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  10
  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</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 CVS</a>
  31       <li><a href="#installcf">Install the GCC Front End</a>
  32       <li><a href="#config">Local LLVM Configuration</a>
  33       <li><a href="#compile">Compiling the LLVM Suite Source Code</a>
  34       <li><a href="#objfiles">The Location of LLVM Object Files</a>
  35       <li><a href="#optionalconfig">Optional Configuration Items</a>
  36     </ol></li>
  37
  38   <li><a href="#layout">Program layout</a>
  39     <ol>
  40       <li><a href="#cvsdir"><tt>CVS</tt> directories</a>
  41       <li><a href="#examples"><tt>llvm/examples</tt></a>
  42       <li><a href="#include"><tt>llvm/include</tt></a>
  43       <li><a href="#lib"><tt>llvm/lib</tt></a>
  44       <li><a href="#projects"><tt>llvm/projects</tt></a>
  45       <li><a href="#runtime"><tt>llvm/runtime</tt></a>
  46       <li><a href="#test"><tt>llvm/test</tt></a>
  47       <li><a href="#llvmtest"><tt>llvm-test</tt></a>
  48       <li><a href="#tools"><tt>llvm/tools</tt></a>
  49       <li><a href="#utils"><tt>llvm/utils</tt></a>
  50       <li><a href="#win32"><tt>llvm/win32</tt></a>
  51     </ol></li>
  52
  53   <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
  54   <li><a href="#problems">Common Problems</a>
  55   <li><a href="#links">Links</a>
  56 </ul>
  57
  58 <div class="doc_author">
  59   <p>Written by:
  60     <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
  61     <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
  62     <a href="http://misha.brukman.net">Misha Brukman</a>,
  63     <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
  64     <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
  65   </p>
  66 </div>
  67
  68
  69 <!-- *********************************************************************** -->
  70 <div class="doc_section">
  71   <a name="overview"><b>Overview</b></a>
  72 </div>
  73 <!-- *********************************************************************** -->
  74
  75 <div class="doc_text">
  76
  77 <p>Welcome to LLVM! In order to get started, you first need to know some
  78 basic information.</p>
  79
  80 <p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
  81 contains all of the tools, libraries, and header files needed to use the low
  82 level virtual machine.  It contains an assembler, disassembler, bytecode
  83 analyzer, and bytecode optimizer.  It also contains a test suite that can be
  84 used to test the LLVM tools and the GCC front end.</p>
  85
  86 <p>The second piece is the GCC front end.  This component provides a version of
  87 GCC that compiles C and C++ code into LLVM bytecode.  Currently, the GCC front
  88 end is a modified version of GCC 3.4 (we track the GCC 3.4 development).  Once
  89 compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
  90 from the LLVM suite.</p>
  91
  92 <p>
  93 There is a third, optional piece called llvm-test.  It is a suite of programs
  94 with a testing harness that can be used to further test LLVM's functionality
  95 and performance.
  96 </p>
  97
  98 </div>
  99
 100 <!-- *********************************************************************** -->
 101 <div class="doc_section">
 102   <a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
 103 </div>
 104 <!-- *********************************************************************** -->
 105
 106 <div class="doc_text">
 107
 108 <p>Here's the short story for getting up and running quickly with LLVM:</p>
 109
 110 <ol>
 111   <li>Read the documentation.</li>
 112   <li>Read the documentation.</li>
 113   <li>Remember that you were warned twice about reading the documentation.</li>
 114   <li>Install the GCC front end if you intend to compile C or C++:
 115     <ol>
 116       <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
 117       <li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
 118       </li>
 119       <li><tt>cd cfrontend/<i>platform</i><br>
 120         ./fixheaders</tt></li>
 121       <li>Add the cfrontend's "bin" directory to your PATH variable</li>
 122     </ol></li>
 123
 124   <li>Get the LLVM Source Code
 125   <ul>
 126     <li>With the distributed files (or use <a href="#checkout">CVS</a>):
 127     <ol>
 128       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 129       <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
 130     </ol></li>
 131
 132   </ul></li>
 133
 134   <li><b>[Optional]</b> Get the Test Suite Source Code
 135   <ul>
 136     <li>With the distributed files (or use <a href="#checkout">CVS</a>):
 137     <ol>
 138       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 139       <li><tt>cd llvm/projects</tt>
 140       <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
 141     </ol></li>
 142
 143   </ul></li>
 144
 145
 146   <li>Configure the LLVM Build Environment
 147   <ol>
 148     <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
 149     <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
 150     Some common options:
 151
 152       <ul>
 153         <li><tt>--prefix=<i>directory</i></tt>
 154         <p>Specify for <i>directory</i> the full pathname of where you
 155         want the LLVM tools and libraries to be installed (default
 156         <tt>/usr/local</tt>).</p></li>
 157         <li><tt>--with-llvmgccdir=<i>directory</i></tt>
 158         <p>Optionally, specify for <i>directory</i> the full pathname of the
 159         C/C++ FrontEnd installation to use with this LLVM configuration. If
 160         not specified, the PATH will be searched.</p></li>
 161         <li><tt>--enable-spec2000=<i>directory</i></tt>
 162             <p>Enable the SPEC2000 benchmarks for testing.  The SPEC2000
 163             benchmarks should be available in
 164             <tt><i>directory</i></tt>.</p></li>
 165       </ul>
 166   </ol></li>
 167
 168   <li>Build the LLVM Suite:
 169   <ol>
 170       <li><tt>gmake -k |&amp; tee gnumake.out
 171       &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
 172       <li>If you get an "internal compiler error (ICE)" see <a href="#brokengcc">below</a>.</li>
 173   </ol>
 174
 175 </ol>
 176
 177 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
 178 detailed information on configuring and compiling LLVM.  See <a
 179 href="#environment">Setting Up Your Environment</a> for tips that simplify
 180 working with the GCC front end and LLVM tools.  Go to <a href="#layout">Program
 181 Layout</a> to learn about the layout of the source code tree.</p>
 182
 183 </div>
 184
 185 <!-- *********************************************************************** -->
 186 <div class="doc_section">
 187   <a name="requirements"><b>Requirements</b></a>
 188 </div>
 189 <!-- *********************************************************************** -->
 190
 191 <div class="doc_text">
 192
 193 <p>Before you begin to use the LLVM system, review the requirements given below.
