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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></li>
  21       <li><a href="#software">Software</a></li>
  22       <li><a href="#brokengcc">Broken versions of GCC and other tools</a></li>
  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></li>
  28       <li><a href="#environment">Setting Up Your Environment</a></li>
  29       <li><a href="#unpack">Unpacking the LLVM Archives</a></li>
  30       <li><a href="#checkout">Checkout LLVM from Subversion</a></li>
  31       <li><a href="#installcf">Install the GCC Front End</a></li>
  32       <li><a href="#config">Local LLVM Configuration</a></li>
  33       <li><a href="#compile">Compiling the LLVM Suite Source Code</a></li>
  34       <li><a href="#cross-compile">Cross-Compiling LLVM</a></li>
  35       <li><a href="#objfiles">The Location of LLVM Object Files</a></li>
  36       <li><a href="#optionalconfig">Optional Configuration Items</a></li>
  37     </ol></li>
  38
  39   <li><a href="#layout">Program layout</a>
  40     <ol>
  41       <li><a href="#examples"><tt>llvm/examples</tt></a></li>
  42       <li><a href="#include"><tt>llvm/include</tt></a></li>
  43       <li><a href="#lib"><tt>llvm/lib</tt></a></li>
  44       <li><a href="#projects"><tt>llvm/projects</tt></a></li>
  45       <li><a href="#runtime"><tt>llvm/runtime</tt></a></li>
  46       <li><a href="#test"><tt>llvm/test</tt></a></li>
  47       <li><a href="#test-suite"><tt>test-suite</tt></a></li>
  48       <li><a href="#tools"><tt>llvm/tools</tt></a></li>
  49       <li><a href="#utils"><tt>llvm/utils</tt></a></li>
  50     </ol></li>
  51
  52   <li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
  53       <ol>
  54          <li><a href="#tutorial4">Example with llvm-gcc4</a></li>
  55       </ol>
  56   <li><a href="#problems">Common Problems</a>
  57   <li><a href="#links">Links</a>
  58 </ul>
  59
  60 <div class="doc_author">
  61   <p>Written by:
  62     <a href="mailto:criswell@uiuc.edu">John Criswell</a>,
  63     <a href="mailto:sabre@nondot.org">Chris Lattner</a>,
  64     <a href="http://misha.brukman.net">Misha Brukman</a>,
  65     <a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>, and
  66     <a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>.
  67   </p>
  68 </div>
  69
  70
  71 <!-- *********************************************************************** -->
  72 <div class="doc_section">
  73   <a name="overview"><b>Overview</b></a>
  74 </div>
  75 <!-- *********************************************************************** -->
  76
  77 <div class="doc_text">
  78
  79 <p>Welcome to LLVM! In order to get started, you first need to know some
  80 basic information.</p>
  81
  82 <p>First, LLVM comes in three pieces. The first piece is the LLVM
  83 suite. This contains all of the tools, libraries, and header files
  84 needed to use the low level virtual machine.  It contains an
  85 assembler, disassembler, bitcode analyzer and bitcode optimizer.  It
  86 also contains basic regression tests that can be used to test the LLVM
  87 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 Test Suite.  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 llvm-gcc-4.2 front end if you intend to compile C or C++
 118       (see <a href="#installcf">Install the GCC Front End</a> for details):</li>
 119     <ol>
 120       <li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt></li>
 121       <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf -</tt></li>
 122           <li><tt><i>install-binutils-binary-from-MinGW</i></tt> (Windows only)</li>
 123           <li>Note: If the binary extension is "<tt>.bz</tt>" use <tt>bunzip2</tt> instead of <tt>gunzip</tt>.</li>
 124           <li>Note: On Windows, use <a href="http://www.7-zip.org">7-Zip</a> or a similar archiving tool.</li>
 125           <li>Add <tt>llvm-gcc</tt>'s "<tt>bin</tt>" directory to your <tt>PATH</tt> environment variable.</li>
 126     </ol></li>
 127
 128   <li>Get the LLVM Source Code
 129   <ul>
 130     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 131     <ol>
 132       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 133       <li><tt>gunzip --stdout llvm-<i>version</i>.tar.gz | tar -xvf -</tt>
 134     </ol></li>
 135
 136   </ul></li>
 137
 138   <li><b>[Optional]</b> Get the Test Suite Source Code
 139   <ul>
 140     <li>With the distributed files (or use <a href="#checkout">SVN</a>):
 141     <ol>
 142       <li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
 143       <li><tt>cd llvm/projects</tt>
 144       <li><tt>gunzip --stdout llvm-test-<i>version</i>.tar.gz | tar -xvf -</tt>
 145       <li><tt>mv llvm-test-<i>version</i> test-suite</tt>
 146     </ol></li>
 147
 148   </ul></li>
 149
 150
 151   <li>Configure the LLVM Build Environment
 152   <ol>
 153     <li><tt>cd <i>where-you-want-to-build-llvm</i></tt></li>
 154     <li><tt><i>/path/to/llvm/</i>configure [options]</tt><br>
 155     Some common options:
 156
 157       <ul>
 158         <li><tt>--prefix=<i>directory</i></tt>
 159         <p>Specify for <i>directory</i> the full pathname of where you
 160         want the LLVM tools and libraries to be installed (default
 161         <tt>/usr/local</tt>).</p></li>
 162         <li><tt>--with-llvmgccdir=<i>directory</i></tt>
 163         <p>Optionally, specify for <i>directory</i> the full pathname of the
 164         C/C++ front end installation to use with this LLVM configuration. If
 165         not specified, the PATH will be searched.  This is only needed if you
 166         want to run test-suite or do some special kinds of LLVM builds.</p></li>
 167         <li><tt>--enable-spec2000=<i>directory</i></tt>
 168             <p>Enable the SPEC2000 benchmarks for testing.  The SPEC2000
 169             benchmarks should be available in
 170             <tt><i>directory</i></tt>.</p></li>
 171       </ul>
 172   </ol></li>
 173
 174   <li>Build the LLVM Suite:
 175   <ol>
 176       <li><tt>gmake -k |&amp; tee gnumake.out
 177       &nbsp;&nbsp;&nbsp;# this is csh or tcsh syntax</tt></li>
 178       <li>If you get an "internal compiler error (ICE)" or test failures, see
 179           <a href="#brokengcc">below</a>.</li>
 180   </ol>
 181
 182 </ol>
 183
 184 <p>Consult the <a href="#starting">Getting Started with LLVM</a> section for
 185 detailed information on configuring and compiling LLVM.  See <a
 186 href="#environment">Setting Up Your Environment</a> for tips that simplify
 187 working with the GCC front end and LLVM tools.  Go to <a href="#layout">Program
 188 Layout</a> to learn about the layout of the source code tree.</p>
 189
 190 </div>
 191
 192 <!-- *********************************************************************** -->
 193 <div class="doc_section">
 194   <a name="requirements"><b>Requirements</b></a>
 195 </div>
 196 <!-- *********************************************************************** -->
 197
 198 <div class="doc_text">
 199
 200 <p>Before you begin to use the LLVM system, review the requirements given below.
