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  11 <div class="doc_title">
  12   Getting Started with the LLVM System
  13 </div>
  14
  15 <ul>
  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>
  19     <ol>
  20       <li><a href="#hardware">Hardware</a>
  21       <li><a href="#software">Software</a>
  22       <li><a href="#brokengcc">Broken versions of GCC and other tools</a>
  23     </ol></li>
  24
  25   <li><a href="#starting">Getting Started with LLVM</a>
  26     <ol>
  27       <li><a href="#terminology">Terminology and Notation</a>
  28       <li><a href="#environment">Setting Up Your Environment</a>
  29       <li><a href="#unpack">Unpacking the LLVM Archives</a>
  30       <li><a href="#checkout">Checkout LLVM from Subversion</a>
  31       <li><a href="#installcf">Install the GCC Front End</a>
  32       <li><a href="#config">Local LLVM Configuration</a>
  33       <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
  34       <li><a href="#cross-compile">Cross-Compiling LLVM</a>
  35       <li><a href="#objfiles">The Location of LLVM Object Files</a>
  36       <li><a href="#optionalconfig">Optional Configuration Items</a>
  37     </ol></li>
  38
  39   <li><a href="#layout">Program layout</a>
  40     <ol>
  41       <li><a href="#examples"><tt>llvm/examples</tt></a>
  42       <li><a href="#include"><tt>llvm/include</tt></a>
  43       <li><a href="#lib"><tt>llvm/lib</tt></a>
  44       <li><a href="#projects"><tt>llvm/projects</tt></a>
  45       <li><a href="#runtime"><tt>llvm/runtime</tt></a>
  46       <li><a href="#test"><tt>llvm/test</tt></a>
  47       <li><a href="#llvmtest"><tt>llvm-test</tt></a>
  48       <li><a href="#tools"><tt>llvm/tools</tt></a>
  49       <li><a href="#utils"><tt>llvm/utils</tt></a>
  50       <li><a href="#win32"><tt>llvm/win32</tt></a>
  51     </ol></li>
  52
  53   <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
  54       <ol>
  55          <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
  56       </ol>
  57   <li><a href="#problems">Common Problems</a>
  58   <li><a href="#links">Links</a>
  59 </ul>
  60
  61 <div class="doc_author">
  62   <p>Written by:
  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>.
  68   </p>
  69 </div>
  70
  71
  72 <!-- *********************************************************************** -->
  73 <div class="doc_section">
  74   <a name="overview"><b>Overview</b></a>
  75 </div>
  76 <!-- *********************************************************************** -->
  77
  78 <div class="doc_text">
  79
  80 <p>Welcome to LLVM! In order to get started, you first need to know some
  81 basic information.</p>
  82
  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>
  88
  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>
  94
  95 <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
  98 and performance.
  99 </p>
 100
 101 </div>
 102
 103 <!-- *********************************************************************** -->
 104 <div class="doc_section">
 105   <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
 106 </div>
 107 <!-- *********************************************************************** -->
 108
 109 <div class="doc_text">
 110
 111 <p>Here's the short story for getting up and running quickly with LLVM:</p>
 112
 113 <ol>
 114   <li>Read the documentation.</li>
 115   <li>Read the documentation.</li>
 116   <li>Remember that you were warned twice about reading the documentation.</li>
 117   <li>Install the GCC front end if you intend to compile C or C++:
 118     <ol>
 119       <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
 120       <li><tt>gunzip --stdout llvm-gcc.<i>platform</i>.tar.gz | tar -xvf -</tt>
 121       </li>
 122       <li><tt>cd llvm-gcc3.4/<i>platform</i> (llvm-gcc3.4 only)<br>
 123         ./fixheaders</tt></li>
 124       <li>Add llvm-gcc's "bin" directory to your PATH variable.</li>
 125     </ol></li>
 126
 127   <li>Get the LLVM Source Code
 128   <ul>
 129     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 130     <ol>
 131       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 132       <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
 133     </ol></li>
 134
 135   </ul></li>
 136
 137   <li><b>[Optional]</b> Get the Test Suite Source Code
 138   <ul>
 139     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 140     <ol>
 141       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 142       <li><tt>cd llvm/projects</tt>
 143       <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
 144     </ol></li>
 145
 146   </ul></li>
 147
 148
 149   <li>Configure the LLVM Build Environment
 150   <ol>
 151     <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
 152     <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
 153     Some common options:
 154
 155       <ul>
 156         <li><tt>--prefix=<i>directory</i></tt>
 157         <p>Specify for <i>directory</i> the full pathname of where you
 158         want the LLVM tools and libraries to be installed (default
 159         <tt>/usr/local</tt>).</p></li>
 160         <li><tt>--with-llvmgccdir=<i>directory</i></tt>
 161         <p>Optionally, specify for <i>directory</i> the full pathname of the
 162         C/C++ front end installation to use with this LLVM configuration. If
 163         not specified, the PATH will be searched.</p></li>
 164         <li><tt>--enable-spec2000=<i>directory</i></tt>
 165             <p>Enable the SPEC2000 benchmarks for testing.  The SPEC2000
 166             benchmarks should be available in
 167             <tt><i>directory</i></tt>.</p></li>
 168       </ul>
 169   </ol></li>
 170
 171   <li>Build the LLVM Suite:
 172   <ol>
 173       <li><tt>gmake -k |&amp; tee gnumake.out
 174       &nbsp;&nbsp;&nbsp;# 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>
 177   </ol>
 178
 179 </ol>
 180
 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>
 186
 187 </div>
 188
 189 <!-- *********************************************************************** -->
 190 <div class="doc_section">
 191   <a name="requirements"><b>Requirements</b></a>
 192 </div>
 193 <!-- *********************************************************************** -->
 194
 195 <div class="doc_text">
 196
 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>
 200
 201 </div>
 202
 203 <!-- ======================================================================= -->
 204 <div class="doc_subsection">
 205   <a name="hardware"><b>Hardware</b></a>
 206 </div>
 207
 208 <div class="doc_text">
 209
 210 <p>LLVM is known to work on the following platforms:</p>
 211
 212 <table cellpadding="3" summary="Known LLVM platforms">
 213 <tr>
 214   <th>OS</th>
 215   <th>Arch</th>
 216   <th>Compilers</th>
 217 </tr>
 218 <tr>
 219   <td>Linux</td>
 220   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 221   <td>GCC</td>
 222 </tr>
 223 <tr>
 224   <td>Solaris</td>
 225   <td>V9 (Ultrasparc)</td>
 226   <td>GCC</td>
 227 </tr>
 228 <tr>
 229   <td>FreeBSD</td>
 230   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 231   <td>GCC</td>
 232 </tr>
 233 <tr>
 234   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 235   <td>PowerPC</td>
 236   <td>GCC</td>
 237 </tr>
 238 <tr>
 239   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 240   <td>x86</td>
 241   <td>GCC</td>
 242
 243 </tr>
 244 <tr>
 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>
 248 </tr>
 249 <tr>
 250   <td>MinGW/Win32</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>
 253 </tr>
 254 <tr>
 255   <td>Linux</td>
 256   <td>amd64<sup><a href="#pf_3">3</a></sup></td>
 257   <td>GCC</td>
 258 </tr>
 259 </table>
 260
 261 <p>LLVM has partial support for the following platforms:</p>
 262