 194 This may save you some trouble by knowing ahead of time what hardware and
 195 software you will need.</p>
 196
 197 </div>
 198
 199 <!-- ======================================================================= -->
 200 <div class="doc_subsection">
 201   <a name="hardware"><b>Hardware</b></a>
 202 </div>
 203
 204 <div class="doc_text">
 205
 206 <p>LLVM is known to work on the following platforms:</p>
 207
 208 <table cellpadding="3">
 209 <tr>
 210   <th>OS</th>
 211   <th>Arch</th>
 212   <th>Compilers</th>
 213 </tr>
 214 <tr>
 215   <td>Linux</td>
 216   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 217   <td>GCC</td>
 218 </tr>
 219 <tr>
 220   <td>Solaris</td>
 221   <td>V9 (Ultrasparc)</td>
 222   <td>GCC</td>
 223 </tr>
 224 <tr>
 225   <td>FreeBSD</td>
 226   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 227   <td>GCC</td>
 228 </tr>
 229 <tr>
 230   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 231   <td>PowerPC</td>
 232   <td>GCC</td>
 233 </tr>
 234 <tr>
 235   <td>Cygwin/Win32</td>
 236   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 237   <td>GCC 3.4.X, binutils 2.15</td>
 238 </tr>
 239 <tr>
 240   <td>MinGW/Win32</td>
 241   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a></sup></td>
 242   <td>GCC 3.4.X, binutils 2.15</td>
 243 </tr>
 244 <tr>
 245   <td>Linux</td>
 246   <td>amd64<sup><a href="#pf_3">3</a></sup></td>
 247   <td>GCC</td>
 248 </tr>
 249 </table>
 250
 251 <p>LLVM has partial support for the following platforms:</p>
 252
 253 <table>
 254 <tr>
 255   <th>OS</th>
 256   <th>Arch</th>
 257   <th>Compilers</th>
 258 </tr>
 259 <tr>
 260   <td>Windows</td>
 261   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 262   <td>Visual Studio .NET<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
 263 <tr>
 264   <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
 265   <td>PowerPC</td>
 266   <td>GCC</td>
 267 </tr>
 268 <tr>
 269   <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
 270   <td>PowerPC</td>
 271   <td>GCC</td>
 272 </tr>
 273 </table>
 274
 275 <p><b>Notes:</b></p>
 276
 277 <div class="doc_notes">
 278 <ol>
 279 <li><a name="pf_1">Code generation supported for Pentium processors and
 280 up</a></li>
 281 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
 282 <li><a name="pf_3">No native code generation</a></li>
 283 <li><a name="pf_4">Build is not complete: one or more tools don't link</a></li>
 284 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
 285 <li><a name="pf_6">The port is done using the MSYS shell.
 286 <a href="http://www.mingw.org/MinGWiki/">Download</a> and install
 287 bison (excl. M4.exe) and flex in that order.  Build binutils-2.15 from source,
 288 if necessary.</li>
 289 </ol>
 290 </div>
 291
 292 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
 293 mode, depending on the system (because of all the debug info), and the libraries
 294 appear in more than one of the tools that get linked, so there is some
 295 duplication.  If you do not need many of the tools and you are space-conscious,
 296 you can disable them individually in <tt>llvm/tools/Makefile</tt>.  The Release
 297 build requires considerably less space.</p>
 298
 299 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
 300 guaranteed to do so.  If compilation is successful, the LLVM utilities should be
 301 able to assemble, disassemble, analyze, and optimize LLVM bytecode.  Code
 302 generation should work as well, although the generated native code may not work
 303 on your platform.</p>
 304
 305 <p>The GCC front end is not very portable at the moment.  If you want to get it
 306 to work on another platform, you can download a copy of the source and <a
 307 href="CFEBuildInstrs.html">try to compile it</a> on your platform.</p>
 308
 309 </div>
 310
 311 <!-- ======================================================================= -->
 312 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
 313 <div class="doc_text">
 314   <p>Compiling LLVM requires that you have several software packages
 315   installed. The table below lists those required packages. The Package column
 316   is the usual name for the software package that LLVM depends on. The Version
 317   column provides "known to work" versions of the package. The Notes column
 318   describes how LLVM uses the package and provides other details.</p>
 319   <table>
 320     <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
 321
 322     <tr>
 323       <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
 324       <td>3.79, 3.79.1</td>
 325       <td>Makefile/build processor</td>
 326     </tr>
 327
 328     <tr>
 329       <td><a href="http://gcc.gnu.org">GCC</a></td>
 330       <td>3.4.2</td>
 331       <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
 332     </tr>
 333
 334     <tr>
 335       <td><a href="http://www.gnu.org/software/flex">Flex</a></td>
 336       <td>2.5.4</td>
 337       <td>LEX compiler</td>
 338     </tr>
 339
 340     <tr>
 341       <td><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></td>
 342       <td>1.35</td>
 343       <td>YACC compiler</td>
 344     </tr>
 345
 346     <tr>
 347       <td><a href="https://www.cvshome.org/downloads.html">CVS</a></td>
 348       <td>&ge;1.11</td>
 349       <td>CVS access to LLVM<sup><a href="#sf2">2</a></sup></td>
 350     </tr>
 351
 352     <tr>
 353       <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
 354       <td>1.4.2</td>
 355       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 356     </tr>
 357
 358     <tr>
 359       <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
 360       <td>8.3, 8.4</td>
 361       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 362     </tr>
 363
 364     <tr>
 365       <td><a href="http://expect.nist.gov/">expect</a></td>
 366       <td>5.38.0</td>
 367       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 368     </tr>
 369
 370     <tr>
 371       <td><a href="http://www.perl.com/download.csp">perl</a></td>
 372       <td>&ge;5.6.0</td>
 373       <td>Nightly tester, utilities</td>
 374     </tr>
 375
 376     <tr>
 377       <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
 378       <td>1.4</td>
 379       <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
 380     </tr>
 381
 382     <tr>
 383       <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
 384       <td>2.59</td>
 385       <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
 386     </tr>
 387
 388     <tr>
 389       <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
 390       <td>1.9.2</td>
 391       <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
 392     </tr>
 393
 394     <tr>
 395       <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
 396       <td>1.5.10</td>
 397       <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
 398     </tr>
 399
 400   </table>
 401
 402   <p><b>Notes:</b></p>
 403   <div class="doc_notes">
 404   <ol>
 405     <li><a name="sf3">Only the C and C++ languages are needed so there's no
 406       need to build the other languages for LLVM's purposes.</a> See
 407       <a href="#brokengcc">below</a> for specific version info.</li>
 408     <li><a name="sf2">You only need CVS if you intend to build from the
 409       latest LLVM sources. If you're working from a release distribution, you
 410       don't need CVS.</a></li>
 411     <li><a name="sf3">Only needed if you want to run the automated test
 412       suite in the <tt>llvm/test</tt> directory.</a></li>
 413     <li><a name="sf4">If you want to make changes to the configure scripts,
 414       you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4
 415       or higher). You will also need automake (1.9.2). We only use aclocal