 201 This may save you some trouble by knowing ahead of time what hardware and
 202 software you will need.</p>
 203
 204 </div>
 205
 206 <!-- ======================================================================= -->
 207 <div class="doc_subsection">
 208   <a name="hardware"><b>Hardware</b></a>
 209 </div>
 210
 211 <div class="doc_text">
 212
 213 <p>LLVM is known to work on the following platforms:</p>
 214
 215 <table cellpadding="3" summary="Known LLVM platforms">
 216 <tr>
 217   <th>OS</th>
 218   <th>Arch</th>
 219   <th>Compilers</th>
 220 </tr>
 221 <tr>
 222   <td>AuroraUX</td>
 223   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 224   <td>GCC</td>
 225 </tr>
 226 <tr>
 227   <td>Linux</td>
 228   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 229   <td>GCC</td>
 230 </tr>
 231 <tr>
 232   <td>Linux</td>
 233   <td>amd64</td>
 234   <td>GCC</td>
 235 </tr>
 236 <tr>
 237   <td>Solaris</td>
 238   <td>V9 (Ultrasparc)</td>
 239   <td>GCC</td>
 240 </tr>
 241 <tr>
 242   <td>FreeBSD</td>
 243   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 244   <td>GCC</td>
 245 </tr>
 246 <tr>
 247   <td>FreeBSD</td>
 248   <td>amd64</td>
 249   <td>GCC</td>
 250 </tr>
 251 <tr>
 252   <td>MacOS X<sup><a href="#pf_2">2</a></sup></td>
 253   <td>PowerPC</td>
 254   <td>GCC</td>
 255 </tr>
 256 <tr>
 257   <td>MacOS X<sup><a href="#pf_2">2</a>,<a href="#pf_9">9</a></sup></td>
 258   <td>x86</td>
 259   <td>GCC</td>
 260 </tr>
 261 <tr>
 262   <td>Cygwin/Win32</td>
 263   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_8">8</a>,
 264      <a href="#pf_11">11</a></sup></td>
 265   <td>GCC 3.4.X, binutils 2.20</td>
 266 </tr>
 267 <tr>
 268   <td>MinGW/Win32</td>
 269   <td>x86<sup><a href="#pf_1">1</a>,<a href="#pf_6">6</a>,
 270      <a href="#pf_8">8</a>, <a href="#pf_10">10</a></sup></td>
 271   <td>GCC 3.4.X, binutils 2.20</td>
 272 </tr>
 273 </table>
 274
 275 <p>LLVM has partial support for the following platforms:</p>
 276
 277 <table summary="LLVM partial platform support">
 278 <tr>
 279   <th>OS</th>
 280   <th>Arch</th>
 281   <th>Compilers</th>
 282 </tr>
 283 <tr>
 284   <td>Windows</td>
 285   <td>x86<sup><a href="#pf_1">1</a></sup></td>
 286   <td>Visual Studio 2005 SP1 or higher<sup><a href="#pf_4">4</a>,<a href="#pf_5">5</a></sup></td>
 287 <tr>
 288   <td>AIX<sup><a href="#pf_3">3</a>,<a href="#pf_4">4</a></sup></td>
 289   <td>PowerPC</td>
 290   <td>GCC</td>
 291 </tr>
 292 <tr>
 293   <td>Linux<sup><a href="#pf_3">3</a>,<a href="#pf_5">5</a></sup></td>
 294   <td>PowerPC</td>
 295   <td>GCC</td>
 296 </tr>
 297
 298 <tr>
 299   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 300   <td>Alpha</td>
 301   <td>GCC</td>
 302 </tr>
 303 <tr>
 304   <td>Linux<sup><a href="#pf_7">7</a></sup></td>
 305   <td>Itanium (IA-64)</td>
 306   <td>GCC</td>
 307 </tr>
 308 <tr>
 309   <td>HP-UX<sup><a href="#pf_7">7</a></sup></td>
 310   <td>Itanium (IA-64)</td>
 311   <td>HP aCC</td>
 312 </tr>
 313 </table>
 314
 315 <p><b>Notes:</b></p>
 316
 317 <div class="doc_notes">
 318 <ol>
 319 <li><a name="pf_1">Code generation supported for Pentium processors and
 320 up</a></li>
 321 <li><a name="pf_2">Code generation supported for 32-bit ABI only</a></li>
 322 <li><a name="pf_3">No native code generation</a></li>
 323 <li><a name="pf_4">Build is not complete: one or more tools do not link or function</a></li>
 324 <li><a name="pf_5">The GCC-based C/C++ frontend does not build</a></li>
 325 <li><a name="pf_6">The port is done using the MSYS shell.</a></li>
 326 <li><a name="pf_7">Native code generation exists but is not complete.</a></li>
 327 <li><a name="pf_8">Binutils 2.20 or later is required to build the assembler
 328     generated by LLVM properly.</a></li>
 329 <li><a name="pf_9">XCode 2.5 and gcc 4.0.1</a> (Apple Build 5370) will trip
 330     internal LLVM assert messages when compiled for Release at optimization
 331     levels greater than 0 (i.e., <i>"-O1"</i> and higher).
 332     Add <i>OPTIMIZE_OPTION="-O0"</i> to the build command line
 333     if compiling for LLVM Release or bootstrapping the LLVM toolchain.</li>
 334 <li><a name="pf_10">For MSYS/MinGW on Windows, be sure to install the MSYS
 335     version of the perl package, and be sure it appears in your path
 336     before any Windows-based versions such as Strawberry Perl and
 337     ActivePerl, as these have Windows-specifics that will cause the
 338     build to fail.</a></li>
 339 <li><a name="pf_11">In general, LLVM modules requiring dynamic linking can
 340     not be built on Windows. However, you can build LLVM tools using
 341     <i>"make tools-only"</i>.</li>
 342 </ol>
 343 </div>
 344
 345 <p>Note that you will need about 1-3 GB of space for a full LLVM build in Debug
 346 mode, depending on the system (it is so large because of all the debugging
 347 information and the fact that the libraries are statically linked into multiple
 348 tools).  If you do not need many of the tools and you are space-conscious, you
 349 can pass <tt>ONLY_TOOLS="tools you need"</tt> to make.  The Release build
 350 requires considerably less space.</p>
 351
 352 <p>The LLVM suite <i>may</i> compile on other platforms, but it is not
 353 guaranteed to do so.  If compilation is successful, the LLVM utilities should be
 354 able to assemble, disassemble, analyze, and optimize LLVM bitcode.  Code
 355 generation should work as well, although the generated native code may not work
 356 on your platform.</p>
 357
 358 <p>The GCC front end is not very portable at the moment.  If you want to get it
 359 to work on another platform, you can download a copy of the source and <a
 360 href="GCCFEBuildInstrs.html">try to compile it</a> on your platform.</p>
 361
 362 </div>
 363
 364 <!-- ======================================================================= -->
 365 <div class="doc_subsection"><a name="software"><b>Software</b></a></div>
 366 <div class="doc_text">
 367   <p>Compiling LLVM requires that you have several software packages
 368   installed. The table below lists those required packages. The Package column
 369   is the usual name for the software package that LLVM depends on. The Version
 370   column provides "known to work" versions of the package. The Notes column
 371   describes how LLVM uses the package and provides other details.</p>
 372   <table summary="Packages required to compile LLVM">
 373     <tr><th>Package</th><th>Version</th><th>Notes</th></tr>
 374
 375     <tr>
 376       <td><a href="http://savannah.gnu.org/projects/make">GNU Make</a></td>
 377       <td>3.79, 3.79.1</td>
 378       <td>Makefile/build processor</td>
 379     </tr>
 380
 381     <tr>
 382       <td><a href="http://gcc.gnu.org">GCC</a></td>
 383       <td>3.4.2</td>
 384       <td>C/C++ compiler<sup><a href="#sf1">1</a></sup></td>
 385     </tr>
 386
 387     <tr>
 388       <td><a href="http://www.gnu.org/software/texinfo">TeXinfo</a></td>
 389       <td>4.5</td>
 390       <td>For building the CFE</td>
 391     </tr>
 392
 393     <tr>
 394       <td><a href="http://subversion.tigris.org/project_packages.html">SVN</a></td>
 395       <td>&ge;1.3</td>
 396       <td>Subversion access to LLVM<sup><a href="#sf2">2</a></sup></td>
 397     </tr>
 398
 399     <tr>
 400       <td><a href="http://savannah.gnu.org/projects/dejagnu">DejaGnu</a></td>
 401       <td>1.4.2</td>
 402       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 403     </tr>
 404
 405     <tr>
 406       <td><a href="http://www.tcl.tk/software/tcltk/">tcl</a></td>
 407       <td>8.3, 8.4</td>
 408       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 409     </tr>
 410
 411     <tr>
 412       <td><a href="http://expect.nist.gov/">expect</a></td>
 413       <td>5.38.0</td>
 414       <td>Automated test suite<sup><a href="#sf3">3</a></sup></td>
 415     </tr>
 416
 417     <tr>
 418       <td><a href="http://www.perl.com/download.csp">perl</a></td>
 419       <td>&ge;5.6.0</td>
 420       <td>Nightly tester, utilities</td>
 421     </tr>
 422
 423     <tr>
 424       <td><a href="http://savannah.gnu.org/projects/m4">GNU M4</a>
 425       <td>1.4</td>
 426       <td>Macro processor for configuration<sup><a href="#sf4">4</a></sup></td>
 427     </tr>
 428
 429     <tr>
 430       <td><a href="http://www.gnu.org/software/autoconf">GNU Autoconf</a></td>
 431       <td>2.60</td>
 432       <td>Configuration script builder<sup><a href="#sf4">4</a></sup></td>
 433     </tr>
 434
 435     <tr>
 436       <td><a href="http://www.gnu.org/software/automake">GNU Automake</a></td>
 437       <td>1.9.6</td>
 438       <td>aclocal macro generator<sup><a href="#sf4">4</a></sup></td>
 439     </tr>
 440
 441     <tr>
 442       <td><a href="http://savannah.gnu.org/projects/libtool">libtool</a></td>
 443       <td>1.5.22</td>
 444       <td>Shared library manager<sup><a href="#sf4">4</a></sup></td>
 445     </tr>
 446
 447   </table>
 448
 449   <p><b>Notes:</b></p>
 450   <div class="doc_notes">
 451   <ol>
 452     <li><a name="sf1">Only the C and C++ languages are needed so there's no
 453       need to build the other languages for LLVM's purposes.</a> See
 454       <a href="#brokengcc">below</a> for specific version info.</li>
 455     <li><a name="sf2">You only need Subversion if you intend to build from the
 456       latest LLVM sources. If you're working from a release distribution, you
 457       don't need Subversion.</a></li>
 458     <li><a name="sf3">Only needed if you want to run the automated test
 459       suite in the <tt>llvm/test</tt> directory.</a></li>
 460     <li><a name="sf4">If you want to make changes to the configure scripts,
 461       you will need GNU autoconf (2.60), and consequently, GNU M4 (version 1.4
 462       or higher). You will also need automake (1.9.6). We only use aclocal
 463       from that package.</a></li>
 464   </ol>
 465   </div>
 466
 467   <p>Additionally, your compilation host is expected to have the usual
 468   plethora of Unix utilities. Specifically:</p>
 469   <ul>
 470     <li><b>ar</b> - archive library builder</li>
 471     <li><b>bzip2*</b> - bzip2 command for distribution generation</li>
 472     <li><b>bunzip2*</b> - bunzip2 command for distribution checking</li>
 473     <li><b>chmod</b> - change permissions on a file</li>
 474     <li><b>cat</b> - output concatenation utility</li>
 475     <li><b>cp</b> - copy files</li>
 476     <li><b>date</b> - print the current date/time </li>
 477     <li><b>echo</b> - print to standard output</li>
 478     <li><b>egrep</b> - extended regular expression search utility</li>
 479     <li><b>find</b> - find files/dirs in a file system</li>
 480     <li><b>grep</b> - regular expression search utility</li>
 481     <li><b>gzip*</b> - gzip command for distribution generation</li>
 482     <li><b>gunzip*</b> - gunzip command for distribution checking</li>
 483     <li><b>install</b> - install directories/files </li>
 484     <li><b>mkdir</b> - create a directory</li>
 485     <li><b>mv</b> - move (rename) files</li>
 486     <li><b>ranlib</b> - symbol table builder for archive libraries</li>
 487     <li><b>rm</b> - remove (delete) files and directories</li>
 488     <li><b>sed</b> - stream editor for transforming output</li>
 489     <li><b>sh</b> - Bourne shell for make build scripts</li>
 490     <li><b>tar</b> - tape archive for distribution generation</li>
 491     <li><b>test</b> - test things in file system</li>
 492     <li><b>unzip*</b> - unzip command for distribution checking</li>
 493     <li><b>zip*</b> - zip command for distribution generation</li>
 494   </ul>
 495 </div>
 496
 497 <!-- ======================================================================= -->
 498 <div class="doc_subsection">
 499   <a name="brokengcc">Broken versions of GCC and other tools</a>
 500 </div>
 501
 502 <div class="doc_text">
 503
 504 <p>LLVM is very demanding of the host C++ compiler, and as such tends to expose
 505 bugs in the compiler.  In particular, several versions of GCC crash when trying
 506 to compile LLVM.  We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1
 507 successfully with them (however, see important notes below).  Other versions
 508 of GCC will probably work as well.  GCC versions listed
 509 here are known to not work.  If you are using one of these versions, please try
 510 to upgrade your GCC to something more recent.  If you run into a problem with a
 511 version of GCC not listed here, please <a href="mailto:llvmdev@cs.uiuc.edu">let
 512 us know</a>.  Please use the "<tt>gcc -v</tt>" command to find out which version
 513 of GCC you are using.
