality of
1463 tools, and the results can be seen by following the appropriate link on
1464 the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1466 <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1467 the tool used to generate register descriptions, instruction set
1468 descriptions, and even assemblers from common TableGen description
1471 <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1472 syntax-highlighting files which will work with the VIM editor, providing
1473 syntax highlighting support for LLVM assembly files and TableGen
1474 description files. For information on how to use the syntax files, consult
1475 the <tt>README</tt> file in that directory.<br><br>
1481 <!-- ======================================================================= -->
1482 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1483 <div class="doc_text">
1484 <p>This directory contains build scripts and project files for use with
1485 Visual C++. This allows developers on Windows to build LLVM without the need
1486 for Cygwin. The contents of this directory should be considered experimental
1490 <!-- *********************************************************************** -->
1491 <div class="doc_section">
1492 <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1494 <!-- *********************************************************************** -->
1496 <div class="doc_text">
1497 <p>This section gives an example of using LLVM. llvm-gcc3 is now obsolete,
1498 so we only include instructions for llvm-gcc4.
1501 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1502 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1503 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1504 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1505 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1509 <!-- ======================================================================= -->
1510 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1512 <div class="doc_text">
1515 <li><p>First, create a simple C file, name it 'hello.c':</p>
1517 <div class="doc_code">
1519 #include <stdio.h>
1522 printf("hello world\n");
1527 <li><p>Next, compile the C file into a native executable:</p>
1529 <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1531 <p>Note that llvm-gcc works just like GCC by default. The standard -S and
1532 -c arguments work as usual (producing a native .s or .o file,
1533 respectively).</p></li>
1535 <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1537 <div class="doc_code">
1538 <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1540 <p>The -emit-llvm option can be used with the -S or -c options to emit an
1541 LLVM ".ll" or ".bc" file (respectively) for the code. This allows you
1542 to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1543 the bitcode file.</p>
1545 <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1548 <li><p>Run the program in both forms. To run the program, use:</p>
1550 <div class="doc_code"><pre>% ./hello</pre></div>
1554 <div class="doc_code"><pre>% lli hello.bc</pre></div>
1556 <p>The second examples shows how to invoke the LLVM JIT, <a
1557 href="CommandGuide/html/lli.html">lli</a>.</p></li>
1559 <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1562 <div class="doc_code">
1563 <pre>llvm-dis < hello.bc | less</pre>
1566 <li><p>Compile the program to native assembly using the LLC code
1569 <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1571 <li><p>Assemble the native assembly language file into a program:</p>
1573 <div class="doc_code">
1575 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1577 <b>Others:</b> % gcc hello.s -o hello.native
1581 <li><p>Execute the native code program:</p>
1583 <div class="doc_code"><pre>% ./hello.native</pre></div>
1585 <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1586 the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1594 <!-- *********************************************************************** -->
1595 <div class="doc_section">
1596 <a name="problems">Common Problems</a>
1598 <!-- *********************************************************************** -->
1600 <div class="doc_text">
1602 <p>If you are having problems building or using LLVM, or if you have any other
1603 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1604 Asked Questions</a> page.</p>
1608 <!-- *********************************************************************** -->
1609 <div class="doc_section">
1610 <a name="links">Links</a>
1612 <!-- *********************************************************************** -->
1614 <div class="doc_text">
1616 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1617 some simple things... there are many more interesting and complicated things
1618 that you can do that aren't documented here (but we'll gladly accept a patch
1619 if you want to write something up!). For more information about LLVM, check
1623 <li><a href="http://llvm.org/">LLVM homepage</a></li>
1624 <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1625 <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1626 that Uses LLVM</a></li>
1631 <!-- *********************************************************************** -->
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1640 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1641 <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1642 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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