 416       from that package.</a></li>
 417   </ol>
 418   </div>
 419
 420   <p>Additionally, your compilation host is expected to have the usual
 421   plethora of Unix utilities. Specifically:</p>
 422   <ul>
 423     <li><b>ar</b> - archive library builder</li>
 424     <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
 425     <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
 426     <li><b>chmod</b> - change permissions on a file</li>
 427     <li><b>cat</b> - output concatenation utility</li>
 428     <li><b>cp</b> - copy files</li>
 429     <li><b>date</b> - print the current date/time </li>
 430     <li><b>echo</b> - print to standard output</li>
 431     <li><b>egrep</b> - extended regular expression search utility</li>
 432     <li><b>etags</b> - C/C++ tag file creator for vim/emacs</li>
 433     <li><b>find</b> - find files/dirs in a file system</li>
 434     <li><b>grep</b> - regular expression search utility</li>
 435     <li><b>gzip*</b> - gzip command for distribution generation</li>
 436     <li><b>gunzip*</b> - gunzip command for distribution checking</li>
 437     <li><b>install</b> - install directories/files </li>
 438     <li><b>mkdir</b> - create a directory</li>
 439     <li><b>mv</b> - move (rename) files</li>
 440     <li><b>ranlib</b> - symbol table builder for archive libraries</li>
 441     <li><b>rm</b> - remove (delete) files and directories</li>
 442     <li><b>sed</b> - stream editor for transforming output</li>
 443     <li><b>sh</b> - Bourne shell for make build scripts</li>
 444     <li><b>tar</b> - tape archive for distribution generation</li>
 445     <li><b>test</b> - test things in file system</li>
 446     <li><b>unzip*</b> - unzip command for distribution checking</li>
 447     <li><b>zip*</b> - zip command for distribution generation</li>
 448   </ul>
 449 </div>
 450
 451 <!-- ======================================================================= -->
 452 <div class="doc_subsection">
 453   <a name="brokengcc">Broken versions of GCC</a>
 454 </div>
 455
 456 <div class="doc_text">
 457
 458 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
 459 bugs in the compiler.  In particular, several versions of GCC crash when trying
 460 to compile LLVM.  We routinely use GCC 3.3.3 and GCC 3.4.0 and have had success
 461 with them (however, see below).  Other versions of GCC will probably
 462 work as well.  GCC versions listed
 463 here are known to not work.  If you are using one of these versions, please try
 464 to upgrade your GCC to something more recent.  If you run into a problem with a
 465 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
 466 us know</a>.  Please use the "<tt>gcc -v</tt>" command to find out which version
 467 of GCC you are using.
 468 </p>
 469
 470 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
 471 problems in the STL that effectively prevent it from compiling LLVM.
 472 </p>
 473
 474 <p><b>GCC 3.2.2</b>: This version of GCC fails to compile LLVM.</p>
 475
 476 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
 477 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
 478 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
 479
 480 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
 481    Cygwin does not work.  Please <a href="CFEBuildInstrs.html#cygwin">upgrade
 482    to a newer version</a> if possible.</p>
 483 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
 484    possibly others) does not compile LLVM correctly (it appears that exception
 485    handling is broken in some cases).  Please download the FSF 3.3.3 or upgrade
 486    to a newer version of GCC.</p>
 487 </div>
 488
 489
 490
 491 <!-- *********************************************************************** -->
 492 <div class="doc_section">
 493   <a name="starting"><b>Getting Started with LLVM</b></a>
 494 </div>
 495 <!-- *********************************************************************** -->
 496
 497 <div class="doc_text">
 498
 499 <p>The remainder of this guide is meant to get you up and running with
 500 LLVM and to give you some basic information about the LLVM environment.</p>
 501
 502 <p>The later sections of this guide describe the <a
 503 href="#layout">general layout</a> of the the LLVM source tree, a <a
 504 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 505 href="#links">links</a> to find more information about LLVM or to get
 506 help via e-mail.</p>
 507 </div>
 508
 509 <!-- ======================================================================= -->
 510 <div class="doc_subsection">
 511   <a name="terminology">Terminology and Notation</a>
 512 </div>
 513
 514 <div class="doc_text">
 515
 516 <p>Throughout this manual, the following names are used to denote paths
 517 specific to the local system and working environment.  <i>These are not
 518 environment variables you need to set but just strings used in the rest
 519 of this document below</i>.  In any of the examples below, simply replace
 520 each of these names with the appropriate pathname on your local system.
 521 All these paths are absolute:</p>
 522
 523 <dl>
 524     <dt>SRC_ROOT
 525     <dd>
 526     This is the top level directory of the LLVM source tree.
 527     <p>
 528
 529     <dt>OBJ_ROOT
 530     <dd>
 531     This is the top level directory of the LLVM object tree (i.e. the
 532     tree where object files and compiled programs will be placed.  It
 533     can be the same as SRC_ROOT).
 534     <p>
 535
 536     <dt>LLVMGCCDIR
 537     <dd>
 538     This is where the LLVM GCC Front End is installed.
 539     <p>
 540     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 541     <tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
 542 </dl>
 543
 544 </div>
 545
 546 <!-- ======================================================================= -->
 547 <div class="doc_subsection">
 548   <a name="environment">Setting Up Your Environment</a>
 549 </div>
 550
 551 <div class="doc_text">
 552
 553 <p>
 554 In order to compile and use LLVM, you may need to set some environment
 555 variables.
 556
 557 <dl>
 558   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bytecode/libs</tt></dt>
 559   <dd>[Optional] This environment variable helps LLVM linking tools find the
 560   locations of your bytecode libraries. It is provided only a
 561   convenience since you can specify the paths using the -L options of the
 562   tools and the C/C++ front-end will use the bytecode files installed in its
 563   <tt>lib</tt> directory.</dd>
 564 </dl>
 565
 566 </div>
 567
 568 <!-- ======================================================================= -->
 569 <div class="doc_subsection">
 570   <a name="unpack">Unpacking the LLVM Archives</a>
 571 </div>
 572
 573 <div class="doc_text">
 574
 575 <p>
 576 If you have the LLVM distribution, you will need to unpack it before you
 577 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 578 suite and the LLVM GCC front end compiled for your platform.  There is an
 579 additional test suite that is optional.  Each file is a TAR archive that is
 580 compressed with the gzip program.
 581 </p>
 582
 583 <p>The files are as follows, with <em>x.y</em> marking the version number:
 584 <dl>
 585   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 586   <dd>Source release for the LLVM libraries and tools.<br/></dd>
 587
 588   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 589   <dd>Source release for the LLVM test suite.</dd>
 590
 591   <dt><tt>cfrontend-x.y.source.tar.gz</tt></dt>
 592   <dd>Source release of the GCC front end.<br/></dd>
 593
 594   <dt><tt>cfrontend-x.y.sparc-sun-solaris2.8.tar.gz</tt></dt>
 595   <dd>Binary release of the GCC front end for Solaris/Sparc.