 514 </p>
 515
 516 <p><b>GCC versions prior to 3.0</b>: GCC 2.96.x and before had several
 517 problems in the STL that effectively prevent it from compiling LLVM.
 518 </p>
 519
 520 <p><b>GCC 3.2.2 and 3.2.3</b>: These versions of GCC fails to compile LLVM with
 521 a bogus template error.  This was fixed in later GCCs.</p>
 522
 523 <p><b>GCC 3.3.2</b>: This version of GCC suffered from a <a
 524 href="http://gcc.gnu.org/PR13392">serious bug</a> which causes it to crash in
 525 the "<tt>convert_from_eh_region_ranges_1</tt>" GCC function.</p>
 526
 527 <p><b>Cygwin GCC 3.3.3</b>: The version of GCC 3.3.3 commonly shipped with
 528    Cygwin does not work.  Please <a href="GCCFEBuildInstrs.html#cygwin">upgrade
 529    to a newer version</a> if possible.</p>
 530 <p><b>SuSE GCC 3.3.3</b>: The version of GCC 3.3.3 shipped with SuSE 9.1 (and
 531    possibly others) does not compile LLVM correctly (it appears that exception
 532    handling is broken in some cases).  Please download the FSF 3.3.3 or upgrade
 533    to a newer version of GCC.</p>
 534 <p><b>GCC 3.4.0 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 535    code generator, causing an infinite loop in the llvm-gcc build when built
 536    with optimizations enabled (i.e. a release build).</p>
 537 <p><b>GCC 3.4.2 on linux/x86 (32-bit)</b>: GCC miscompiles portions of the
 538    code generator at -O3, as with 3.4.0.  However gcc 3.4.2 (unlike 3.4.0)
 539    correctly compiles LLVM at -O2.  A work around is to build release LLVM
 540    builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."</p>
 541 <p><b>GCC 3.4.x on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1056">
 542    miscompiles portions of LLVM</a>.</p>
 543 <p><b>GCC 3.4.4 (CodeSourcery ARM 2005q3-2)</b>: this compiler miscompiles LLVM
 544    when building with optimizations enabled.  It appears to work with
 545    "<tt>make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1</tt>" or build a debug
 546    build.</p>
 547 <p><b>IA-64 GCC 4.0.0</b>: The IA-64 version of GCC 4.0.0 is known to
 548    miscompile LLVM.</p>
 549 <p><b>Apple Xcode 2.3</b>: GCC crashes when compiling LLVM at -O3 (which is the
 550    default with ENABLE_OPTIMIZED=1.  To work around this, build with
 551    "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".</p>
 552 <p><b>GCC 4.1.1</b>: GCC fails to build LLVM with template concept check errors
 553       compiling some files.  At the time of this writing, GCC mainline (4.2)
 554       did not share the problem.</p>
 555 <p><b>GCC 4.1.1 on X86-64/amd64</b>: GCC <a href="http://llvm.org/PR1063">
 556    miscompiles portions of LLVM</a> when compiling llvm itself into 64-bit
 557    code.  LLVM will appear to mostly work but will be buggy, e.g. failing
 558    portions of its testsuite.</p>
 559 <p><b>GCC 4.1.2 on OpenSUSE</b>: Seg faults during libstdc++ build and on x86_64
 560 platforms compiling md5.c gets a mangled constant.</p>
 561 <p><b>GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian</b>: Appears
 562 to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining
 563 about symbols remaining in the table on destruction.</p>
 564 <p><b>GCC 4.1.2 20071124 (Red Hat 4.1.2-42)</b>: Suffers from the same symptoms
 565 as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).</p>
 566 <p><b>Cygwin GCC 4.3.2 20080827 (beta) 2</b>:
 567   Users <a href="http://llvm.org/PR4145">reported</a> various problems related
 568   with link errors when using this GCC version.</p>
 569 <p><b>Debian GCC 4.3.2 on X86</b>: Crashes building some files in LLVM 2.6.</p>
 570 <p><b>GCC 4.3.3 (Debian 4.3.3-10) on ARM</b>: Miscompiles parts of LLVM 2.6
 571 when optimizations are turned on. The symptom is an infinite loop in
 572 FoldingSetImpl::RemoveNode while running the code generator.</p>
 573 <p><b>GCC 4.3.5 and GCC 4.4.5 on ARM</b>: These can miscompile <tt>value >>
 574 1</tt> even at -O0. A test failure in <tt>test/Assembler/alignstack.ll</tt> is
 575 one symptom of the problem.
 576 <p><b>GNU ld 2.16.X</b>. Some 2.16.X versions of the ld linker will produce very
 577 long warning messages complaining that some ".gnu.linkonce.t.*" symbol was
 578 defined in a discarded section. You can safely ignore these messages as they are
 579 erroneous and the linkage is correct.  These messages disappear using ld
 580 2.17.</p>
 581
 582 <p><b>GNU binutils 2.17</b>: Binutils 2.17 contains <a
 583 href="http://sourceware.org/bugzilla/show_bug.cgi?id=3111">a bug</a> which
 584 causes huge link times (minutes instead of seconds) when building LLVM.  We
 585 recommend upgrading to a newer version (2.17.50.0.4 or later).</p>
 586
 587 <p><b>GNU Binutils 2.19.1 Gold</b>: This version of Gold contained
 588 <a href="http://sourceware.org/bugzilla/show_bug.cgi?id=9836">a bug</a>
 589 which causes intermittent failures when building LLVM with position independent
 590 code.  The symptom is an error about cyclic dependencies.  We recommend
 591 upgrading to a newer version of Gold.</p>
 592
 593 </div>
 594
 595
 596
 597 <!-- *********************************************************************** -->
 598 <div class="doc_section">
 599   <a name="starting"><b>Getting Started with LLVM</b></a>
 600 </div>
 601 <!-- *********************************************************************** -->
 602
 603 <div class="doc_text">
 604
 605 <p>The remainder of this guide is meant to get you up and running with
 606 LLVM and to give you some basic information about the LLVM environment.</p>
 607
 608 <p>The later sections of this guide describe the <a
 609 href="#layout">general layout</a> of the the LLVM source tree, a <a
 610 href="#tutorial">simple example</a> using the LLVM tool chain, and <a
 611 href="#links">links</a> to find more information about LLVM or to get
 612 help via e-mail.</p>
 613 </div>
 614
 615 <!-- ======================================================================= -->
 616 <div class="doc_subsection">
 617   <a name="terminology">Terminology and Notation</a>
 618 </div>
 619
 620 <div class="doc_text">
 621
 622 <p>Throughout this manual, the following names are used to denote paths
 623 specific to the local system and working environment.  <i>These are not
 624 environment variables you need to set but just strings used in the rest
 625 of this document below</i>.  In any of the examples below, simply replace
 626 each of these names with the appropriate pathname on your local system.