 263 <table summary="LLVM partial platform support">
 264 <tr>
 265   <th>OS</th>
 266   <th>Arch</th>
 267   <th>Compilers</th>
 268 </tr>
 269 <tr>
 270   <td>Windows</td>
 271   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 272   <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
 273 <tr>
 274   <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
 275   <td>PowerPC</td>
 276   <td>GCC</td>
 277 </tr>
 278 <tr>
 279   <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
 280   <td>PowerPC</td>
 281   <td>GCC</td>
 282 </tr>
 283
 284 <tr>
 285   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 286   <td>Alpha</td>
 287   <td>GCC</td>
 288 </tr>
 289 <tr>
 290   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 291   <td>Itanium (IA-64)</td>
 292   <td>GCC</td>
 293 </tr>
 294 <tr>
 295   <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
 296   <td>Itanium (IA-64)</td>
 297   <td>HP aCC</td>
 298 </tr>
 299 </table>
 300
 301 <p><b>Notes:</b></p>
 302
 303 <div class="doc_notes">
 304 <ol>
 305 <li><a name="pf_1">Code generation supported for Pentium processors and
 306 up</a></li>
 307 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
 308 <li><a name="pf_3">No native code generation</a></li>
 309 <li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
 310 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
 311 <li><a name="pf_6">The port is done using the MSYS shell.</a>
 312 <a href="http://www.mingw.org/MinGWiki/">Download</a> and install
 313 bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source,
 314 if necessary. Bison &amp; flex can be also grabbed from GNUWin32 sf.net
 315 project.</li>
 316 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
 317 <li><a name="pf_8">Binutils</a> up to post-2.17 has bug in bfd/cofflink.c
 318     preventing LLVM from building correctly. Several workarounds have been
 319     introduced into LLVM build system, but the bug can occur anytime in the
 320     future. We highly recommend that you rebuild your current binutils with the
 321     patch from <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=2659">
 322     Binutils bugzilla</a>, if it wasn't already applied.</li>
 323 </ol>
 324 </div>
 325
 326 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
 327 mode, depending on the system (it is so large because of all the debugging
 328 information and the fact that the libraries are statically linked into multiple
 329 tools).  If you do not need many of the tools and you are space-conscious,
 330 you can disable them individually in <tt>llvm/tools/Makefile</tt>.  The Release
 331 build requires considerably less space.</p>
 332
 333 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
 334 guaranteed to do so.  If compilation is successful, the LLVM utilities should be
 335 able to assemble, disassemble, analyze, and optimize LLVM bitcode.  Code
 336 generation should work as well, although the generated native code may not work
 337 on your platform.</p>
 338
 339 <p>The GCC front end is not very portable at the moment.  If you want to get it
 340 to work on another platform, you can download a copy of the source and <a
 341 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
 342
 343 </div>
 344
 345 <!-- ======================================================================= -->
 346 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
 347 <div class="doc_text">
 348   <p>Compiling LLVM requires that you have several software packages
 349   installed. The table below lists those required packages. The Package column
 350   is the usual name for the software package that LLVM depends on. The Version
 351   column provides "known to work" versions of the package. The Notes column
 352   describes how LLVM uses the package and provides other details.</p>
 353   <table summary="Packages required to compile LLVM">
 354     <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
 355
 356     <tr>
 357       <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
 358       <td>3.79, 3.79.1</td>
 359       <td>Makefile/build processor</td>
 360     </tr>
 361
 362     <tr>
 363       <td><a href="http://gcc.gnu.org">GCC</a></td>
 364       <td>3.4.2</td>
 365       <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
 366     </tr>
 367
 368     <tr>
 369       <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
 370       <td>4.5</td>
 371       <td>For building the CFE</td>
 372     </tr>
 373
 374     <tr>
 375       <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
 376       <td>2.5.4</td>
 377       <td>LEX compiler</td>
 378     </tr>
 379
 380     <tr>
 381       <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
 382       <td>1.28, 1.35, 1.75, 1.875d, 2.0, or 2.1<br>(not 1.85 or 1.875)</td>
 383       <td>YACC compiler</td>
 384     </tr>
 385
 386     <tr>
 387       <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
 388       <td>&ge;1.3</td>
 389       <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
 390     </tr>
 391
 392     <tr>
 393       <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
 394       <td>1.4.2</td>
 395       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 396     </tr>
 397
 398     <tr>
 399       <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
 400       <td>8.3, 8.4</td>
 401       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 402     </tr>
 403
 404     <tr>
 405       <td><a href="http://expect.nist.gov/">expect</a></td>
 406       <td>5.38.0</td>
 407       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 408     </tr>
 409
 410     <tr>
 411       <td><a href="http://www.perl.com/download.csp">perl</a></td>
 412       <td>&ge;5.6.0</td>
 413       <td>Nightly tester, utilities</td>
 414     </tr>
 415
 416     <tr>
 417       <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
 418       <td>1.4</td>
 419       <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
 420     </tr>
 421
 422     <tr>
 423       <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
 424       <td>2.59</td>
 425       <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
 426     </tr>
 427
 428     <tr>
 429       <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
 430       <td>1.9.2</td>
 431       <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
 432     </tr>
 433
 434     <tr>
 435       <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
 436       <td>1.5.10</td>
 437       <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
 438     </tr>
 439
 440   </table>
 441
 442   <p><b>Notes:</b></p>
 443   <div class="doc_notes">
 444   <ol>
 445     <li><a name="sf1">Only the C and C++ languages are needed so there's no
 446       need to build the other languages for LLVM's purposes.</a> See
 447       <a href="#brokengcc">below</a> for specific version info.</li>
 448     <li><a name="sf2">You only need Subversion if you intend to build from the
 449       latest LLVM sources. If you're working from a release distribution, you
 450       don't need Subversion.</a></li>
 451     <li><a name="sf3">Only needed if you want to run the automated test
 452       suite in the <tt>llvm/test</tt> directory.</a></li>
 453     <li><a name="sf4">If you want to make changes to the configure scripts,
 454       you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
 455       or higher). You will also need automake (1.9.2). We only use aclocal
 456       from that package.</a></li>
 457   </ol>
 458   </div>
 459
 460   <p>Additionally, your compilation host is expected to have the usual
 461   plethora of Unix utilities. Specifically:</p>
 462   <ul>
 463     <li><b>ar</b> - archive library builder</li>
 464     <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