 596   <br/></dd>
 597
 598   <dt><tt>cfrontend-x.y.i686-redhat-linux-gnu.tar.gz</tt></dt>
 599   <dd>Binary release of the GCC front end for Linux/x86.<br/></dd>
 600
 601   <dt><tt>cfrontend-x.y.i386-unknown-freebsd5.1.tar.gz</tt></dt>
 602   <dd>Binary release of the GCC front end for FreeBSD/x86.<br/></dd>
 603
 604   <dt><tt>cfrontend-x.y.powerpc-apple-darwin7.6.0.tar.gz</tt></dt>
 605   <dd>Binary release of the GCC front end for MacOS X/PPC.<br/></dd>
 606 </dl>
 607
 608 </div>
 609
 610 <!-- ======================================================================= -->
 611 <div class="doc_subsection">
 612   <a name="checkout">Checkout LLVM from CVS</a>
 613 </div>
 614
 615 <div class="doc_text">
 616
 617 <p>If you have access to our CVS repository, you can get a fresh copy of
 618 the entire source code.  All you need to do is check it out from CVS as
 619 follows:</p>
 620
 621 <ul>
 622 <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 623   <li><tt>cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt>
 624   <li>Hit the return key when prompted for the password.
 625   <li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co
 626       llvm</tt>
 627 </ul>
 628
 629 <p>This will create an '<tt>llvm</tt>' directory in the current
 630 directory and fully populate it with the LLVM source code, Makefiles,
 631 test directories, and local copies of documentation files.</p>
 632
 633 <p>If you want to get a specific release (as opposed to the most recent
 634 revision), you can specify a label.  The following releases have the following
 635 labels:</p>
 636
 637 <ul>
 638 <li>Release 1.4: <b>RELEASE_14</b></li>
 639 <li>Release 1.3: <b>RELEASE_13</b></li>
 640 <li>Release 1.2: <b>RELEASE_12</b></li>
 641 <li>Release 1.1: <b>RELEASE_11</b></li>
 642 <li>Release 1.0: <b>RELEASE_1</b></li>
 643 </ul>
 644
 645 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 646 you get it from the CVS repository:</p>
 647 <pre>
 648   cd llvm/projects
 649   cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-test
 650 </pre>
 651 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 652 configured by the LLVM configure script as well as automatically updated when
 653 you run <tt>cvs update</tt>.</p>
 654
 655 <p>If you would like to get the GCC front end source code, you can also get it
 656 from the CVS repository:</p>
 657
 658 <pre>
 659   cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-gcc
 660 </pre>
 661
 662 <p>Please note that you must follow <a href="CFEBuildInstrs.html">these
 663 instructions</a> to successfully build the LLVM GCC front-end.</p>
 664
 665 </div>
 666
 667 <!-- ======================================================================= -->
 668 <div class="doc_subsubsection">
 669   <a name="mirrors">LLVM CVS Mirrors</a>
 670 </div>
 671
 672 <div class="doc_text">
 673
 674 <p>If the main CVS server is overloaded or inaccessible, you can try one of
 675 these user-hosted mirrors:</p>
 676
 677 <ul>
 678 <li><a href="http://llvm.x10sys.com/">Mirror hosted by eXtensible Systems
 679 Inc.</a></li>
 680 </ul>
 681 </div>
 682
 683 <!-- ======================================================================= -->
 684 <div class="doc_subsection">
 685   <a name="installcf">Install the GCC Front End</a>
 686 </div>
 687
 688 <div class="doc_text">
 689
 690 <p>Before configuring and compiling the LLVM suite, you need to extract the LLVM
 691 GCC front end from the binary distribution.  It is used for building the
 692 bytecode libraries later used by the GCC front end for linking programs, and its
 693 location must be specified when the LLVM suite is configured.</p>
 694
 695 <p>To install the GCC front end, do the following:</p>
 696
 697 <ol>
 698   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 699   <li><tt>gunzip --stdout cfrontend-<i>version</i>.<i>platform</i>.tar.gz | tar -xvf
 700       -</tt></li>
 701 </ol>
 702
 703 <p>Next, you will need to fix your system header files:</p>
 704
 705 <p><tt>cd cfrontend/<i>platform</i><br>
 706    ./fixheaders</tt></p>
 707
 708 <p>The binary versions of the GCC front end may not suit all of your needs.  For
 709 example, the binary distribution may include an old version of a system header
 710 file, not "fix" a header file that needs to be fixed for GCC, or it may be
 711 linked with libraries not available on your system.</p>
 712
 713 <p>In cases like these, you may want to try <a
 714 href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
 715 not for the faint of heart, so be forewarned.</p>
 716
 717 </div>
 718
 719 <!-- ======================================================================= -->
 720 <div class="doc_subsection">
 721   <a name="config">Local LLVM Configuration</a>
 722 </div>
 723
 724 <div class="doc_text">
 725
 726 <p>Once checked out from the CVS repository, the LLVM suite source code must be
 727 configured via the <tt>configure</tt> script.  This script sets variables in the
 728 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 729 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 730 the Makefiles needed to begin building LLVM.</p>
 731
 732 <p>The following environment variables are used by the <tt>configure</tt>
 733 script to configure the build system:</p>
 734
 735 <table>
 736   <tr><th>Variable</th><th>Purpose</th></tr>
 737   <tr>
 738     <td>CC</td>
 739     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 740         <tt>configure</tt> will look for the first GCC C compiler in
 741         <tt>PATH</tt>.  Use this variable to override
 742         <tt>configure</tt>'s default behavior.</td>
 743   </tr>
 744   <tr>
 745     <td>CXX</td>
 746     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 747        <tt>configure</tt> will look for the first GCC C++ compiler in
 748        <tt>PATH</tt>.  Use this variable to override
 749        <tt>configure</tt>'s default behavior.</td>
 750   </tr>
 751 </table>
 752
 753 <p>The following options can be used to set or enable LLVM specific options:</p>
 754
 755 <dl>
 756   <dt><i>--with-llvmgccdir</i></dt>
 757   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 758   The value of this option should specify the full pathname of the C/C++ Front
 759   End to be used. If this option is not provided, the PATH will be searched for
 760   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 761   be inferred from the path found. If the option is not given, and no llvm-gcc
 762   can be found in the path then a warning will be produced by
 763   <tt>configure</tt> indicating this situation. LLVM may still be built with
 764   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 765   will fail as these libraries require llvm-gcc and llvm-g++. See
 766   <a href="#installcf">Install the GCC Front End</a> for details on installing
 767   the C/C++ Front End. See
 768   <a href="CFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 769   for details on building the C/C++ Front End.</dd>
 770   <dt><i>--with-tclinclude</i></dt>
 771   <dd>Path to the tcl include directory under which the <tt>tclsh</tt> can be
 772   found. Use this if you have multiple tcl installations on your machine and you
 773   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 774   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 775   option, the LLVM configure script will search for tcl 8.4 and 8.3 releases.