 627 All these paths are absolute:</p>
 628
 629 <dl>
 630     <dt>SRC_ROOT
 631     <dd>
 632     This is the top level directory of the LLVM source tree.
 633     <br><br>
 634
 635     <dt>OBJ_ROOT
 636     <dd>
 637     This is the top level directory of the LLVM object tree (i.e. the
 638     tree where object files and compiled programs will be placed.  It
 639     can be the same as SRC_ROOT).
 640     <br><br>
 641
 642     <dt>LLVMGCCDIR
 643     <dd>
 644     This is where the LLVM GCC Front End is installed.
 645     <p>
 646     For the pre-built GCC front end binaries, the LLVMGCCDIR is
 647     <tt>llvm-gcc/<i>platform</i>/llvm-gcc</tt>.
 648 </dl>
 649
 650 </div>
 651
 652 <!-- ======================================================================= -->
 653 <div class="doc_subsection">
 654   <a name="environment">Setting Up Your Environment</a>
 655 </div>
 656
 657 <div class="doc_text">
 658
 659 <p>
 660 In order to compile and use LLVM, you may need to set some environment
 661 variables.
 662
 663 <dl>
 664   <dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt>/path/to/your/bitcode/libs</tt></dt>
 665   <dd>[Optional] This environment variable helps LLVM linking tools find the
 666   locations of your bitcode libraries. It is provided only as a
 667   convenience since you can specify the paths using the -L options of the
 668   tools and the C/C++ front-end will automatically use the bitcode files
 669   installed in its
 670   <tt>lib</tt> directory.</dd>
 671 </dl>
 672
 673 </div>
 674
 675 <!-- ======================================================================= -->
 676 <div class="doc_subsection">
 677   <a name="unpack">Unpacking the LLVM Archives</a>
 678 </div>
 679
 680 <div class="doc_text">
 681
 682 <p>
 683 If you have the LLVM distribution, you will need to unpack it before you
 684 can begin to compile it.  LLVM is distributed as a set of two files: the LLVM
 685 suite and the LLVM GCC front end compiled for your platform.  There is an
 686 additional test suite that is optional.  Each file is a TAR archive that is
 687 compressed with the gzip program.
 688 </p>
 689
 690 <p>The files are as follows, with <em>x.y</em> marking the version number:
 691 <dl>
 692   <dt><tt>llvm-x.y.tar.gz</tt></dt>
 693   <dd>Source release for the LLVM libraries and tools.<br></dd>
 694
 695   <dt><tt>llvm-test-x.y.tar.gz</tt></dt>
 696   <dd>Source release for the LLVM test-suite.</dd>
 697
 698   <dt><tt>llvm-gcc-4.2-x.y.source.tar.gz</tt></dt>
 699   <dd>Source release of the llvm-gcc-4.2 front end.  See README.LLVM in the root
 700       directory for build instructions.<br></dd>
 701
 702   <dt><tt>llvm-gcc-4.2-x.y-platform.tar.gz</tt></dt>
 703   <dd>Binary release of the llvm-gcc-4.2 front end for a specific platform.<br></dd>
 704
 705 </dl>
 706
 707 </div>
 708
 709 <!-- ======================================================================= -->
 710 <div class="doc_subsection">
 711   <a name="checkout">Checkout LLVM from Subversion</a>
 712 </div>
 713
 714 <div class="doc_text">
 715
 716 <p>If you have access to our Subversion repository, you can get a fresh copy of
 717 the entire source code.  All you need to do is check it out from Subversion as
 718 follows:</p>
 719
 720 <ul>
 721   <li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
 722   <li>Read-Only: <tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li>
 723   <li>Read-Write:<tt>svn co https://user@llvm.org/svn/llvm-project/llvm/trunk
 724     llvm</tt></li>
 725 </ul>
 726
 727
 728 <p>This will create an '<tt>llvm</tt>' directory in the current
 729 directory and fully populate it with the LLVM source code, Makefiles,
 730 test directories, and local copies of documentation files.</p>
 731
 732 <p>If you want to get a specific release (as opposed to the most recent
 733 revision), you can checkout it from the '<tt>tags</tt>' directory (instead of
 734 '<tt>trunk</tt>'). The following releases are located in the following
 735 subdirectories of the '<tt>tags</tt>' directory:</p>
 736
 737 <ul>
 738 <li>Release 2.8: <b>RELEASE_28</b></li>
 739 <li>Release 2.7: <b>RELEASE_27</b></li>
 740 <li>Release 2.6: <b>RELEASE_26</b></li>
 741 <li>Release 2.5: <b>RELEASE_25</b></li>
 742 <li>Release 2.4: <b>RELEASE_24</b></li>
 743 <li>Release 2.3: <b>RELEASE_23</b></li>
 744 <li>Release 2.2: <b>RELEASE_22</b></li>
 745 <li>Release 2.1: <b>RELEASE_21</b></li>
 746 <li>Release 2.0: <b>RELEASE_20</b></li>
 747 <li>Release 1.9: <b>RELEASE_19</b></li>
 748 <li>Release 1.8: <b>RELEASE_18</b></li>
 749 <li>Release 1.7: <b>RELEASE_17</b></li>
 750 <li>Release 1.6: <b>RELEASE_16</b></li>
 751 <li>Release 1.5: <b>RELEASE_15</b></li>
 752 <li>Release 1.4: <b>RELEASE_14</b></li>
 753 <li>Release 1.3: <b>RELEASE_13</b></li>
 754 <li>Release 1.2: <b>RELEASE_12</b></li>
 755 <li>Release 1.1: <b>RELEASE_11</b></li>
 756 <li>Release 1.0: <b>RELEASE_1</b></li>
 757 </ul>
 758
 759 <p>If you would like to get the LLVM test suite (a separate package as of 1.4),
 760 you get it from the Subversion repository:</p>
 761
 762 <div class="doc_code">
 763 <pre>
 764 % cd llvm/projects
 765 % svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite
 766 </pre>
 767 </div>
 768
 769 <p>By placing it in the <tt>llvm/projects</tt>, it will be automatically
 770 configured by the LLVM configure script as well as automatically updated when
 771 you run <tt>svn update</tt>.</p>
 772
 773 <p>If you would like to get the GCC front end source code, you can also get it
 774 and build it yourself.  Please follow <a href="GCCFEBuildInstrs.html">these
 775 instructions</a> to successfully get and build the LLVM GCC front-end.</p>
 776
 777 </div>
 778
 779 <!-- ======================================================================= -->
 780 <div class="doc_subsection">
 781   <a name="installcf">Install the GCC Front End</a>
 782 </div>
 783
 784 <div class="doc_text">
 785
 786 <p>Before configuring and compiling the LLVM suite (or if you want to use just the LLVM
 787 GCC front end) you can optionally extract the front end from the binary distribution.
 788 It is used for running the LLVM test-suite and for compiling C/C++ programs.  Note that
 789 you can optionally <a href="GCCFEBuildInstrs.html">build llvm-gcc yourself</a> after building the
 790 main LLVM repository.</p>
 791
 792 <p>To install the GCC front end, do the following (on Windows, use an archival tool
 793 like <a href="http://www.7-zip.org">7-zip</a> that understands gzipped tars):</p>
 794
 795 <ol>
 796   <li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
 797   <li><tt>gunzip --stdout llvm-gcc-4.2-<i>version</i>-<i>platform</i>.tar.gz | tar -xvf
 798       -</tt></li>
 799 </ol>
 800
 801 <p>Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for
 802 <tt>llvm-gcc</tt> and <tt>llvm-g++</tt> to some directory in your path.  If you're using a
 803 Windows-based system, add the <tt>bin</tt> subdirectory of your front end installation directory
 804 to your <tt>PATH</tt> environment variable.  For example, if you uncompressed the binary to
 805 <tt>c:\llvm-gcc</tt>, add <tt>c:\llvm-gcc\bin</tt> to your <tt>PATH</tt>.</p>
 806
 807 <p>If you now want to build LLVM from source, when you configure LLVM, it will
 808 automatically detect <tt>llvm-gcc</tt>'s presence (if it is in your path) enabling its
 809 use in test-suite.  Note that you can always build or install <tt>llvm-gcc</tt> at any
 810 point after building the main LLVM repository: just reconfigure llvm and
 811 test-suite will pick it up.