 465     <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
 466     <li><b>chmod</b> - change permissions on a file</li>
 467     <li><b>cat</b> - output concatenation utility</li>
 468     <li><b>cp</b> - copy files</li>
 469     <li><b>date</b> - print the current date/time </li>
 470     <li><b>echo</b> - print to standard output</li>
 471     <li><b>egrep</b> - extended regular expression search utility</li>
 472     <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
 473     <li><b>find</b> - find files/dirs in a file system</li>
 474     <li><b>grep</b> - regular expression search utility</li>
 475     <li><b>gzip*</b> - gzip command for distribution generation</li>
 476     <li><b>gunzip*</b> - gunzip command for distribution checking</li>
 477     <li><b>install</b> - install directories/files </li>
 478     <li><b>mkdir</b> - create a directory</li>
 479     <li><b>mv</b> - move (rename) files</li>
 480     <li><b>ranlib</b> - symbol table builder for archive libraries</li>
 481     <li><b>rm</b> - remove (delete) files and directories</li>
 482     <li><b>sed</b> - stream editor for transforming output</li>
 483     <li><b>sh</b> - Bourne shell for make build scripts</li>
 484     <li><b>tar</b> - tape archive for distribution generation</li>
 485     <li><b>test</b> - test things in file system</li>
 486     <li><b>unzip*</b> - unzip command for distribution checking</li>
 487     <li><b>zip*</b> - zip command for distribution generation</li>
 488   </ul>
 489 </div>
 490
 491 <!-- ======================================================================= -->
 492 <div class="doc_subsection">
 493   <a name="brokengcc">Broken versions of GCC and other tools</a>
 494 </div>
 495
 496 <div class="doc_text">
 497
 498 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
 499 bugs in the compiler.  In particular, several versions of GCC crash when trying
 500 to compile LLVM.  We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
 501 successfully with them (however, see important notes below).  Other versions
 502 of GCC will probably work as well.  GCC versions listed
 503 here are known to not work.  If you are using one of these versions, please try
 504 to upgrade your GCC to something more recent.  If you run into a problem with a
 505 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
 506 us know</a>.  Please use the "<tt>gcc -v</tt>" command to find out which version
 507 of GCC you are using.
 508 </p>
 509
 510 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
 511 problems in the STL that effectively prevent it from compiling LLVM.
 512 </p>
 513
 514 <p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
 515
 516 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
 517 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
 518 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
 519
 520 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
 521    Cygwin does not work.  Please <a href="CFEBuildInstrs.html#cygwin">upgrade
 522    to a newer version</a> if possible.</p>
 523 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
 524    possibly others) does not compile LLVM correctly (it appears that exception
 525    handling is broken in some cases).  Please download the FSF 3.3.3 or upgrade
 526    to a newer version of GCC.</p>
 527 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 528    code generator, causing an infinite loop in the llvm-gcc build when built
 529    with optimizations enabled (i.e. a release build).</p>
 530 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 531    code generator at -O3, as with 3.4.0.  However gcc 3.4.2 (unlike 3.4.0)
 532    correctly compiles LLVM at -O2.  A work around is to build release LLVM
 533    builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
 534 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
 535    miscompiles portions of LLVM</a>.</p>
 536 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
 537    miscompile LLVM.</p>
 538 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
 539    default with ENABLE_OPTIMIZED=1.  To work around this, build with
 540    "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
 541 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
 542       compiling some files.  At the time of this writing, GCC mainline (4.2)
 543       did not share the problem.</p>
 544 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
 545    miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
 546    code.  LLVM will appear to mostly work but will be buggy, e.g. failing
 547    portions of its testsuite.</p>
 548 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
 549 platforms compiling md5.c gets a mangled constant.</p>
 550 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
 551 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
 552 defined in a discarded section. You can safely ignore these messages as they are
 553 erroneous and the linkage is correct.  These messages disappear using ld
 554 2.17.</p>
 555
 556 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
 557 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
 558 causes huge link times (minutes instead of seconds) when building LLVM.  We
 559 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
 560
 561 </div>
 562
 563
 564
 565 <!-- *********************************************************************** -->
 566 <div class="doc_section">
 567   <a name="starting"><b>Getting Started with LLVM</b></a>
 568 </div>
 569 <!-- *********************************************************************** -->
 570
 571 <div class="doc_text">
 572
 573 <p>The remainder of this guide is meant to get you up and running with
 574 LLVM and to give you some basic information about the LLVM environment.</p>
 575
 576 <p>The later sections of this guide describe the <a
 577 href="#layout">general layout</a> of the the LLVM source tree, a <a
 578 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 579 href="#links">links</a> to find more information about LLVM or to get
 580 help via e-mail.</p>
 581 </div>
 582
 583 <!-- ======================================================================= -->
 584 <div class="doc_subsection">
 585   <a name="terminology">Terminology and Notation</a>
 586 </div>
 587
 588 <div class="doc_text">
 589
 590 <p>Throughout this manual, the following names are used to denote paths
 591 specific to the local system and working environment.  <i>These are not
 592 environment variables you need to set but just strings used in the rest
 593 of this document below</i>.  In any of the examples below, simply replace
 594 each of these names with the appropriate pathname on your local system.
 595 All these paths are absolute:</p>
 596
 597 <dl>
 598     <dt>SRC_ROOT
 599     <dd>
 600     This is the top level directory of the LLVM source tree.
 601     <br><br>
 602
 603     <dt>OBJ_ROOT
 604     <dd>
 605     This is the top level directory of the LLVM object tree (i.e. the
 606     tree where object files and compiled programs will be placed.  It
 607     can be the same as SRC_ROOT).
 608     <br><br>
 609
 610     <dt>LLVMGCCDIR
 611     <dd>
 612     This is where the LLVM GCC Front End is installed.
 613     <p>
 614     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 615     <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
 616 </dl>
 617
 618 </div>
 619
 620 <!-- ======================================================================= -->
 621 <div class="doc_subsection">
 622   <a name="environment">Setting Up Your Environment</a>
 623 </div>
 624
 625 <div class="doc_text">
 626
 627 <p>
 628 In order to compile and use LLVM, you may need to set some environment
 629 variables.