 776   <p></p>
 777   </dd>
 778   <dt><i>--enable-optimized</i></dt>
 779   <dd>
 780     Enables optimized compilation by default (debugging symbols are removed
 781     and GCC optimization flags are enabled).  The default is to use an
 782     unoptimized build (also known as a debug build).
 783     <p></p>
 784   </dd>
 785   <dt><i>--enable-jit</i></dt>
 786   <dd>
 787     Compile the Just In Time (JIT) compiler functionality.  This is not
 788     available
 789     on all platforms.  The default is dependent on platform, so it is best
 790     to explicitly enable it if you want it.
 791     <p></p>
 792   </dd>
 793   <dt><i>--enable-doxygen</i></dt>
 794   <dd>Look for the doxygen program and enable construction of doxygen based
 795   documentation from the source code. This is disabled by default because
 796   generating the documentation can take a long time and producess 100s of
 797   megabytes of output.</dd>
 798 </dl>
 799
 800 <p>To configure LLVM, follow these steps:</p>
 801
 802 <ol>
 803     <li>Change directory into the object root directory:
 804     <br>
 805     <tt>cd <i>OBJ_ROOT</i></tt>
 806     <p>
 807
 808     <li>Run the <tt>configure</tt> script located in the LLVM source tree:
 809     <br>
 810     <tt><i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</tt>
 811     <p>
 812 </ol>
 813
 814 </div>
 815
 816 <!-- ======================================================================= -->
 817 <div class="doc_subsection">
 818   <a name="compile">Compiling the LLVM Suite Source Code</a>
 819 </div>
 820
 821 <div class="doc_text">
 822
 823 <p>Once you have configured LLVM, you can build it.  There are three types of
 824 builds:</p>
 825
 826 <dl>
 827     <dt>Debug Builds
 828     <dd>
 829     These builds are the default when one types <tt>gmake</tt> (unless the
 830     <tt>--enable-optimized</tt> option was used during configuration).  The
 831     build system will compile the tools and libraries with debugging
 832     information.
 833     <p>
 834
 835     <dt>Release (Optimized) Builds
 836     <dd>
 837     These builds are enabled with the <tt>--enable-optimized</tt> option to
 838     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 839     <tt>gmake</tt> command line.  For these builds, the build system will
 840     compile the tools and libraries with GCC optimizations enabled and strip
 841     debugging information from the libraries and executables it generates.
 842     <p>
 843
 844     <dt>Profile Builds
 845     <dd>
 846     These builds are for use with profiling.  They compile profiling
 847     information into the code for use with programs like <tt>gprof</tt>.
 848     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
 849     on the <tt>gmake</tt> command line.
 850 </dl>
 851
 852 <p>Once you have LLVM configured, you can build it by entering the
 853 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
 854
 855 <p><tt>gmake</tt></p>
 856
 857 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
 858 are using a version of GCC that is known not to compile LLVM.</p>
 859
 860 <p>
 861 If you have multiple processors in your machine, you may wish to use some of
 862 the parallel build options provided by GNU Make.  For example, you could use the
 863 command:</p>
 864
 865 <p><tt>gmake -j2</tt></p>
 866
 867 <p>There are several special targets which are useful when working with the LLVM
 868 source code:</p>
 869
 870 <dl>
 871   <dt><tt>gmake clean</tt>
 872   <dd>
 873   Removes all files generated by the build.  This includes object files,
 874   generated C/C++ files, libraries, and executables.
 875   <p>
 876
 877   <dt><tt>gmake dist-clean</tt>
 878   <dd>
 879   Removes everything that <tt>gmake clean</tt> does, but also removes files
 880   generated by <tt>configure</tt>.  It attempts to return the source tree to the
 881   original state in which it was shipped.
 882   <p>
 883
 884   <dt><tt>gmake install</tt>
 885   <dd>
 886   Installs LLVM header files, libraries, tools, and documentation in a
 887   hierarchy
 888   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
 889   defaults to <tt>/usr/local</tt>.
 890   <p>
 891
 892   <dt><tt>gmake -C runtime install-bytecode</tt>
 893   <dd>
 894   Assuming you built LLVM into $OBJDIR, when this command is run, it will
 895   install bytecode libraries into the GCC front end's bytecode library
 896   directory.  If you need to update your bytecode libraries,
 897   this is the target to use once you've built them.
 898   <p>
 899 </dl>
 900
 901 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
 902 details on these <tt>make</tt> targets and descriptions of other targets
 903 available.</p>
 904
 905 <p>It is also possible to override default values from <tt>configure</tt> by
 906 declaring variables on the command line.  The following are some examples:</p>
 907
 908 <dl>
 909   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
 910   <dd>
 911   Perform a Release (Optimized) build.
 912   <p>
 913
 914   <dt><tt>gmake ENABLE_PROFILING=1</tt>
 915   <dd>
 916   Perform a Profiling build.
 917   <p>
 918
 919   <dt><tt>gmake VERBOSE=1</tt>
 920   <dd>
 921   Print what <tt>gmake</tt> is doing on standard output.
 922   <p>
 923
 924   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
 925   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
 926   the standard output. This also implies <tt>VERBOSE=1</tt>.