 812 </p>
 813
 814 <p>As a convenience for Windows users, the front end binaries for MinGW/x86 include
 815 versions of the required w32api and mingw-runtime binaries.  The last remaining step for
 816 Windows users is to simply uncompress the binary binutils package from
 817 <a href="http://mingw.org/">MinGW</a> into your front end installation directory.  While the
 818 front end installation steps are not quite the same as a typical manual MinGW installation,
 819 they should be similar enough to those who have previously installed MinGW on Windows systems.</p>
 820
 821 <p>To install binutils on Windows:</p>
 822
 823 <ol>
 824   <li><tt><i>download GNU Binutils from <a href="http://sourceforge.net/projects/mingw/files/">MinGW Downloads</a></i></tt></li>
 825   <li><tt>cd <i>where-you-uncompressed-the-front-end</i></tt></li>
 826   <li><tt><i>uncompress archived binutils directories (not the tar file) into the current directory</i></tt></li>
 827 </ol>
 828
 829 <p>The binary versions of the LLVM GCC front end may not suit all of your needs.  For
 830 example, the binary distribution may include an old version of a system header
 831 file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with
 832 libraries not available on your system.  In cases like these, you may want to try
 833 <a href="GCCFEBuildInstrs.html">building the GCC front end from source</a>.  Thankfully,
 834 this is much easier now than it was in the past.</p>
 835
 836 <p>We also do not currently support updating of the GCC front end by manually overlaying
 837 newer versions of the w32api and mingw-runtime binary packages that may become available
 838 from MinGW.  At this time, it's best to think of the MinGW LLVM GCC front end binary as
 839 a self-contained convenience package that requires Windows users to simply download and
 840 uncompress the GNU Binutils binary package from the MinGW project.</p>
 841
 842 <p>Regardless of your platform, if you discover that installing the LLVM GCC front end
 843 binaries is not as easy as previously described, or you would like to suggest improvements,
 844 please let us know how you would like to see things improved by dropping us a note on our
 845 <a href="http://llvm.org/docs/#maillist">mailing list</a>.</p>
 846
 847 </div>
 848
 849 <!-- ======================================================================= -->
 850 <div class="doc_subsection">
 851   <a name="config">Local LLVM Configuration</a>
 852 </div>
 853
 854 <div class="doc_text">
 855
 856   <p>Once checked out from the Subversion repository, the LLVM suite source
 857   code must be
 858 configured via the <tt>configure</tt> script.  This script sets variables in the
 859 various <tt>*.in</tt> files, most notably <tt>llvm/Makefile.config</tt> and
 860 <tt>llvm/include/Config/config.h</tt>.  It also populates <i>OBJ_ROOT</i> with
 861 the Makefiles needed to begin building LLVM.</p>
 862
 863 <p>The following environment variables are used by the <tt>configure</tt>
 864 script to configure the build system:</p>
 865
 866 <table summary="LLVM configure script environment variables">
 867   <tr><th>Variable</th><th>Purpose</th></tr>
 868   <tr>
 869     <td>CC</td>
 870     <td>Tells <tt>configure</tt> which C compiler to use.  By default,
 871         <tt>configure</tt> will look for the first GCC C compiler in
 872         <tt>PATH</tt>.  Use this variable to override
 873         <tt>configure</tt>'s default behavior.</td>
 874   </tr>
 875   <tr>
 876     <td>CXX</td>
 877     <td>Tells <tt>configure</tt> which C++ compiler to use.  By default,
 878        <tt>configure</tt> will look for the first GCC C++ compiler in
 879        <tt>PATH</tt>.  Use this variable to override
 880        <tt>configure</tt>'s default behavior.</td>
 881   </tr>
 882 </table>
 883
 884 <p>The following options can be used to set or enable LLVM specific options:</p>
 885
 886 <dl>
 887   <dt><i>--with-llvmgccdir</i></dt>
 888   <dd>Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration.
 889   The value of this option should specify the full pathname of the C/C++ Front
 890   End to be used. If this option is not provided, the PATH will be searched for
 891   a program named <i>llvm-gcc</i> and the C/C++ FrontEnd install directory will
 892   be inferred from the path found. If the option is not given, and no llvm-gcc
 893   can be found in the path then a warning will be produced by
 894   <tt>configure</tt> indicating this situation. LLVM may still be built with
 895   the <tt>tools-only</tt> target but attempting to build the runtime libraries
 896   will fail as these libraries require llvm-gcc and llvm-g++. See
 897   <a href="#installcf">Install the GCC Front End</a> for details on installing
 898   the C/C++ Front End. See
 899   <a href="GCCFEBuildInstrs.html">Bootstrapping the LLVM C/C++ Front-End</a>
 900   for details on building the C/C++ Front End.</dd>
 901   <dt><i>--with-tclinclude</i></dt>
 902   <dd>Path to the tcl include directory under which <tt>tclsh</tt> can be
 903   found. Use this if you have multiple tcl installations on your machine and you
 904   want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the
 905   dejagnu based test suite in <tt>llvm/test</tt>. If you don't specify this
 906   option, the LLVM configure script will search for the tcl 8.4 and 8.3
 907   releases.
 908   <br><br>
 909   </dd>
 910   <dt><i>--enable-optimized</i></dt>
 911   <dd>
 912     Enables optimized compilation (debugging symbols are removed
 913     and GCC optimization flags are enabled). Note that this is the default
 914     setting     if you are using the LLVM distribution. The default behavior
 915     of an Subversion checkout is to use an unoptimized build (also known as a
 916     debug build).
 917     <br><br>
 918   </dd>
 919   <dt><i>--enable-debug-runtime</i></dt>
 920   <dd>
 921     Enables debug symbols in the runtime libraries. The default is to strip
 922     debug symbols from the runtime libraries.
 923   </dd>
 924   <dt><i>--enable-jit</i></dt>
 925   <dd>
 926     Compile the Just In Time (JIT) compiler functionality.  This is not
 927     available
 928     on all platforms.  The default is dependent on platform, so it is best
 929     to explicitly enable it if you want it.
 930     <br><br>
 931   </dd>
 932   <dt><i>--enable-targets=</i><tt>target-option</tt></dt>
 933   <dd>Controls which targets will be built and linked into llc. The default
 934   value for <tt>target_options</tt> is "all" which builds and links all
 935   available targets.  The value "host-only" can be specified to build only a
 936   native compiler (no cross-compiler targets available). The "native" target is
 937   selected as the target of the build host. You can also specify a comma
 938   separated list of target names that you want available in llc. The target
 939   names use all lower case. The current set of targets is: <br>
 940   <tt>alpha, ia64, powerpc, skeleton, sparc, x86</tt>.
 941   <br><br></dd>
 942   <dt><i>--enable-doxygen</i></dt>
 943   <dd>Look for the doxygen program and enable construction of doxygen based
 944   documentation from the source code. This is disabled by default because
 945   generating the documentation can take a long time and producess 100s of
 946   megabytes of output.</dd>
 947   <dt><i>--with-udis86</i></dt>
 948   <dd>LLVM can use external disassembler library for various purposes (now it's
 949   used only for examining code produced by JIT). This option will enable usage
 950   of <a href="http://udis86.sourceforge.net/">udis86</a> x86 (both 32 and 64
 951   bits) disassembler library.</dd>
 952 </dl>
 953
 954 <p>To configure LLVM, follow these steps:</p>
 955
 956 <ol>
 957     <li><p>Change directory into the object root directory:</p>
 958
 959     <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
 960
 961     <li><p>Run the <tt>configure</tt> script located in the LLVM source
 962     tree:</p>
 963
 964     <div class="doc_code">
 965     <pre>% <i>SRC_ROOT</i>/configure --prefix=/install/path [other options]</pre>
 966     </div></li>
 967 </ol>
 968
 969 </div>
 970
 971 <!-- ======================================================================= -->
 972 <div class="doc_subsection">
 973   <a name="compile">Compiling the LLVM Suite Source Code</a>
 974 </div>
 975
 976 <div class="doc_text">
 977
 978 <p>Once you have configured LLVM, you can build it.  There are three types of
 979 builds:</p>
 980
 981 <dl>
 982     <dt>Debug Builds
 983     <dd>
 984     These builds are the default when one is using an Subversion checkout and
 985     types <tt>gmake</tt> (unless the <tt>--enable-optimized</tt> option was
 986     used during configuration).  The build system will compile the tools and
 987     libraries with debugging information.  To get a Debug Build using the
 988     LLVM distribution the <tt>--disable-optimized</tt> option must be passed
 989     to <tt>configure</tt>.
 990     <br><br>
 991
 992     <dt>Release (Optimized) Builds
 993     <dd>
 994     These builds are enabled with the <tt>--enable-optimized</tt> option to
 995     <tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
 996     <tt>gmake</tt> command line.  For these builds, the build system will
 997     compile the tools and libraries with GCC optimizations enabled and strip
 998     debugging information from the libraries and executables it generates.
 999     Note that Release Builds are default when using an LLVM distribution.
1000     <br><br>
1001
1002     <dt>Profile Builds
1003     <dd>
1004     These builds are for use with profiling.  They compile profiling
1005     information into the code for use with programs like <tt>gprof</tt>.
1006     Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
1007     on the <tt>gmake</tt> command line.
1008 </dl>
1009
1010 <p>Once you have LLVM configured, you can build it by entering the
1011 <i>OBJ_ROOT</i> directory and issuing the following command:</p>
1012
1013 <div class="doc_code"><pre>% gmake</pre></div>
1014
1015 <p>If the build fails, please <a href="#brokengcc">check here</a> to see if you
1016 are using a version of GCC that is known not to compile LLVM.</p>
1017
1018 <p>
1019 If you have multiple processors in your machine, you may wish to use some of
1020 the parallel build options provided by GNU Make.  For example, you could use the
1021 command:</p>
1022
1023 <div class="doc_code"><pre>% gmake -j2</pre></div>
1024
1025 <p>There are several special targets which are useful when working with the LLVM
1026 source code:</p>
1027
1028 <dl>
1029   <dt><tt>gmake clean</tt>
1030   <dd>
1031   Removes all files generated by the build.  This includes object files,
1032   generated C/C++ files, libraries, and executables.