 630
 631 <dl>
 632   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
 633   <dd>[Optional] This environment variable helps LLVM linking tools find the
 634   locations of your bitcode libraries. It is provided only as a
 635   convenience since you can specify the paths using the -L options of the
 636   tools and the C/C++ front-end will automatically use the bitcode files
 637   installed in its
 638   <tt>lib</tt> directory.</dd>
 639 </dl>
 640
 641 </div>
 642
 643 <!-- ======================================================================= -->
 644 <div class="doc_subsection">
 645   <a name="unpack">Unpacking the LLVM Archives</a>
 646 </div>
 647
 648 <div class="doc_text">
 649
 650 <p>
 651 If you have the LLVM distribution, you will need to unpack it before you
 652 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 653 suite and the LLVM GCC front end compiled for your platform.  There is an
 654 additional test suite that is optional.  Each file is a TAR archive that is
 655 compressed with the gzip program.
 656 </p>
 657
 658 <p>The files are as follows, with <em>x.y</em> marking the version number:
 659 <dl>
 660   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 661   <dd>Source release for the LLVM libraries and tools.<br/></dd>
 662
 663   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 664   <dd>Source release for the LLVM test suite.</dd>
 665
 666   <dt><tt>llvm-gcc4-x.y.source.tar.gz</tt></dt>
 667   <dd>Source release of the llvm-gcc4 front end.  See README.LLVM in the root
 668       directory for build instructions.<br/></dd>
 669
 670   <dt><tt>llvm-gcc4-x.y-platform.tar.gz</tt></dt>
 671   <dd>Binary release of the llvm-gcc4 front end for a specific platform.<br/></dd>
 672
 673 </dl>
 674
 675 <p>It is also possible to download the sources of the llvm-gcc4 front end from a
 676 read-only subversion mirror at
 677 svn://anonsvn.opensource.apple.com/svn/llvm/trunk. </p>
 678
 679 </div>
 680
 681 <!-- ======================================================================= -->
 682 <div class="doc_subsection">
 683   <a name="checkout">Checkout LLVM from Subversion</a>
 684 </div>
 685
 686 <div class="doc_text">
 687
 688 <p>If you have access to our Subversion repository, you can get a fresh copy of
 689 the entire source code.  All you need to do is check it out from Subvresion as
 690 follows:</p>
 691
 692 <ul>
 693   <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
 694   <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
 695   <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
 696     llvm</tt></li>
 697 </ul>
 698
 699
 700 <p>This will create an '<tt>llvm</tt>' directory in the current
 701 directory and fully populate it with the LLVM source code, Makefiles,
 702 test directories, and local copies of documentation files.</p>
 703
 704 <p>If you want to get a specific release (as opposed to the most recent
 705 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
 706 '<tt>trunk</tt>'). The following releases are located in the following
 707   subdirectories of the '<tt>tags</tt>' directory:</p>
 708
 709 <ul>
 710 <li>Release 2.0: <b>RELEASE_20</b></li>
 711 <li>Release 1.9: <b>RELEASE_19</b></li>
 712 <li>Release 1.8: <b>RELEASE_18</b></li>
 713 <li>Release 1.7: <b>RELEASE_17</b></li>
 714 <li>Release 1.6: <b>RELEASE_16</b></li>
 715 <li>Release 1.5: <b>RELEASE_15</b></li>
 716 <li>Release 1.4: <b>RELEASE_14</b></li>
 717 <li>Release 1.3: <b>RELEASE_13</b></li>
 718 <li>Release 1.2: <b>RELEASE_12</b></li>
 719 <li>Release 1.1: <b>RELEASE_11</b></li>
 720 <li>Release 1.0: <b>RELEASE_1</b></li>
 721 </ul>
 722
 723 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 724 you get it from the Subversion repository:</p>
 725
 726 <div class="doc_code">
 727 <pre>
 728 % cd llvm/projects
 729 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
 730 </pre>
 731 </div>
 732
 733 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 734 configured by the LLVM configure script as well as automatically updated when
 735 you run <tt>svn update</tt>.</p>
 736
 737 <p>If you would like to get the GCC front end source code, you can also get it
 738 and build it yourself.  Please follow <a href="CFEBuildInstrs.html">these
 739 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
 740
 741 </div>
 742
 743 <!-- ======================================================================= -->
 744 <div class="doc_subsection">
 745   <a name="installcf">Install the GCC Front End</a>
 746 </div>
 747
 748 <div class="doc_text">
 749
 750 <p>Before configuring and compiling the LLVM suite, you can optionally extract the
 751 LLVM GCC front end from the binary distribution.  It is used for running the
 752 llvm-test testsuite and for compiling C/C++ programs.  Note that you can optionally
 753 <a href="CFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
 754 main LLVM repository.</p>
 755
 756 <p>To install the GCC front end, do the following:</p>
 757
 758 <ol>
 759   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 760   <li><tt>gunzip --stdout llvmgcc-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
 761       -</tt></li>
 762 </ol>
 763
 764 <p>Once the binary is uncompressed, you should add a symlink for llvm-gcc and
 765 llvm-g++ to some directory in your path.  When you configure LLVM, it will
 766 automatically detect llvm-gcc's presence (if it is in your path) enabling its
 767 use in llvm-test.  Note that you can always build or install llvm-gcc at any
 768 pointer after building the main LLVM repository: just reconfigure llvm and
 769 llvm-test will pick it up.
 770 </p>
 771
 772 <p>The binary versions of the GCC front end may not suit all of your needs.  For
 773 example, the binary distribution may include an old version of a system header
 774 file, not "fix" a header file that needs to be fixed for GCC, or it may be
 775 linked with libraries not available on your system.</p>
 776
 777 <p>In cases like these, you may want to try <a
 778 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
 779 much easier now than it was in the past.</p>
 780
 781 </div>
 782
 783 <!-- ======================================================================= -->
 784 <div class="doc_subsection">
 785   <a name="config">Local LLVM Configuration</a>
 786 </div>
 787
 788 <div class="doc_text">
 789
 790   <p>Once checked out from the Subversion repository, the LLVM suite source
 791   code must be
 792 configured via the <tt>configure</tt> script.  This script sets variables in the
 793 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 794 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 795 the Makefiles needed to begin building LLVM.</p>
 796
 797 <p>The following environment variables are used by the <tt>configure</tt>
 798 script to configure the build system:</p>
 799
 800 <table summary="LLVM configure script environment variables">
 801   <tr><th>Variable</th><th>Purpose</th></tr>
 802   <tr>
 803     <td>CC</td>
 804     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 805         <tt>configure</tt> will look for the first GCC C compiler in
 806         <tt>PATH</tt>.  Use this variable to override
 807         <tt>configure</tt>'s default behavior.</td>
 808   </tr>
 809   <tr>
 810     <td>CXX</td>
 811     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 812        <tt>configure</tt> will look for the first GCC C++ compiler in
 813        <tt>PATH</tt>.  Use this variable to override
 814        <tt>configure</tt>'s default behavior.</td>
 815   </tr>
 816 </table>
 817
 818 <p>The following options can be used to set or enable LLVM specific options:</p>
 819
 820 <dl>
 821   <dt><i>--with-llvmgccdir</i></dt>
 822   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 823   The value of this option should specify the full pathname of the C/C++ Front
 824   End to be used. If this option is not provided, the PATH will be searched for
 825   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 826   be inferred from the path found. If the option is not given, and no llvm-gcc
 827   can be found in the path then a warning will be produced by
 828   <tt>configure</tt> indicating this situation. LLVM may still be built with
 829   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 830   will fail as these libraries require llvm-gcc and llvm-g++. See
 831   <a href="#installcf">Install the GCC Front End</a> for details on installing
 832   the C/C++ Front End. See
 833   <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 834   for details on building the C/C++ Front End.</dd>
 835   <dt><i>--with-tclinclude</i></dt>
 836   <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
 837   found. Use this if you have multiple tcl installations on your machine and you
 838   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 839   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 840   option, the LLVM configure script will search for the tcl 8.4 and 8.3
 841   releases.