 927   <p></dd>
 928 </dl>
 929
 930 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
 931 it and any subdirectories that it contains.  Entering any directory inside the
 932 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
 933 that directory that is out of date.</p>
 934
 935 </div>
 936
 937 <!-- ======================================================================= -->
 938 <div class="doc_subsection">
 939   <a name="objfiles">The Location of LLVM Object Files</a>
 940 </div>
 941
 942 <div class="doc_text">
 943
 944 <p>The LLVM build system is capable of sharing a single LLVM source tree among
 945 several LLVM builds.  Hence, it is possible to build LLVM for several different
 946 platforms or configurations using the same source tree.</p>
 947
 948 <p>This is accomplished in the typical autoconf manner:</p>
 949
 950 <ul>
 951   <li><p>Change directory to where the LLVM object files should live:</p>
 952
 953       <p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
 954
 955   <li><p>Run the <tt>configure</tt> script found in the LLVM source
 956       directory:</p>
 957
 958       <p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
 959 </ul>
 960
 961 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
 962 named after the build type:</p>
 963
 964 <dl>
 965   <dt>Debug Builds
 966   <dd>
 967   <dl>
 968     <dt>Tools
 969     <dd><tt><i>OBJ_ROOT</i>/Debug/bin</tt>
 970     <dt>Libraries
 971     <dd><tt><i>OBJ_ROOT</i>/Debug/lib</tt>
 972   </dl>
 973   <p>
 974
 975   <dt>Release Builds
 976   <dd>
 977   <dl>
 978     <dt>Tools
 979     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
 980     <dt>Libraries
 981     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
 982   </dl>
 983   <p>
 984
 985   <dt>Profile Builds
 986   <dd>
 987   <dl>
 988     <dt>Tools
 989     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
 990     <dt>Libraries
 991     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
 992   </dl>
 993 </dl>
 994
 995 </div>
 996
 997 <!-- ======================================================================= -->
 998 <div class="doc_subsection">
 999   <a name="optionalconfig">Optional Configuration Items</a>
1000 </div>
1001
1002 <div class="doc_text">
1003
1004 <p>
1005 If you're running on a Linux system that supports the "<a
1006   href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">
1007   binfmt_misc</a>"
1008 module, and you have root access on the system, you can set your system up to
1009 execute LLVM bytecode files directly.  To do this, use commands like this (the
1010 first command may not be required if you are already using the module):</p>
1011
1012 <div class="doc_code">
1013 <pre>
1014    $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1015    $ echo ':llvm:M::llvm::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1016    $ chmod u+x hello.bc                (if needed)
1017    $ ./hello.bc
1018 </pre>
1019 </div>
1020
1021 <p>
1022 This allows you to execute LLVM bytecode files directly.  Thanks to Jack
1023 Cummings for pointing this out!
1024 </p>
1025
1026 </div>
1027
1028
1029 <!-- *********************************************************************** -->
1030 <div class="doc_section">
1031   <a name="layout"><b>Program Layout</b></a>
1032 </div>
1033 <!-- *********************************************************************** -->
1034
1035 <div class="doc_text">
1036
1037 <p>One useful source of information about the LLVM source base is the LLVM <a
1038 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1039 href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>.
1040 The following is a brief introduction to code layout:</p>
1041
1042 </div>
1043
1044 <!-- ======================================================================= -->
1045 <div class="doc_subsection"><a name="cvsdir"><tt>CVS</tt> directories</a></div>
1046 <div class="doc_text">
1047 <p>Every directory checked out of CVS will contain a <tt>CVS</tt> directory; for
1048 the most part these can just be ignored.</p>
1049 </div>
1050
1051 <!-- ======================================================================= -->
1052 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1053 <div class="doc_text">
1054   <p>This directory contains some simple examples of how to use the LLVM IR and
1055   JIT.</p>
1056 </div>
1057
1058 <!-- ======================================================================= -->
1059 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1060 <div class="doc_text">
1061
1062 <p>This directory contains public header files exported from the LLVM
1063 library. The three main subdirectories of this directory are:</p>
1064
1065 <dl>
1066   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1067   <dd>This directory contains all of the LLVM specific header files.  This
1068   directory also has subdirectories for different portions of LLVM:
1069   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1070   etc...</dd>
1071
1072   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1073   <dd>This directory contains generic support libraries that are provided with
1074   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1075   and a Command Line option processing library store their header files here.
1076   </dd>
1077
1078   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1079   <dd>This directory contains header files configured by the <tt>configure</tt>
1080   script.  They wrap "standard" UNIX and C header files.  Source code can
1081   include these header files which automatically take care of the conditional
1082   #includes that the <tt>configure</tt> script generates.</dd>
1083 </dl>
1084 </div>
1085
1086 <!-- ======================================================================= -->
1087 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1088 <div class="doc_text">
1089
1090 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1091 almost all code exists in libraries, making it very easy to share code among the
1092 different <a href="#tools">tools</a>.</p>
1093
1094 <dl>
1095   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1096   <dd> This directory holds the core LLVM source files that implement core
1097   classes like Instruction and BasicBlock.</dd>
1098
1099   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1100   <dd>This directory holds the source code for the LLVM assembly language parser
1101   library.</dd>
1102
1103   <dt><tt><b>llvm/lib/ByteCode/</b></tt></dt>
1104   <dd>This directory holds code for reading and write LLVM bytecode.</dd>
1105
1106   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1107   different program analyses, such as Dominator Information, Call Graphs,
1108   Induction Variables, Interval Identification, Natural Loop Identification,
1109   etc.</dd>
1110
1111   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1112   <dd> This directory contains the source code for the LLVM to LLVM program
1113   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1114   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1115   Elimination, and many others.</dd>
1116
1117   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1118   <dd> This directory contains files that describe various target architectures
1119   for code generation.  For example, the <tt>llvm/lib/Target/SparcV9</tt>
1120   directory holds the Sparc machine description while
1121   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter</dd>
1122
1123   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1124   <dd> This directory contains the major parts of the code generator: Instruction
1125   Selector, Instruction Scheduling, and Register Allocation.</dd>
1126
1127   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1128   <dd> This directory contains the source level debugger library that makes
1129   it possible to instrument LLVM programs so that a debugger could identify
1130   source code locations at which the program is executing.</dd>
1131
1132   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1133   <dd> This directory contains libraries for executing LLVM bytecode directly