1033   <br><br>
1034
1035   <dt><tt>gmake dist-clean</tt>
1036   <dd>
1037   Removes everything that <tt>gmake clean</tt> does, but also removes files
1038   generated by <tt>configure</tt>.  It attempts to return the source tree to the
1039   original state in which it was shipped.
1040   <br><br>
1041
1042   <dt><tt>gmake install</tt>
1043   <dd>
1044   Installs LLVM header files, libraries, tools, and documentation in a
1045   hierarchy
1046   under $PREFIX, specified with <tt>./configure --prefix=[dir]</tt>, which
1047   defaults to <tt>/usr/local</tt>.
1048   <br><br>
1049
1050   <dt><tt>gmake -C runtime install-bytecode</tt>
1051   <dd>
1052   Assuming you built LLVM into $OBJDIR, when this command is run, it will
1053   install bitcode libraries into the GCC front end's bitcode library
1054   directory.  If you need to update your bitcode libraries,
1055   this is the target to use once you've built them.
1056   <br><br>
1057 </dl>
1058
1059 <p>Please see the <a href="MakefileGuide.html">Makefile Guide</a> for further
1060 details on these <tt>make</tt> targets and descriptions of other targets
1061 available.</p>
1062
1063 <p>It is also possible to override default values from <tt>configure</tt> by
1064 declaring variables on the command line.  The following are some examples:</p>
1065
1066 <dl>
1067   <dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
1068   <dd>
1069   Perform a Release (Optimized) build.
1070   <br><br>
1071
1072   <dt><tt>gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1</tt>
1073   <dd>
1074   Perform a Release (Optimized) build without assertions enabled.
1075   <br><br>
1076
1077   <dt><tt>gmake ENABLE_OPTIMIZED=0</tt>
1078   <dd>
1079   Perform a Debug build.
1080   <br><br>
1081
1082   <dt><tt>gmake ENABLE_PROFILING=1</tt>
1083   <dd>
1084   Perform a Profiling build.
1085   <br><br>
1086
1087   <dt><tt>gmake VERBOSE=1</tt>
1088   <dd>
1089   Print what <tt>gmake</tt> is doing on standard output.
1090   <br><br>
1091
1092   <dt><tt>gmake TOOL_VERBOSE=1</tt></dt>
1093   <dd>Ask each tool invoked by the makefiles to print out what it is doing on
1094   the standard output. This also implies <tt>VERBOSE=1</tt>.
1095   <br><br></dd>
1096 </dl>
1097
1098 <p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
1099 it and any subdirectories that it contains.  Entering any directory inside the
1100 LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
1101 that directory that is out of date.</p>
1102
1103 </div>
1104
1105 <!-- ======================================================================= -->
1106 <div class="doc_subsection">
1107   <a name="cross-compile">Cross-Compiling LLVM</a>
1108 </div>
1109
1110 <div class="doc_text">
1111   <p>It is possible to cross-compile LLVM itself. That is, you can create LLVM
1112   executables and libraries to be hosted on a platform different from the
1113   platform where they are build (a Canadian Cross build). To configure a
1114   cross-compile, supply the configure script with <tt>--build</tt> and
1115   <tt>--host</tt> options that are different. The values of these options must
1116   be legal target triples that your GCC compiler supports.</p>
1117
1118   <p>The result of such a build is executables that are not runnable on
1119   on the build host (--build option) but can be executed on the compile host
1120   (--host option).</p>
1121 </div>
1122
1123 <!-- ======================================================================= -->
1124 <div class="doc_subsection">
1125   <a name="objfiles">The Location of LLVM Object Files</a>
1126 </div>
1127
1128 <div class="doc_text">
1129
1130 <p>The LLVM build system is capable of sharing a single LLVM source tree among
1131 several LLVM builds.  Hence, it is possible to build LLVM for several different
1132 platforms or configurations using the same source tree.</p>
1133
1134 <p>This is accomplished in the typical autoconf manner:</p>
1135
1136 <ul>
1137   <li><p>Change directory to where the LLVM object files should live:</p>
1138
1139       <div class="doc_code"><pre>% cd <i>OBJ_ROOT</i></pre></div></li>
1140
1141   <li><p>Run the <tt>configure</tt> script found in the LLVM source
1142       directory:</p>
1143
1144       <div class="doc_code"><pre>% <i>SRC_ROOT</i>/configure</pre></div></li>
1145 </ul>
1146
1147 <p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
1148 named after the build type:</p>
1149
1150 <dl>
1151   <dt>Debug Builds with assertions enabled (the default)
1152   <dd>
1153   <dl>
1154     <dt>Tools
1155     <dd><tt><i>OBJ_ROOT</i>/Debug+Asserts/bin</tt>
1156     <dt>Libraries
1157     <dd><tt><i>OBJ_ROOT</i>/Debug+Asserts/lib</tt>
1158   </dl>
1159   <br><br>
1160
1161   <dt>Release Builds
1162   <dd>
1163   <dl>
1164     <dt>Tools
1165     <dd><tt><i>OBJ_ROOT</i>/Release/bin</tt>
1166     <dt>Libraries
1167     <dd><tt><i>OBJ_ROOT</i>/Release/lib</tt>
1168   </dl>
1169   <br><br>
1170
1171   <dt>Profile Builds
1172   <dd>
1173   <dl>
1174     <dt>Tools
1175     <dd><tt><i>OBJ_ROOT</i>/Profile/bin</tt>
1176     <dt>Libraries
1177     <dd><tt><i>OBJ_ROOT</i>/Profile/lib</tt>
1178   </dl>
1179 </dl>
1180
1181 </div>
1182
1183 <!-- ======================================================================= -->
1184 <div class="doc_subsection">
1185   <a name="optionalconfig">Optional Configuration Items</a>
1186 </div>
1187
1188 <div class="doc_text">
1189
1190 <p>
1191 If you're running on a Linux system that supports the "<a
1192 href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">binfmt_misc</a>"
1193 module, and you have root access on the system, you can set your system up to
1194 execute LLVM bitcode files directly. To do this, use commands like this (the
1195 first command may not be required if you are already using the module):</p>
1196
1197 <div class="doc_code">
1198 <pre>
1199 $ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
1200 $ echo ':llvm:M::BC::/path/to/lli:' &gt; /proc/sys/fs/binfmt_misc/register
1201 $ chmod u+x hello.bc   (if needed)
1202 $ ./hello.bc
1203 </pre>
1204 </div>
1205
1206 <p>
1207 This allows you to execute LLVM bitcode files directly.  On Debian, you
1208 can also use this command instead of the 'echo' command above:</p>
1209 </p>
1210
1211 <div class="doc_code">
1212 <pre>
1213 $ sudo update-binfmts --install llvm /path/to/lli --magic 'BC'
1214 </pre>
1215 </div>
1216
1217 </div>
1218
1219 <!-- *********************************************************************** -->
1220 <div class="doc_section">
1221   <a name="layout"><b>Program Layout</b></a>
1222 </div>
1223 <!-- *********************************************************************** -->
1224
1225 <div class="doc_text">
1226
1227 <p>One useful source of information about the LLVM source base is the LLVM <a
1228 href="http://www.doxygen.org">doxygen</a> documentation available at <tt><a
1229 href="http://llvm.org/doxygen/">http://llvm.org/doxygen/</a></tt>.
1230 The following is a brief introduction to code layout:</p>
1231
1232 </div>
1233
1234 <!-- ======================================================================= -->
1235 <div class="doc_subsection"><a name="examples"><tt>llvm/examples</tt></a></div>
1236 <div class="doc_text">
1237   <p>This directory contains some simple examples of how to use the LLVM IR and
1238   JIT.</p>
1239 </div>
1240
1241 <!-- ======================================================================= -->
1242 <div class="doc_subsection"><a name="include"><tt>llvm/include</tt></a></div>
1243 <div class="doc_text">
1244
1245 <p>This directory contains public header files exported from the LLVM
1246 library. The three main subdirectories of this directory are:</p>
1247
1248 <dl>
1249   <dt><tt><b>llvm/include/llvm</b></tt></dt>
1250   <dd>This directory contains all of the LLVM specific header files.  This
1251   directory also has subdirectories for different portions of LLVM:
1252   <tt>Analysis</tt>, <tt>CodeGen</tt>, <tt>Target</tt>, <tt>Transforms</tt>,
1253   etc...</dd>
1254
1255   <dt><tt><b>llvm/include/llvm/Support</b></tt></dt>
1256   <dd>This directory contains generic support libraries that are provided with
1257   LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities
1258   and a Command Line option processing library store their header files here.