 842   <br><br>
 843   </dd>
 844   <dt><i>--enable-optimized</i></dt>
 845   <dd>
 846     Enables optimized compilation by default (debugging symbols are removed
 847     and GCC optimization flags are enabled).  The default is to use an
 848     unoptimized build (also known as a debug build).
 849     <br><br>
 850   </dd>
 851   <dt><i>--enable-debug-runtime</i></dt>
 852   <dd>
 853     Enables debug symbols in the runtime libraries. The default is to strip
 854     debug symbols from the runtime libraries.
 855   </dd>
 856   <dt><i>--enable-jit</i></dt>
 857   <dd>
 858     Compile the Just In Time (JIT) compiler functionality.  This is not
 859     available
 860     on all platforms.  The default is dependent on platform, so it is best
 861     to explicitly enable it if you want it.
 862     <br><br>
 863   </dd>
 864   <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
 865   <dd>Controls which targets will be built and linked into llc. The default
 866   value for <tt>target_options</tt> is "all" which builds and links all
 867   available targets.  The value "host-only" can be specified to build only a
 868   native compiler (no cross-compiler targets available). The "native" target is
 869   selected as the target of the build host. You can also specify a comma
 870   separated list of target names that you want available in llc. The target
 871   names use all lower case. The current set of targets is: <br/>
 872   <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
 873   <br><br></dd>
 874   <dt><i>--enable-doxygen</i></dt>
 875   <dd>Look for the doxygen program and enable construction of doxygen based
 876   documentation from the source code. This is disabled by default because
 877   generating the documentation can take a long time and producess 100s of
 878   megabytes of output.</dd>
 879   <dt><i>--with-udis86</i></dt>
 880   <dd>LLVM can use external disassembler library for various purposes (now it's
 881   used only for examining code produced by JIT). This option will enable usage
 882   of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
 883   bits) disassembler library.</dd>
 884 </dl>
 885
 886 <p>To configure LLVM, follow these steps:</p>
 887
 888 <ol>
 889     <li><p>Change directory into the object root directory:</p>
 890
 891     <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
 892
 893     <li><p>Run the <tt>configure</tt> script located in the LLVM source
 894     tree:</p>
 895
 896     <div class="doc_code">
 897     <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
 898     </div></li>
 899 </ol>
 900
 901 </div>
 902
 903 <!-- ======================================================================= -->
 904 <div class="doc_subsection">
 905   <a name="compile">Compiling the LLVM Suite Source Code</a>
 906 </div>
 907
 908 <div class="doc_text">
 909
 910 <p>Once you have configured LLVM, you can build it.  There are three types of
 911 builds:</p>
 912
 913 <dl>
 914     <dt>Debug Builds
 915     <dd>
 916     These builds are the default when one types <tt>gmake</tt> (unless the
 917     <tt>--enable-optimized</tt> option was used during configuration).  The
 918     build system will compile the tools and libraries with debugging
 919     information.
 920     <br><br>
 921
 922     <dt>Release (Optimized) Builds
 923     <dd>
 924     These builds are enabled with the <tt>--enable-optimized</tt> option to
 925     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 926     <tt>gmake</tt> command line.  For these builds, the build system will
 927     compile the tools and libraries with GCC optimizations enabled and strip
 928     debugging information from the libraries and executables it generates.
 929     <br><br>
 930
 931     <dt>Profile Builds
 932     <dd>
 933     These builds are for use with profiling.  They compile profiling
 934     information into the code for use with programs like <tt>gprof</tt>.
 935     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
 936     on the <tt>gmake</tt> command line.
 937 </dl>
 938
 939 <p>Once you have LLVM configured, you can build it by entering the
 940 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
 941
 942 <div class="doc_code"><pre>% gmake</pre></div>
 943
 944 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
 945 are using a version of GCC that is known not to compile LLVM.</p>
 946
 947 <p>
 948 If you have multiple processors in your machine, you may wish to use some of
 949 the parallel build options provided by GNU Make.  For example, you could use the
 950 command:</p>
 951
 952 <div class="doc_code"><pre>% gmake -j2</pre></div>
 953
 954 <p>There are several special targets which are useful when working with the LLVM
 955 source code:</p>
 956
 957 <dl>
 958   <dt><tt>gmake clean</tt>
 959   <dd>
 960   Removes all files generated by the build.  This includes object files,
 961   generated C/C++ files, libraries, and executables.
 962   <br><br>
 963
 964   <dt><tt>gmake dist-clean</tt>
 965   <dd>
 966   Removes everything that <tt>gmake clean</tt> does, but also removes files
 967   generated by <tt>configure</tt>.  It attempts to return the source tree to the
 968   original state in which it was shipped.
 969   <br><br>
 970
 971   <dt><tt>gmake install</tt>
 972   <dd>
 973   Installs LLVM header files, libraries, tools, and documentation in a
 974   hierarchy
 975   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
 976   defaults to <tt>/usr/local</tt>.
 977   <br><br>
 978
 979   <dt><tt>gmake -C runtime install-bytecode</tt>
 980   <dd>
 981   Assuming you built LLVM into $OBJDIR, when this command is run, it will
 982   install bitcode libraries into the GCC front end's bitcode library
 983   directory.  If you need to update your bitcode libraries,
 984   this is the target to use once you've built them.