1134   at runtime in both interpreted and JIT compiled fashions.</dd>
1135
1136   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1137   <dd> This directory contains the source code that corresponds to the header
1138   files located in <tt>llvm/include/Support/</tt>.</dd>
1139
1140   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1141   <dd>This directory contains the operating system abstraction layer that
1142   shields LLVM from platform-specific coding.</dd>
1143 </dl>
1144
1145 </div>
1146
1147 <!-- ======================================================================= -->
1148 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1149 <div class="doc_text">
1150   <p>This directory contains projects that are not strictly part of LLVM but are
1151   shipped with LLVM. This is also the directory where you should create your own
1152   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1153   to set up your own project. See <tt>llvm/projects/Stacker</tt> for a fully
1154   functional example of a compiler front end.</p>
1155 </div>
1156
1157 <!-- ======================================================================= -->
1158 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1159 <div class="doc_text">
1160
1161 <p>This directory contains libraries which are compiled into LLVM bytecode and
1162 used when linking programs with the GCC front end.  Most of these libraries are
1163 skeleton versions of real libraries; for example, libc is a stripped down
1164 version of glibc.</p>
1165
1166 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1167 end to compile.</p>
1168
1169 </div>
1170
1171 <!-- ======================================================================= -->
1172 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1173 <div class="doc_text">
1174   <p>This directory contains feature and regression tests and other basic sanity
1175   checks on the LLVM infrastructure. These are intended to run quickly and cover
1176   a lot of territory without being exhaustive.</p>
1177 </div>
1178
1179 <!-- ======================================================================= -->
1180 <div class="doc_subsection"><a name="llvmtest"><tt>llvm-test</tt></a></div>
1181 <div class="doc_text">
1182   <p>This is not a directory in the normal llvm module; it is a separate CVS
1183   module that must be checked out (usually to <tt>projects/llvm-test</tt>). This
1184   module contains a comprehensive correctness, performance, and benchmarking
1185   test
1186   suite for LLVM. It is a separate CVS module because not every LLVM user is
1187   interested in downloading or building such a comprehensive test. For further
1188   details on this test suite, please see the
1189   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1190 </div>
1191
1192 <!-- ======================================================================= -->
1193 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1194 <div class="doc_text">
1195
1196 <p>The <b>tools</b> directory contains the executables built out of the
1197 libraries above, which form the main part of the user interface.  You can
1198 always get help for a tool by typing <tt>tool_name --help</tt>.  The
1199 following is a brief introduction to the most important tools.  More detailed
1200 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1201
1202 <dl>
1203   <dt><tt><b>analyze</b></tt></dt>
1204   <dd><tt>analyze</tt> is used to run a specific
1205   analysis on an input LLVM bytecode file and print out the results.  It is
1206   primarily useful for debugging analyses, or familiarizing yourself with
1207   what an analysis does.</dd>
1208
1209   <dt><tt><b>bugpoint</b></tt></dt>
1210   <dd><tt>bugpoint</tt> is used to debug
1211   optimization passes or code generation backends by narrowing down the
1212   given test case to the minimum number of passes and/or instructions that
1213   still cause a problem, whether it is a crash or miscompilation. See <a
1214   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1215   on using <tt>bugpoint</tt>.</dd>
1216
1217   <dt><tt><b>llvmc</b></tt></dt>
1218   <dd>The LLVM Compiler Driver. This program can
1219   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1220   pre-processing, translation, optimization, assembly, and linking of programs
1221   all from one command line. <tt>llvmc</tt> also takes care of processing the
1222   dependent libraries found in bytecode. This reduces the need to get the
1223   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1224   note that this tool is new in 1.4 and considered experimental. It will be
1225   fully supported in 1.5.</dd>
1226
1227   <dt><tt><b>llvm-ar</b></tt></dt>
1228   <dd>The archiver produces an archive containing
1229   the given LLVM bytecode files, optionally with an index for faster
1230   lookup.</dd>
1231
1232   <dt><tt><b>llvm-as</b></tt></dt>
1233   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1234   bytecode.</dd>
1235
1236   <dt><tt><b>llvm-dis</b></tt></dt>
1237   <dd>The disassembler transforms the LLVM bytecode to human readable
1238   LLVM assembly.</dd>
1239
1240   <dt><tt><b>llvm-ld</b></tt></dt>
1241   <dd><tt>llvm-ld</tt> is very similar to gccld and provides a general purpose
1242   and extensible linker for LLVM. This is the linker invoked by <tt>llvmc</tt>.
1243   It allows optimization modules to be loaded so that language specific
1244   optimizations can be applied at link time. Please note that this tool is new
1245   in LLVM 1.4 and still considered experimental. It will be fully supported in
1246   LLVM 1.5.</dd>
1247
1248   <dt><tt><b>llvm-link</b></tt></dt>
1249   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1250   a single program.</dd>
1251
1252   <dt><tt><b>lli</b></tt></dt>
1253   <dd><tt>lli</tt> is the LLVM interpreter, which
1254   can directly execute LLVM bytecode (although very slowly...). In addition
1255   to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
1256   specifying <tt>-trace</tt> on the command line). Finally, for
1257   architectures that support it (currently x86, Sparc, and PowerPC), by default,
1258   <tt>lli</tt> will function as a Just-In-Time compiler (if the
1259   functionality was compiled in), and will execute the code <i>much</i>
1260   faster than the interpreter.</dd>
1261
1262   <dt><tt><b>llc</b></tt></dt>
1263   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1264   translates LLVM bytecode to a SPARC or x86 assembly file, or to C code (with
1265   the -march=c option).</dd>
1266
1267   <dt><tt><b>llvm-gcc</b></tt></dt>
1268   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend
1269   that has been retargeted to emit LLVM code as the machine code output.  It
1270   works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
1271   -o</tt> options that are typically used.  The source code for the
1272   <tt>llvm-gcc</tt> tool is currently not included in the LLVM CVS tree
1273   because it is quite large and not very interesting.
1274   <blockquote>
1275     <dl>
1276       <dt><tt><b>gccas</b></tt></dt>
1277       <dd>This tool is invoked by the <tt>llvm-gcc</tt> frontend as the
1278       "assembler" part of the compiler.  This tool actually assembles LLVM
1279       assembly to LLVM bytecode, performs a variety of optimizations, and
1280       outputs LLVM bytecode.  Thus when you invoke
1281       <tt>llvm-gcc -c x.c -o x.o</tt>, you are causing <tt>gccas</tt> to be
1282       run, which writes the <tt>x.o</tt> file (which is an LLVM bytecode file
1283       that can be disassembled or manipulated just like any other bytecode
1284       file).  The command line interface to <tt>gccas</tt> is designed to be
1285       as close as possible to the <b>system</b> `<tt>as</tt>' utility so that
1286       the gcc frontend itself did not have to be modified to interface to
1287       a "weird" assembler.</dd>
1288
1289       <dt><tt><b>gccld</b></tt></dt>
1290       <dd><tt>gccld</tt> links together several LLVM bytecode files into one
1291       bytecode file and does some optimization.  It is the linker invoked by
1292       the GCC frontend when multiple .o files need to be linked together.