1259   </dd>
1260
1261   <dt><tt><b>llvm/include/llvm/Config</b></tt></dt>
1262   <dd>This directory contains header files configured by the <tt>configure</tt>
1263   script.  They wrap "standard" UNIX and C header files.  Source code can
1264   include these header files which automatically take care of the conditional
1265   #includes that the <tt>configure</tt> script generates.</dd>
1266 </dl>
1267 </div>
1268
1269 <!-- ======================================================================= -->
1270 <div class="doc_subsection"><a name="lib"><tt>llvm/lib</tt></a></div>
1271 <div class="doc_text">
1272
1273 <p>This directory contains most of the source files of the LLVM system. In LLVM,
1274 almost all code exists in libraries, making it very easy to share code among the
1275 different <a href="#tools">tools</a>.</p>
1276
1277 <dl>
1278   <dt><tt><b>llvm/lib/VMCore/</b></tt></dt>
1279   <dd> This directory holds the core LLVM source files that implement core
1280   classes like Instruction and BasicBlock.</dd>
1281
1282   <dt><tt><b>llvm/lib/AsmParser/</b></tt></dt>
1283   <dd>This directory holds the source code for the LLVM assembly language parser
1284   library.</dd>
1285
1286   <dt><tt><b>llvm/lib/BitCode/</b></tt></dt>
1287   <dd>This directory holds code for reading and write LLVM bitcode.</dd>
1288
1289   <dt><tt><b>llvm/lib/Analysis/</b></tt><dd>This directory contains a variety of
1290   different program analyses, such as Dominator Information, Call Graphs,
1291   Induction Variables, Interval Identification, Natural Loop Identification,
1292   etc.</dd>
1293
1294   <dt><tt><b>llvm/lib/Transforms/</b></tt></dt>
1295   <dd> This directory contains the source code for the LLVM to LLVM program
1296   transformations, such as Aggressive Dead Code Elimination, Sparse Conditional
1297   Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global
1298   Elimination, and many others.</dd>
1299
1300   <dt><tt><b>llvm/lib/Target/</b></tt></dt>
1301   <dd> This directory contains files that describe various target architectures
1302   for code generation.  For example, the <tt>llvm/lib/Target/X86</tt>
1303   directory holds the X86 machine description while
1304   <tt>llvm/lib/Target/CBackend</tt> implements the LLVM-to-C converter.</dd>
1305
1306   <dt><tt><b>llvm/lib/CodeGen/</b></tt></dt>
1307   <dd> This directory contains the major parts of the code generator: Instruction
1308   Selector, Instruction Scheduling, and Register Allocation.</dd>
1309
1310   <dt><tt><b>llvm/lib/Debugger/</b></tt></dt>
1311   <dd> This directory contains the source level debugger library that makes
1312   it possible to instrument LLVM programs so that a debugger could identify
1313   source code locations at which the program is executing.</dd>
1314
1315   <dt><tt><b>llvm/lib/ExecutionEngine/</b></tt></dt>
1316   <dd> This directory contains libraries for executing LLVM bitcode directly
1317   at runtime in both interpreted and JIT compiled fashions.</dd>
1318
1319   <dt><tt><b>llvm/lib/Support/</b></tt></dt>
1320   <dd> This directory contains the source code that corresponds to the header
1321   files located in <tt>llvm/include/Support/</tt>.</dd>
1322
1323   <dt><tt><b>llvm/lib/System/</b></tt></dt>
1324   <dd>This directory contains the operating system abstraction layer that
1325   shields LLVM from platform-specific coding.</dd>
1326 </dl>
1327
1328 </div>
1329
1330 <!-- ======================================================================= -->
1331 <div class="doc_subsection"><a name="projects"><tt>llvm/projects</tt></a></div>
1332 <div class="doc_text">
1333   <p>This directory contains projects that are not strictly part of LLVM but are
1334   shipped with LLVM. This is also the directory where you should create your own
1335   LLVM-based projects. See <tt>llvm/projects/sample</tt> for an example of how
1336   to set up your own project.</p>
1337 </div>
1338
1339 <!-- ======================================================================= -->
1340 <div class="doc_subsection"><a name="runtime"><tt>llvm/runtime</tt></a></div>
1341 <div class="doc_text">
1342
1343 <p>This directory contains libraries which are compiled into LLVM bitcode and
1344 used when linking programs with the GCC front end.  Most of these libraries are
1345 skeleton versions of real libraries; for example, libc is a stripped down
1346 version of glibc.</p>
1347
1348 <p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
1349 end to compile.</p>
1350
1351 </div>
1352
1353 <!-- ======================================================================= -->
1354 <div class="doc_subsection"><a name="test"><tt>llvm/test</tt></a></div>
1355 <div class="doc_text">
1356   <p>This directory contains feature and regression tests and other basic sanity
1357   checks on the LLVM infrastructure. These are intended to run quickly and cover
1358   a lot of territory without being exhaustive.</p>
1359 </div>
1360
1361 <!-- ======================================================================= -->
1362 <div class="doc_subsection"><a name="test-suite"><tt>test-suite</tt></a></div>
1363 <div class="doc_text">
1364   <p>This is not a directory in the normal llvm module; it is a separate
1365   Subversion
1366   module that must be checked out (usually to <tt>projects/test-suite</tt>).
1367   This
1368   module contains a comprehensive correctness, performance, and benchmarking
1369   test
1370   suite for LLVM. It is a separate Subversion module because not every LLVM
1371   user is
1372   interested in downloading or building such a comprehensive test suite. For
1373   further details on this test suite, please see the
1374   <a href="TestingGuide.html">Testing Guide</a> document.</p>
1375 </div>
1376
1377 <!-- ======================================================================= -->
1378 <div class="doc_subsection"><a name="tools"><tt>llvm/tools</tt></a></div>
1379 <div class="doc_text">
1380
1381 <p>The <b>tools</b> directory contains the executables built out of the
1382 libraries above, which form the main part of the user interface.  You can
1383 always get help for a tool by typing <tt>tool_name -help</tt>.  The
1384 following is a brief introduction to the most important tools.  More detailed
1385 information is in the <a href="CommandGuide/index.html">Command Guide</a>.</p>
1386
1387 <dl>
1388
1389   <dt><tt><b>bugpoint</b></tt></dt>
1390   <dd><tt>bugpoint</tt> is used to debug
1391   optimization passes or code generation backends by narrowing down the
1392   given test case to the minimum number of passes and/or instructions that
1393   still cause a problem, whether it is a crash or miscompilation. See <a
1394   href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
1395   on using <tt>bugpoint</tt>.</dd>
1396
1397   <dt><tt><b>llvmc</b></tt></dt>
1398   <dd>The LLVM Compiler Driver. This program can
1399   be configured to utilize both LLVM and non-LLVM compilation tools to enable
1400   pre-processing, translation, optimization, assembly, and linking of programs
1401   all from one command line. <tt>llvmc</tt> also takes care of processing the
1402   dependent libraries found in bitcode. This reduces the need to get the
1403   traditional <tt>-l&lt;name&gt;</tt> options right on the command line. Please
1404   note that this tool, while functional, is still experimental and not feature
1405   complete.</dd>
1406
1407   <dt><tt><b>llvm-ar</b></tt></dt>
1408   <dd>The archiver produces an archive containing
1409   the given LLVM bitcode files, optionally with an index for faster
1410   lookup.</dd>
1411
1412   <dt><tt><b>llvm-as</b></tt></dt>
1413   <dd>The assembler transforms the human readable LLVM assembly to LLVM
1414   bitcode.</dd>
1415
1416   <dt><tt><b>llvm-dis</b></tt></dt>
1417   <dd>The disassembler transforms the LLVM bitcode to human readable
1418   LLVM assembly.</dd>
1419
1420   <dt><tt><b>llvm-ld</b></tt></dt>
1421   <dd><tt>llvm-ld</tt> is a general purpose and extensible linker for LLVM.
1422   This is the linker invoked by <tt>llvmc</tt>. It performs standard link time
1423   optimizations and allows optimization modules to be loaded and run so that
1424   language specific optimizations can be applied at link time.</dd>
1425
1426   <dt><tt><b>llvm-link</b></tt></dt>
1427   <dd><tt>llvm-link</tt>, not surprisingly, links multiple LLVM modules into
1428   a single program.</dd>
1429
1430   <dt><tt><b>lli</b></tt></dt>
1431   <dd><tt>lli</tt> is the LLVM interpreter, which
1432   can directly execute LLVM bitcode (although very slowly...). For architectures
1433   that support it (currently x86, Sparc, and PowerPC), by default, <tt>lli</tt>
1434   will function as a Just-In-Time compiler (if the functionality was compiled
1435   in), and will execute the code <i>much</i> faster than the interpreter.</dd>
1436
1437   <dt><tt><b>llc</b></tt></dt>
1438   <dd> <tt>llc</tt> is the LLVM backend compiler, which
1439   translates LLVM bitcode to a native code assembly file or to C code (with
1440   the -march=c option).</dd>
1441
1442   <dt><tt><b>llvm-gcc</b></tt></dt>
1443   <dd><tt>llvm-gcc</tt> is a GCC-based C frontend that has been retargeted to
1444   use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM
1445   bitcode or assembly (with the <tt>-emit-llvm</tt> option) instead of the
1446   usual machine code output.  It works just like any other GCC compiler,
1447   taking the typical <tt>-c, -S, -E, -o</tt> options that are typically used.