 985   <br><br>
 986 </dl>
 987
 988 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
 989 details on these <tt>make</tt> targets and descriptions of other targets
 990 available.</p>
 991
 992 <p>It is also possible to override default values from <tt>configure</tt> by
 993 declaring variables on the command line.  The following are some examples:</p>
 994
 995 <dl>
 996   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
 997   <dd>
 998   Perform a Release (Optimized) build.
 999   <br><br>
1000
1001   <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1002   <dd>
1003   Perform a Release (Optimized) build without assertions enabled.
1004   <br><br>
1005
1006   <dt><tt>gmake ENABLE_PROFILING=1</tt>
1007   <dd>
1008   Perform a Profiling build.
1009   <br><br>
1010
1011   <dt><tt>gmake VERBOSE=1</tt>
1012   <dd>
1013   Print what <tt>gmake</tt> is doing on standard output.
1014   <br><br>
1015
1016   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1017   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1018   the standard output. This also implies <tt>VERBOSE=1</tt>.
1019   <br><br></dd>
1020 </dl>
1021
1022 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1023 it and any subdirectories that it contains.  Entering any directory inside the
1024 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1025 that directory that is out of date.</p>
1026
1027 </div>
1028
1029 <!-- ======================================================================= -->
1030 <div class="doc_subsection">
1031   <a name="cross-compile">Cross-Compiling LLVM</a>
1032 </div>
1033
1034 <div class="doc_text">
1035   <p>It is possible to cross-compile LLVM. That is, you can create LLVM
1036   executables and libraries for a platform different than the one one which you
1037   are compiling.  To do this, a few additional steps are
1038   required. <sup><a href="#ccn_1">1</a></sup> To cross-compile LLVM, use
1039   these instructions:</p>
1040   <ol>
1041     <li>Configure and build LLVM as a native compiler. You will need
1042     just <tt>TableGen</tt> from that build.
1043       <ul>
1044         <li>If you have <tt>$LLVM_OBJ_ROOT=$LLVM_SRC_ROOT</tt> just execute
1045           <tt>make -C utils/TableGen</tt> after configuring.</li>
1046         <li>Otherwise you will need to monitor building process and terminate
1047           it just after <tt>TableGen</tt> was built.</li>
1048       </ul>
1049     </li>
1050     <li>Copy the TableGen binary to somewhere safe (out of your build tree).
1051     </li>
1052     <li>Configure LLVM to build with a cross-compiler. To do this, supply the
1053     configure script with <tt>--build</tt> and <tt>--host</tt> options that
1054     are different. The values of these options must be legal target triples
1055     that your GCC compiler supports.</li>
1056     <li>Put the saved <tt>TableGen</tt> executable into the
1057     into <tt>$LLVM_OBJ_ROOT/{BUILD_TYPE}/bin</tt> directory (e.g. into
1058     <tt>.../Release/bin</tt> for a Release build).</li>
1059     <li>Build LLVM  as usual.</li>
1060   </ol>
1061   <p>The result of such a build will produce executables that are not executable
1062   on your build host (--build option) but can be executed on your compile host
1063   (--host option).</p>
1064   <p><b>Notes:</b></p>
1065   <div class="doc_notes">
1066     <ol>
1067       <li><a name="ccn_1">Cross-compiling</a> was tested only with Linux as
1068       build platform and Windows as host using mingw32 cross-compiler. Other
1069       combinations have not been tested.</li>
1070     </ol>
1071   </div>
1072 </div>
1073
1074 <!-- ======================================================================= -->
1075 <div class="doc_subsection">
1076   <a name="objfiles">The Location of LLVM Object Files</a>
1077 </div>
1078
1079 <div class="doc_text">
1080
1081 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1082 several LLVM builds.  Hence, it is possible to build LLVM for several different
1083 platforms or configurations using the same source tree.</p>
1084
1085 <p>This is accomplished in the typical autoconf manner:</p>
1086
1087 <ul>
1088   <li><p>Change directory to where the LLVM object files should live:</p>
1089
1090       <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1091
1092   <li><p>Run the <tt>configure</tt> script found in the LLVM source
1093       directory:</p>
1094
1095       <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1096 </ul>
1097
1098 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1099 named after the build type:</p>
1100
1101 <dl>
1102   <dt>Debug Builds
1103   <dd>
1104   <dl>
1105     <dt>Tools
1106     <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
1107     <dt>Libraries
1108     <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
1109   </dl>
1110   <br><br>
1111
1112   <dt>Release Builds
1113   <dd>
1114   <dl>
1115     <dt>Tools
1116     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1117     <dt>Libraries
1118     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1119   </dl>
1120   <br><br>
1121
1122   <dt>Profile Builds
1123   <dd>
1124   <dl>
1125     <dt>Tools
1126     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1127     <dt>Libraries
1128     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1129   </dl>
1130 </dl>
1131
1132 </div>
1133
1134 <!-- ======================================================================= -->
1135 <div class="doc_subsection">
1136   <a name="optionalconfig">Optional Configuration Items</a>
1137 </div>
1138
1139 <div class="doc_text">
1140
1141 <p>
1142 If you're running on a Linux system that supports the "<a
1143 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1144 module, and you have root access on the system, you can set your system up to
1145 execute LLVM bitcode files directly. To do this, use commands like this (the
1146 first command may not be required if you are already using the module):</p>
1147
1148 <div class="doc_code">
1149 <pre>
1150 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1151 $ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1152 $ chmod u+x hello.bc   (if needed)
1153 $ ./hello.bc
1154 </pre>
1155 </div>
1156
1157 <p>
1158 This allows you to execute LLVM bitcode files directly.  Thanks to Jack
1159 Cummings for pointing this out!
1160 </p>
1161
1162 </div>
1163
1164
1165 <!-- *********************************************************************** -->
1166 <div class="doc_section">
1167   <a name="layout"><b>Program Layout</b></a>
1168 </div>
1169 <!-- *********************************************************************** -->
1170
1171 <div class="doc_text">
1172
1173 <p>One useful source of information about the LLVM source base is the LLVM <a
1174 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1175 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1176 The following is a brief introduction to code layout:</p>
1177
1178 </div>
1179
1180 <!-- ======================================================================= -->
1181 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1182 <div class="doc_text">
1183   <p>This directory contains some simple examples of how to use the LLVM IR and
1184   JIT.</p>
1185 </div>
1186
1187 <!-- ======================================================================= -->
1188 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1189 <div class="doc_text">
1190
1191 <p>This directory contains public header files exported from the LLVM
1192 library. The three main subdirectories of this directory are:</p>
1193
1194 <dl>
1195   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1196   <dd>This directory contains all of the LLVM specific header files.  This
1197   directory also has subdirectories for different portions of LLVM:
1198   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1199   etc...</dd>
1200
1201   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1202   <dd>This directory contains generic support libraries that are provided with
1203   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1204   and a Command Line option processing library store their header files here.