1293       Like <tt>gccas</tt>, the command line interface of <tt>gccld</tt> is
1294       designed to match the system linker, to aid interfacing with the GCC
1295       frontend.</dd>
1296     </dl>
1297   </blockquote>
1298   </dd>
1299
1300   <dt><tt><b>opt</b></tt></dt>
1301   <dd><tt>opt</tt> reads LLVM bytecode, applies a
1302   series of LLVM to LLVM transformations (which are specified on the command
1303   line), and then outputs the resultant bytecode.  The '<tt>opt --help</tt>'
1304   command is a good way to get a list of the program transformations
1305   available in LLVM.</dd>
1306 </dl>
1307 </div>
1308
1309 <!-- ======================================================================= -->
1310 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1311 <div class="doc_text">
1312
1313 <p>This directory contains utilities for working with LLVM source code, and some
1314 of the utilities are actually required as part of the build process because they
1315 are code generators for parts of LLVM infrastructure.</p>
1316
1317 <dl>
1318   <dt><tt><b>Burg/</b></tt> <dd><tt>Burg</tt> is an instruction selector
1319   generator -- it builds trees on which it then performs pattern-matching to
1320   select instructions according to the patterns the user has specified. Burg
1321   is currently used in the Sparc V9 backend.<p>
1322
1323   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1324   that finds differences between code that LLC generates and code that LLI
1325   generates. This is a useful tool if you are debugging one of them,
1326   assuming that the other generates correct output. For the full user
1327   manual, run <tt>`perldoc codegen-diff'</tt>.<p>
1328
1329   <dt><tt><b>cvsupdate</b></tt> <dd><tt>cvsupdate</tt> is a script that will
1330   update your CVS tree, but produce a much cleaner and more organized output
1331   than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group
1332   together all the new and updated files and modified files in separate
1333   sections, so you can see at a glance what has changed. If you are at the
1334   top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the
1335   preferred way of updating the tree.<p>
1336
1337   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1338   syntax-highlighting files which will work with Emacs and XEmacs editors,
1339   providing syntax highlighting support for LLVM assembly files and TableGen
1340   description files. For information on how to use the syntax files, consult
1341   the <tt>README</tt> file in that directory.<p>
1342
1343   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1344   and outputs all non-generated source files, which is useful if one wishes
1345   to do a lot of development across directories and does not want to
1346   individually find each file. One way to use it is to run, for example:
1347   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1348   tree.<p>
1349
1350   <dt><tt><b>llvmgrep</b></tt></dt>
1351   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1352   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1353   line. This is a very efficient way of searching the source base for a
1354   particular regular expression.</dd>
1355
1356   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1357   files in the current directory and then compiles and links the tool that
1358   is the first argument. For example, assuming you are in the directory
1359   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1360   simply running <tt>makellvm llc</tt> will make a build of the current
1361   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1362   causing a re-linking of LLC.<p>
1363
1364   <dt><tt><b>NightlyTest.pl</b></tt> and
1365   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1366   cron script to generate nightly status reports of the functionality of
1367   tools, and the results can be seen by following the appropriate link on
1368   the <a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a>.<p>
1369
1370   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1371   the tool used to generate register descriptions, instruction set
1372   descriptions, and even assemblers from common TableGen description
1373   files.<p>
1374
1375   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1376   syntax-highlighting files which will work with the VIM editor, providing
1377   syntax highlighting support for LLVM assembly files and TableGen
1378   description files. For information on how to use the syntax files, consult
1379   the <tt>README</tt> file in that directory.<p>
1380
1381 </dl>
1382
1383 </div>
1384
1385 <!-- ======================================================================= -->
1386 <div class="doc_subsection"><a name="win32"><tt>llvm/win32</tt></a></div>
1387 <div class="doc_text">
1388   <p>This directory contains build scripts and project files for use with
1389   Visual C++. This allows developers on Windows to build LLVM without the need
1390   for Cygwin. The contents of this directory should be considered experimental
1391   at this time.
1392   </p>
1393 </div>
1394 <!-- *********************************************************************** -->
1395 <div class="doc_section">
1396   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1397 </div>
1398 <!-- *********************************************************************** -->
1399
1400 <div class="doc_text">
1401
1402 <ol>
1403   <li>First, create a simple C file, name it 'hello.c':
1404        <pre>
1405    #include &lt;stdio.h&gt;
1406    int main() {
1407      printf("hello world\n");
1408      return 0;
1409    }
1410        </pre></li>
1411
1412   <li><p>Next, compile the C file into a LLVM bytecode file:</p>
1413       <p><tt>% llvm-gcc hello.c -o hello</tt></p>
1414
1415       <p>Note that you should have already built the tools and they have to be
1416       in your path, at least <tt>gccas</tt> and <tt>gccld</tt>.</p>
1417
1418       <p>This will create two result files: <tt>hello</tt> and
1419       <tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
1420       corresponds the the compiled program and the library facilities that it
1421       required.  <tt>hello</tt> is a simple shell script that runs the bytecode
1422       file with <tt>lli</tt>, making the result directly executable.  Note that
1423       all LLVM optimizations are enabled by default, so there is no need for a
1424       "-O3" switch.</p></li>
1425
1426   <li><p>Run the program. To make sure the program ran, execute one of the
1427       following commands:</p>
1428
1429       <p><tt>% ./hello</tt></p>
1430
1431       <p>or</p>
1432
1433       <p><tt>% lli hello.bc</tt></p></li>
1434
1435   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1436       code:</p>
1437
1438       <p><tt>% llvm-dis &lt; hello.bc | less</tt><p></li>
1439
1440   <li><p>Compile the program to native assembly using the LLC code
1441       generator:</p>
1442
1443       <p><tt>% llc hello.bc -o hello.s</tt></p>
1444
1445   <li><p>Assemble the native assembly language file into a program:</p>
1446
1447       <p><b>Solaris:</b><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native</tt></p>
1448       <p><b>Others:</b><tt>% gcc hello.s -o hello.native</tt></p>
1449
1450   <li><p>Execute the native code program:</p>
1451
1452       <p><tt>% ./hello.native</tt></p></li>
1453
1454 </ol>
1455
1456 </div>
1457
1458 <!-- *********************************************************************** -->
1459 <div class="doc_section">
1460   <a name="problems">Common Problems</a>
1461 </div>
1462 <!-- *********************************************************************** -->
1463
1464 <div class="doc_text">
1465
1466 <p>If you are having problems building or using LLVM, or if you have any other
1467 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1468 Asked Questions</a> page.</p>
1469
1470 </div>
1471
1472 <!-- *********************************************************************** -->
1473 <div class="doc_section">
1474   <a name="links">Links</a>
1475 </div>
1476 <!-- *********************************************************************** -->
1477
1478 <div class="doc_text">
1479
1480 <p>This document is just an <b>introduction</b> to how to use LLVM to do
1481 some simple things... there are many more interesting and complicated things
1482 that you can do that aren't documented here (but we'll gladly accept a patch
1483 if you want to write something up!).  For more information about LLVM, check
1484 out:</p>
1485
1486 <ul>
1487   <li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
1488   <li><a href="http://llvm.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
1489   <li><a href="http://llvm.cs.uiuc.edu/docs/Projects.html">Starting a Project
1490   that Uses LLVM</a></li>
1491 </ul>
1492
1493 </div>
1494
1495 <!-- *********************************************************************** -->
1496
1497 <hr>
1498 <address>
1499   <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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1502   src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
1503
1504   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1505   <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1506   <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
1507   Last modified: $Date$
1508 </address>
1509 </body>
1510 </html>