1448   Additionally, the the source code for <tt>llvm-gcc</tt> is available as a
1449   separate Subversion module.</dd>
1450
1451   <dt><tt><b>opt</b></tt></dt>
1452   <dd><tt>opt</tt> reads LLVM bitcode, applies a series of LLVM to LLVM
1453   transformations (which are specified on the command line), and then outputs
1454   the resultant bitcode.  The '<tt>opt -help</tt>' command is a good way to
1455   get a list of the program transformations available in LLVM.<br>
1456   <dd><tt>opt</tt> can also be used to run a specific analysis on an input
1457   LLVM bitcode file and print out the results.  It is primarily useful for
1458   debugging analyses, or familiarizing yourself with what an analysis does.</dd>
1459 </dl>
1460 </div>
1461
1462 <!-- ======================================================================= -->
1463 <div class="doc_subsection"><a name="utils"><tt>llvm/utils</tt></a></div>
1464 <div class="doc_text">
1465
1466 <p>This directory contains utilities for working with LLVM source code, and some
1467 of the utilities are actually required as part of the build process because they
1468 are code generators for parts of LLVM infrastructure.</p>
1469
1470 <dl>
1471   <dt><tt><b>codegen-diff</b></tt> <dd><tt>codegen-diff</tt> is a script
1472   that finds differences between code that LLC generates and code that LLI
1473   generates. This is a useful tool if you are debugging one of them,
1474   assuming that the other generates correct output. For the full user
1475   manual, run <tt>`perldoc codegen-diff'</tt>.<br><br>
1476
1477   <dt><tt><b>emacs/</b></tt> <dd>The <tt>emacs</tt> directory contains
1478   syntax-highlighting files which will work with Emacs and XEmacs editors,
1479   providing syntax highlighting support for LLVM assembly files and TableGen
1480   description files. For information on how to use the syntax files, consult
1481   the <tt>README</tt> file in that directory.<br><br>
1482
1483   <dt><tt><b>getsrcs.sh</b></tt> <dd>The <tt>getsrcs.sh</tt> script finds
1484   and outputs all non-generated source files, which is useful if one wishes
1485   to do a lot of development across directories and does not want to
1486   individually find each file. One way to use it is to run, for example:
1487   <tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
1488   tree.<br><br>
1489
1490   <dt><tt><b>llvmgrep</b></tt></dt>
1491   <dd>This little tool performs an "egrep -H -n" on each source file in LLVM and
1492   passes to it a regular expression provided on <tt>llvmgrep</tt>'s command
1493   line. This is a very efficient way of searching the source base for a
1494   particular regular expression.</dd>
1495
1496   <dt><tt><b>makellvm</b></tt> <dd>The <tt>makellvm</tt> script compiles all
1497   files in the current directory and then compiles and links the tool that
1498   is the first argument. For example, assuming you are in the directory
1499   <tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
1500   simply running <tt>makellvm llc</tt> will make a build of the current
1501   directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
1502   causing a re-linking of LLC.<br><br>
1503
1504   <dt><tt><b>NewNightlyTest.pl</b></tt> and
1505   <tt><b>NightlyTestTemplate.html</b></tt> <dd>These files are used in a
1506   cron script to generate nightly status reports of the functionality of
1507   tools, and the results can be seen by following the appropriate link on
1508   the <a href="http://llvm.org/">LLVM homepage</a>.<br><br>
1509
1510   <dt><tt><b>TableGen/</b></tt> <dd>The <tt>TableGen</tt> directory contains
1511   the tool used to generate register descriptions, instruction set
1512   descriptions, and even assemblers from common TableGen description
1513   files.<br><br>
1514
1515   <dt><tt><b>vim/</b></tt> <dd>The <tt>vim</tt> directory contains
1516   syntax-highlighting files which will work with the VIM editor, providing
1517   syntax highlighting support for LLVM assembly files and TableGen
1518   description files. For information on how to use the syntax files, consult
1519   the <tt>README</tt> file in that directory.<br><br>
1520
1521 </dl>
1522
1523 </div>
1524
1525 <!-- *********************************************************************** -->
1526 <div class="doc_section">
1527   <a name="tutorial">An Example Using the LLVM Tool Chain</a>
1528 </div>
1529 <!-- *********************************************************************** -->
1530
1531 <div class="doc_text">
1532 <p>This section gives an example of using LLVM.  llvm-gcc3 is now obsolete,
1533 so we only include instructions for llvm-gcc4.
1534 </p>
1535
1536 <p><b>Note:</b> The <i>gcc4</i> frontend's invocation is <b><i>considerably different</i></b>
1537 from the previous <i>gcc3</i> frontend. In particular, the <i>gcc4</i> frontend <b><i>does not</i></b>
1538 create bitcode by default: <i>gcc4</i> produces native code. As the example below illustrates,
1539 the '--emit-llvm' flag is needed to produce LLVM bitcode output. For <i>makefiles</i> and
1540 <i>configure</i> scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode
1541 output.</p>
1542 </div>
1543
1544 <!-- ======================================================================= -->
1545 <div class="doc_subsection"><a name="tutorial4">Example with llvm-gcc4</a></div>
1546
1547 <div class="doc_text">
1548
1549 <ol>
1550   <li><p>First, create a simple C file, name it 'hello.c':</p>
1551
1552 <div class="doc_code">
1553 <pre>
1554 #include &lt;stdio.h&gt;
1555
1556 int main() {
1557   printf("hello world\n");
1558   return 0;
1559 }
1560 </pre></div></li>
1561
1562   <li><p>Next, compile the C file into a native executable:</p>
1563
1564       <div class="doc_code"><pre>% llvm-gcc hello.c -o hello</pre></div>
1565
1566       <p>Note that llvm-gcc works just like GCC by default.  The standard -S and
1567         -c arguments work as usual (producing a native .s or .o file,
1568         respectively).</p></li>
1569
1570   <li><p>Next, compile the C file into a LLVM bitcode file:</p>
1571
1572       <div class="doc_code">
1573       <pre>% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc</pre></div>
1574
1575       <p>The -emit-llvm option can be used with the -S or -c options to emit an
1576          LLVM ".ll" or ".bc" file (respectively) for the code.  This allows you
1577          to use the <a href="CommandGuide/index.html">standard LLVM tools</a> on
1578          the bitcode file.</p>
1579
1580       <p>Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
1581          </p></li>
1582
1583   <li><p>Run the program in both forms. To run the program, use:</p>
1584
1585       <div class="doc_code"><pre>% ./hello</pre></div>
1586
1587       <p>and</p>
1588
1589       <div class="doc_code"><pre>% lli hello.bc</pre></div>
1590
1591       <p>The second examples shows how to invoke the LLVM JIT, <a
1592        href="CommandGuide/html/lli.html">lli</a>.</p></li>
1593
1594   <li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
1595       code:</p>
1596
1597 <div class="doc_code">
1598 <pre>llvm-dis &lt; hello.bc | less</pre>
1599 </div></li>
1600
1601   <li><p>Compile the program to native assembly using the LLC code
1602       generator:</p>
1603
1604       <div class="doc_code"><pre>% llc hello.bc -o hello.s</pre></div></li>
1605
1606   <li><p>Assemble the native assembly language file into a program:</p>
1607
1608 <div class="doc_code">
1609 <pre>
1610 <b>Solaris:</b> % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
1611
1612 <b>Others:</b>  % gcc hello.s -o hello.native
1613 </pre>
1614 </div></li>
1615
1616   <li><p>Execute the native code program:</p>
1617
1618       <div class="doc_code"><pre>% ./hello.native</pre></div>
1619
1620       <p>Note that using llvm-gcc to compile directly to native code (i.e. when
1621          the -emit-llvm option is not present) does steps 6/7/8 for you.</p>
1622         </li>
1623
1624 </ol>
1625
1626 </div>
1627
1628
1629 <!-- *********************************************************************** -->
1630 <div class="doc_section">
1631   <a name="problems">Common Problems</a>
1632 </div>
1633 <!-- *********************************************************************** -->
1634
1635 <div class="doc_text">
1636
1637 <p>If you are having problems building or using LLVM, or if you have any other
1638 general questions about LLVM, please consult the <a href="FAQ.html">Frequently
1639 Asked Questions</a> page.</p>
1640
1641 </div>
1642
1643 <!-- *********************************************************************** -->
1644 <div class="doc_section">
1645   <a name="links">Links</a>
1646 </div>
1647 <!-- *********************************************************************** -->
1648
1649 <div class="doc_text">
1650
1651 <p>This document is just an <b>introduction</b> on how to use LLVM to do
1652 some simple things... there are many more interesting and complicated things
1653 that you can do that aren't documented here (but we'll gladly accept a patch
1654 if you want to write something up!).  For more information about LLVM, check
1655 out:</p>
1656
1657 <ul>
1658   <li><a href="http://llvm.org/">LLVM homepage</a></li>
1659   <li><a href="http://llvm.org/doxygen/">LLVM doxygen tree</a></li>
1660   <li><a href="http://llvm.org/docs/Projects.html">Starting a Project
1661   that Uses LLVM</a></li>
1662 </ul>
1663
1664 </div>
1665
1666 <!-- *********************************************************************** -->
1667
1668 <hr>
1669 <address>
1670   <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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1673   src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
1674
1675   <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1676   <a href="http://llvm.x10sys.com/rspencer/">Reid Spencer</a><br>
1677   <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
1678   Last modified: $Date$
1679 </address>
1680 </body>
1681 </html>