1205   </dd>
1206
1207   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1208   <dd>This directory contains header files configured by the <tt>configure</tt>
1209   script.  They wrap "standard" UNIX and C header files.  Source code can
1210   include these header files which automatically take care of the conditional
1211   #includes that the <tt>configure</tt> script generates.</dd>
1212 </dl>
1213 </div>
1214
1215 <!-- ======================================================================= -->
1216 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1217 <div class="doc_text">
1218
1219 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1220 almost all code exists in libraries, making it very easy to share code among the
1221 different <a href="#tools">tools</a>.</p>
1222
1223 <dl>
1224   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1225   <dd> This directory holds the core LLVM source files that implement core
1226   classes like Instruction and BasicBlock.</dd>
1227
1228   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1229   <dd>This directory holds the source code for the LLVM assembly language parser
1230   library.</dd>
1231
1232   <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1233   <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1234
1235   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1236   different program analyses, such as Dominator Information, Call Graphs,
1237   Induction Variables, Interval Identification, Natural Loop Identification,
1238   etc.</dd>
1239
1240   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1241   <dd> This directory contains the source code for the LLVM to LLVM program
1242   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1243   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1244   Elimination, and many others.</dd>
1245
1246   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1247   <dd> This directory contains files that describe various target architectures
1248   for code generation.  For example, the <tt>llvm/lib/Target/X86</tt>
1249   directory holds the X86 machine description while
1250   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1251
1252   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1253   <dd> This directory contains the major parts of the code generator: Instruction
1254   Selector, Instruction Scheduling, and Register Allocation.</dd>
1255
1256   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1257   <dd> This directory contains the source level debugger library that makes
1258   it possible to instrument LLVM programs so that a debugger could identify
1259   source code locations at which the program is executing.</dd>
1260
1261   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1262   <dd> This directory contains libraries for executing LLVM bitcode directly
1263   at runtime in both interpreted and JIT compiled fashions.</dd>
1264
1265   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1266   <dd> This directory contains the source code that corresponds to the header
1267   files located in <tt>llvm/include/Support/</tt>.</dd>
1268
1269   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1270   <dd>This directory contains the operating system abstraction layer that
1271   shields LLVM from platform-specific coding.</dd>
1272 </dl>
1273
1274 </div>
1275
1276 <!-- ======================================================================= -->
1277 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1278 <div class="doc_text">
1279   <p>This directory contains projects that are not strictly part of LLVM but are
1280   shipped with LLVM. This is also the directory where you should create your own
1281   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1282   to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1283   functional example of a compiler front end.</p>
1284 </div>
1285
1286 <!-- ======================================================================= -->
1287 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1288 <div class="doc_text">
1289
1290 <p>This directory contains libraries which are compiled into LLVM bitcode and
1291 used when linking programs with the GCC front end.  Most of these libraries are
1292 skeleton versions of real libraries; for example, libc is a stripped down
1293 version of glibc.</p>
1294
1295 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1296 end to compile.</p>
1297
1298 </div>
1299
1300 <!-- ======================================================================= -->
1301 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1302 <div class="doc_text">
1303   <p>This directory contains feature and regression tests and other basic sanity
1304   checks on the LLVM infrastructure. These are intended to run quickly and cover
1305   a lot of territory without being exhaustive.</p>
1306 </div>
1307
1308 <!-- ======================================================================= -->
1309 <div class="doc_subsection"><a name="llvmtest"><tt>test-suite</tt></a></div>
1310 <div class="doc_text">
1311   <p>This is not a directory in the normal llvm module; it is a separate
1312   Subversion
1313   module that must be checked out (usually to <tt>projects/test-suite</tt>).
1314   This
1315   module contains a comprehensive correctness, performance, and benchmarking
1316   test
1317   suite for LLVM. It is a separate Subversion module because not every LLVM
1318   user is
1319   interested in downloading or building such a comprehensive test suite. For
1320   further details on this test suite, please see the
1321   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1322 </div>
1323
1324 <!-- ======================================================================= -->
1325 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1326 <div class="doc_text">
1327
1328 <p>The <b>tools</b> directory contains the executables built out of the
1329 libraries above, which form the main part of the user interface.  You can
1330 always get help for a tool by typing <tt>tool_name --help</tt>.  The
1331 following is a brief introduction to the most important tools.  More detailed
1332 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1333
1334 <dl>
1335
1336   <dt><tt><b>bugpoint</b></tt></dt>
1337   <dd><tt>bugpoint</tt> is used to debug
1338   optimization passes or code generation backends by narrowing down the
1339   given test case to the minimum number of passes and/or instructions that
1340   still cause a problem, whether it is a crash or miscompilation. See <a
1341   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1342   on using <tt>bugpoint</tt>.</dd>
1343
1344   <dt><tt><b>llvmc</b></tt></dt>
1345   <dd>The LLVM Compiler Driver. This program can
1346   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1347   pre-processing, translation, optimization, assembly, and linking of programs
1348   all from one command line. <tt>llvmc</tt> also takes care of processing the
1349   dependent libraries found in bitcode. This reduces the need to get the
1350   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1351   note that this tool, while functional, is still experimental and not feature
1352   complete.</dd>
1353
1354   <dt><tt><b>llvm-ar</b></tt></dt>
1355   <dd>The archiver produces an archive containing
1356   the given LLVM bitcode files, optionally with an index for faster
1357   lookup.</dd>
1358
1359   <dt><tt><b>llvm-as</b></tt></dt>
1360   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1361   bitcode.</dd>
1362
1363   <dt><tt><b>llvm-dis</b></tt></dt>
1364   <dd>The disassembler transforms the LLVM bitcode to human readable
1365   LLVM assembly.</dd>
1366
1367   <dt><tt><b>llvm-ld</b></tt></dt>
1368   <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1369   This is the linker invoked by <tt>llvmc</tt>. It performsn standard link time
1370   optimizations and allows optimization modules to be loaded and run so that
1371   language specific optimizations can be applied at link time.</dd>
1372
1373   <dt><tt><b>llvm-link</b></tt></dt>
1374   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1375   a single program.</dd>
1376
1377   <dt><tt><b>lli</b></tt></dt>
1378   <dd><tt>lli</tt> is the LLVM interpreter, which
1379   can directly execute LLVM bitcode (although very slowly...). In addition
1380   to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1381   specifying <tt>-trace</tt> on the command line). Finally, for
1382   architectures that support it (currently x86, Sparc, and PowerPC), by default,
1383   <tt>lli</tt> will function as a Just-In-Time compiler (if the
1384   functionality was compiled in), and will execute the code <i>much</i>
1385   faster than the interpreter.</dd>
1386
1387   <dt><tt><b>llc</b></tt></dt>
1388   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1389   translates LLVM bitcode to a native code assembly file or to C code (with
1390   the -march=c option).</dd>
1391
1392   <dt><tt><b>llvm-gcc</b></tt></dt>
1393   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1394   use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1395   bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1396   usual machine code output.  It works just like any other GCC compiler,
1397   taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1398   Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1399   separate Subversion module.</dd>
1400
1401   <dt><tt><b>opt</b></tt></dt>
1402   <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1403   transformations (which are specified on the command line), and then outputs
1404   the resultant bitcode.  The '<tt>opt --help</tt>' command is a good way to
1405   get a list of the program transformations available in LLVM.<br/>
1406   <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1407   LLVM bitcode file and print out the results.  It is primarily useful for
1408   debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1409 </dl>
1410 </div>
1411
1412 <!-- ======================================================================= -->
1413 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1414 <div class="doc_text">
1415
1416 <p>This directory contains utilities for working with LLVM source code, and some
1417 of the utilities are actually required as part of the build process because they
1418 are code generators for parts of LLVM infrastructure.</p>
1419
1420 <dl>
1421   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1422   that finds differences between code that LLC generates and code that LLI
1423   generates. This is a useful tool if you are debugging one of them,
1424   assuming that the other generates correct output. For the full user
1425   manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1426
1427   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1428   syntax-highlighting files which will work with Emacs and XEmacs editors,
1429   providing syntax highlighting support for LLVM assembly files and TableGen
1430   description files. For information on how to use the syntax files, consult
1431   the <tt>README</tt> file in that directory.<br><br>
1432
1433   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1434   and outputs all non-generated source files, which is useful if one wishes
1435   to do a lot of development across directories and does not want to
1436   individually find each file. One way to use it is to run, for example:
1437   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1438   tree.<br><br>
1439
1440   <dt><tt><b>llvmgrep</b></tt></dt>
1441   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1442   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1443   line. This is a very efficient way of searching the source base for a
1444   particular regular expression.</dd>
1445
1446   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1447   files in the current directory and then compiles and links the tool that
1448   is the first argument. For example, assuming you are in the directory
1449   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1450   simply running <tt>makellvm llc</tt> will make a build of the current
1451   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1452   causing a re-linking of LLC.<br><br>
1453
1454   <dt><tt><b>NewNightlyTest.pl</b></tt> and
1455   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1456   cron script to generate nightly status reports of the functionality of
1457   tools, and the results can be seen by following the appropriate link on
1458   the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1459
1460   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1461   the tool used to generate register descriptions, instruction set
1462   descriptions, and even assemblers from common TableGen description
1463   files.<br><br>
1464
1465   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1466   syntax-highlighting files which will work with the VIM editor, providing
1467   syntax highlighting support for LLVM assembly files and TableGen
1468   description files. For information on how to use the syntax files, consult
1469   the <tt>README</tt> file in that directory.<br><br>
1470
1471 </dl>
1472
1473 </div>
1474
1475 <!-- ======================================================================= -->
1476 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1477 <div class="doc_text">
1478   <p>This directory contains build scripts and project files for use with
1479   Visual C++. This allows developers on Windows to build LLVM without the need
1480   for Cygwin. The contents of this directory should be considered experimental
1481   at this time.
1482   </p>
1483 </div>
1484 <!-- *********************************************************************** -->
1485 <div class="doc_section">
1486   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1487 </div>
1488 <!-- *********************************************************************** -->
1489
1490 <div class="doc_text">
1491 <p>This section gives an example of using LLVM.  llvm-gcc3 is now obsolete,
1492 so we only include instructiosn for llvm-gcc4.
1493 </p>
1494
1495 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1496 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1497 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1498 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1499 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1500 output.</p>
1501 </div>
1502
1503 <!-- ======================================================================= -->
1504 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1505
1506 <div class="doc_text">
1507
1508 <ol>
1509   <li><p>First, create a simple C file, name it 'hello.c':</p>
1510
1511 <div class="doc_code">
1512 <pre>
1513 #include &lt;stdio.h&gt;
1514
1515 int main() {
1516   printf("hello world\n");
1517   return 0;
1518 }
1519 </pre></div></li>
1520
1521   <li><p>Next, compile the C file into a native executable:</p>
1522
1523       <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1524
1525       <p>Note that llvm-gcc works just like GCC by default.  The standard -S and
1526         -c arguments work as usual (producing a native .s or .o file,
1527         respectively).</p></li>
1528
1529   <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1530
1531       <div class="doc_code">
1532       <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1533
1534       <p>The -emit-llvm option can be used with the -S or -c options to emit an
1535          LLVM ".ll" or ".bc" file (respectively) for the code.  This allows you
1536          to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1537          the bitcode file.</p>
1538
1539       <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1540          </p></li>
1541
1542   <li><p>Run the program in both forms. To run the program, use:</p>
1543
1544       <div class="doc_code"><pre>% ./hello</pre></div>
1545
1546       <p>and</p>
1547
1548       <div class="doc_code"><pre>% lli hello.bc</pre></div>
1549
1550       <p>The second examples shows how to invoke the LLVM JIT, <a
1551        href="CommandGuide/html/lli.html">lli</a>.</p></li>
1552
1553   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1554       code:</p>
1555
1556 <div class="doc_code">
1557 <pre>llvm-dis &lt; hello.bc | less</pre>
1558 </div></li>
1559
1560   <li><p>Compile the program to native assembly using the LLC code
1561       generator:</p>
1562
1563       <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1564
1565   <li><p>Assemble the native assembly language file into a program:</p>
1566
1567 <div class="doc_code">
1568 <pre>
1569 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1570
1571 <b>Others:</b>  % gcc hello.s -o hello.native
1572 </pre>
1573 </div></li>
1574
1575   <li><p>Execute the native code program:</p>
1576
1577       <div class="doc_code"><pre>% ./hello.native</pre></div>
1578
1579       <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1580          the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1581         </li>
1582
1583 </ol>
1584
1585 </div>
1586
1587
1588 <!-- *********************************************************************** -->
1589 <div class="doc_section">
1590   <a name="problems">Common Problems</a>
1591 </div>
1592 <!-- *********************************************************************** -->
1593
1594 <div class="doc_text">
1595
1596 <p>If you are having problems building or using LLVM, or if you have any other
1597 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1598 Asked Questions</a> page.</p>
1599
1600 </div>
1601
1602 <!-- *********************************************************************** -->
1603 <div class="doc_section">
1604   <a name="links">Links</a>
1605 </div>
1606 <!-- *********************************************************************** -->
1607
1608 <div class="doc_text">
1609
1610 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1611 some simple things... there are many more interesting and complicated things
1612 that you can do that aren't documented here (but we'll gladly accept a patch
1613 if you want to write something up!).  For more information about LLVM, check
1614 out:</p>
1615
1616 <ul>
1617   <li><a href="http://llvm.org/">LLVM homepage</a></li>
1618   <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
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1624
1625 <!-- *********************************************************************** -->
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1633
1634   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
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